View source for Medicine:Myocardial infarction

{{short description|Interruption of blood supply to a part of the heart}}
{{not to be confused|cardiac arrest|congestive heart failure}}
{{Infobox medical condition (new)
| name          = Myocardial infarction
| synonyms      = Acute myocardial infarction (AMI), heart attack
| image         = Blausen 0463 HeartAttack.png
| caption       = A myocardial infarction occurs when an [[Medicine:Atherosclerosis|atherosclerotic]] [[Medicine:Atheroma|plaque]] slowly builds up in the inner lining of a coronary artery and then suddenly ruptures, causing catastrophic [[Medicine:Thrombus|thrombus]] formation, totally occluding the artery and preventing blood flow downstream to the heart muscle.
| field         = [[Medicine:Cardiology|Cardiology]], [[Medicine:Emergency medicine|emergency medicine]]
| symptoms      = [[Medicine:Chest pain|Chest pain]], shortness of breath, nausea/vomiting, [[Medicine:Dizziness|dizziness]] or [[Medicine:Presyncope|lightheadedness]], cold sweat, feeling tired; arm, neck, back, jaw, or stomach pain,<ref name=HLB2014 /><ref>{{cite web|url=https://www.heart.org/en/health-topics/heart-attack/warning-signs-of-a-heart-attack/heart-attack-symptoms-in-women|title=Heart Attack Symptoms in Women|website=American Heart Association}}</ref> [[Medicine:Altered level of consciousness|decreased level]] or [[Medicine:Unconsciousness|total loss of consciousness]]
| complications = [[Medicine:Heart failure|Heart failure]], irregular heartbeat, [[Medicine:Cardiogenic shock|cardiogenic shock]], [[Medicine:Coma|coma]], [[Medicine:Cardiac arrest|cardiac arrest]]<ref name=HLB2013MI /><ref name=Heart2015 />
| onset         = 
| duration      = 
| causes        = Usually [[Medicine:Coronary artery disease|coronary artery disease]]<ref name=HLB2013MI />
| risks         = [[Medicine:Hypertension|High blood pressure]], [[Chemistry:Tobacco smoking|smoking]], [[Medicine:Diabetes mellitus|diabetes]], lack of exercise, obesity, high blood cholesterol<ref name=Meh2014 /><ref name=WHO2011 />
| diagnosis     = Electrocardiograms (ECGs), blood tests, coronary angiography<ref name=HLB2013D />
| differential  = 
| prevention    = 
| treatment     = [[Medicine:Percutaneous coronary intervention|Percutaneous coronary intervention]], thrombolysis<ref name=Europe2012 />
| medication    = [[Chemistry:Aspirin|Aspirin]], [[Chemistry:Nitroglycerin (drug)|nitroglycerin]], [[Chemistry:Heparin|heparin]]<ref name=Europe2012 /><ref name=Oc2010 />
| prognosis     = STEMI 10% risk of death (developed world)<ref name=Europe2012 />
| frequency     = 15.9 million (2015)<ref name=GBD2015Pre />
| deaths        = 
}}
<!-- Definition and symptoms -->
A '''myocardial infarction''' ('''MI'''), commonly known as a '''heart attack''', occurs when [[Medicine:Ischemia|blood flow decreases]] or stops in one of the [[Biology:Coronary arteries|coronary arteries]] of the [[Biology:Heart|heart]], causing infarction (tissue death) to the [[Biology:Cardiac muscle|heart muscle]].<ref name=HLB2014 /> The most common symptom is [[Medicine:Angina|chest pain or discomfort]] which may travel into the shoulder, arm, back, neck or jaw.<ref name=HLB2014 /> Often such pain occurs in the center or left side of the chest and lasts for more than a few minutes.<ref name=HLB2014 /> The discomfort may occasionally feel like heartburn.<ref name=HLB2014 /> Other symptoms may include shortness of breath, nausea, [[Medicine:Presyncope|feeling faint]], a cold sweat, [[Medicine:Fatigue|feeling tired]], and decreased level of consciousness.<ref name="HLB2014">{{cite web|title=What Are the Signs and Symptoms of Coronary Heart Disease?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/cad/signs|website=www.nhlbi.nih.gov|access-date=23 February 2015|date=September 29, 2014|url-status=dead|archive-url=https://web.archive.org/web/20150224034615/http://www.nhlbi.nih.gov/health/health-topics/topics/cad/signs|archive-date=24 February 2015}}</ref> About 30% of people have atypical symptoms.<ref name="Europe2012" /> Women more often present without chest pain and instead have neck pain, arm pain or feel tired.<ref>{{cite journal | vauthors = Coventry LL, Finn J, Bremner AP | title = Sex differences in symptom presentation in acute myocardial infarction: a systematic review and meta-analysis | journal = Heart & Lung | volume = 40 | issue = 6 | pages = 477–91 | date = 2011 | pmid = 22000678 | doi = 10.1016/j.hrtlng.2011.05.001 }}</ref> Among those over 75 years old, about 5% have had an MI with little or no history of symptoms.<ref name="Val2011">{{cite journal | vauthors = Valensi P, Lorgis L, Cottin Y | title = Prevalence, incidence, predictive factors and prognosis of silent myocardial infarction: a review of the literature | journal = Archives of Cardiovascular Diseases | volume = 104 | issue = 3 | pages = 178–88 | date = March 2011 | pmid = 21497307 | doi = 10.1016/j.acvd.2010.11.013 | doi-access = free }}</ref> An MI may cause [[Medicine:Heart failure|heart failure]], an irregular heartbeat, [[Medicine:Cardiogenic shock|cardiogenic shock]] or [[Medicine:Cardiac arrest|cardiac arrest]].<ref name=HLB2013MI /><ref name=Heart2015>{{cite web|title=Heart Attack or Sudden Cardiac Arrest: How Are They Different?|url=http://www.heart.org/HEARTORG/Conditions/More/MyHeartandStrokeNews/Heart-Attack-or-Sudden-Cardiac-Arrest-How-Are-They-Different_UCM_440804_Article.jsp|website=www.heart.org|access-date=24 February 2015|date=Jul 30, 2014|url-status=live|archive-url=https://web.archive.org/web/20150224045054/http://www.heart.org/HEARTORG/Conditions/More/MyHeartandStrokeNews/Heart-Attack-or-Sudden-Cardiac-Arrest-How-Are-They-Different_UCM_440804_Article.jsp|archive-date=24 February 2015}}</ref>

<!--Mechanism & Diagnosis  -->
Most MIs occur due to [[Medicine:Coronary artery disease|coronary artery disease]].<ref name=HLB2013MI>{{cite web|title=What Is a Heart Attack?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/|website=www.nhlbi.nih.gov|access-date=24 February 2015|date=December 17, 2013|url-status=live|archive-url=https://web.archive.org/web/20150219152830/http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/|archive-date=19 February 2015}}</ref> Risk factors include [[Medicine:Hypertension|high blood pressure]], [[Chemistry:Tobacco smoking|smoking]], [[Medicine:Diabetes mellitus|diabetes]], lack of exercise, obesity, high blood cholesterol, poor diet, and excessive alcohol intake.<ref name=Meh2014>{{cite journal | vauthors = Mehta PK, Wei J, Wenger NK | title = Ischemic heart disease in women: a focus on risk factors | journal = Trends in Cardiovascular Medicine | volume = 25 | issue = 2 | pages = 140–51 | date = February 2015 | pmid = 25453985 | pmc = 4336825 | doi = 10.1016/j.tcm.2014.10.005 }}</ref><ref name=WHO2011>{{cite book | vauthors = Mendis S, Puska P, Norrving B |title=Global atlas on cardiovascular disease prevention and control |date=2011 |publisher=World Health Organization in collaboration with the World Heart Federation and the World Stroke Organization |location=Geneva |isbn=978-92-4-156437-3 |pages=3–18 |edition=1st |url=http://whqlibdoc.who.int/publications/2011/9789241564373_eng.pdf?ua=1 |url-status=live|archive-url= https://web.archive.org/web/20140817123106/http://whqlibdoc.who.int/publications/2011/9789241564373_eng.pdf?ua=1 |archive-date=2014-08-17 }}</ref> The complete blockage of a coronary artery caused by a rupture of an [[Medicine:Atherosclerosis|atherosclerotic plaque]] is usually the underlying mechanism of an MI.<ref name=HLB2013MI /> MIs are less commonly caused by coronary artery spasms, which may be due to [[Biology:Cocaine|cocaine]], significant emotional stress (often known as Takotsubo syndrome or ''broken heart syndrome'') and extreme cold, among others.<ref>{{cite web|title=What Causes a Heart Attack?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/causes|website=www.nhlbi.nih.gov|access-date=24 February 2015|date=December 17, 2013|url-status=live|archive-url=https://web.archive.org/web/20150218075735/http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/causes|archive-date=18 February 2015}}</ref><ref>{{cite journal | vauthors = Devlin RJ, Henry JA | title = Clinical review: Major consequences of illicit drug consumption | journal = Critical Care | volume = 12 | issue = 1 | pages = 202 | date = 2008 | pmid = 18279535 | pmc = 2374627 | doi = 10.1186/cc6166 | doi-access = free }}</ref> Many tests are helpful to help with diagnosis, including electrocardiograms (ECGs), blood tests and coronary angiography.<ref name=HLB2013D>{{cite web|title=How Is a Heart Attack Diagnosed?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/diagnosis|website=www.nhlbi.nih.gov|access-date=24 February 2015|date=December 17, 2013|url-status=live|archive-url= https://web.archive.org/web/20150224044949/http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/diagnosis |archive-date=24 February 2015 }}</ref> An ECG, which is a recording of the heart's electrical activity, may confirm an '''ST elevation MI''' (STEMI), if [[Medicine:ST elevation|ST elevation]] is present.<ref name=Europe2012 /><ref>{{cite web|title=Electrocardiogram | work = NHLBI, NIH |url= https://www.nhlbi.nih.gov/health/health-topics/topics/ekg |access-date=10 April 2017|date=9 December 2016|url-status=live |archive-url= https://web.archive.org/web/20170411140634/https://www.nhlbi.nih.gov/health/health-topics/topics/ekg |archive-date=11 April 2017}}</ref> Commonly used blood tests include [[Biology:Troponin|troponin]] and less often [[Medicine:CPK-MB test|creatine kinase MB]].<ref name=HLB2013D />

<!-- Management -->
Treatment of an MI is time-critical.<ref name=Davidsons2010>{{cite book | vauthors = Colledge NR, Walker BR, Ralston SH, Davidson LS |title=Davidson's principles and practice of medicine |date=2010 |publisher=Churchill Livingstone/Elsevier |location=Edinburgh |isbn=978-0-7020-3085-7 |edition=21st |pages=588–599}}</ref> [[Chemistry:Aspirin|Aspirin]] is an appropriate immediate treatment for a suspected MI.<ref name=Oc2010 /> [[Chemistry:Nitroglycerin (drug)|Nitroglycerin]] or [[Chemistry:Opioid|opioid]]s may be used to help with chest pain; however, they do not improve overall outcomes.<ref name=Europe2012 /><ref name=Oc2010 /> [[Chemistry:Oxygen therapy|Supplemental oxygen]] is recommended in those with [[Medicine:Hypoxia (medical)|low oxygen levels]] or shortness of breath.<ref name=Oc2010>{{cite journal | vauthors = O'Connor RE, Brady W, Brooks SC, Diercks D, Egan J, Ghaemmaghami C, Menon V, O'Neil BJ, Travers AH, Yannopoulos D | display-authors = 6 | title = Part 10: acute coronary syndromes: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 122 | issue = 18 Suppl 3 | pages = S787–817 | date = November 2010 | pmid = 20956226 | doi = 10.1161/CIRCULATIONAHA.110.971028 | doi-access = free }}</ref> In a STEMI, treatments attempt to restore blood flow to the heart and include [[Medicine:Percutaneous coronary intervention|percutaneous coronary intervention]] (PCI), where the arteries are pushed open and may be [[Medicine:Stent|stent]]ed, or thrombolysis, where the blockage is removed using medications.<ref name=Europe2012 /> People who have a '''non-ST elevation myocardial infarction''' (NSTEMI) are often managed with the blood thinner [[Chemistry:Heparin|heparin]], with the additional use of PCI in those at high risk.<ref name=Oc2010 /> In people with blockages of multiple coronary arteries and diabetes, [[Medicine:Coronary artery bypass surgery|coronary artery bypass surgery]] (CABG) may be recommended rather than [[Medicine:Angioplasty|angioplasty]].<ref name=Hamm2011>{{cite journal | vauthors = Hamm CW, Bassand JP, Agewall S, Bax J, Boersma E, Bueno H, Caso P, Dudek D, Gielen S, Huber K, Ohman M, Petrie MC, Sonntag F, Uva MS, Storey RF, Wijns W, Zahger D | display-authors = 6 | title = ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation: The Task Force for the management of acute coronary syndromes (ACS) in patients presenting without persistent ST-segment elevation of the European Society of Cardiology (ESC) | journal = European Heart Journal | volume = 32 | issue = 23 | pages = 2999–3054 | date = December 2011 | pmid = 21873419 | doi = 10.1093/eurheartj/ehr236 | doi-access = free }}</ref> After an MI, lifestyle modifications, along with long-term treatment with aspirin, beta blockers and [[Biology:Statin|statin]]s, are typically recommended.<ref name=Europe2012 />

<!-- Epidemiology and culture-->
Worldwide, about 15.9 million myocardial infarctions occurred in 2015.<ref name=GBD2015Pre>{{cite journal | vauthors = Vos T, Allen C, Arora M, Barber RM, Bhutta ZA, Brown A, etal  | collaboration = GBD 2015 Disease Injury Incidence Prevalence Collaborators | title = Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015 | journal = Lancet | volume = 388 | issue = 10053 | pages = 1545–1602 | date = October 2016 | pmid = 27733282 | pmc = 5055577 | doi = 10.1016/S0140-6736(16)31678-6 }}</ref> More than 3 million people had an ST elevation MI, and more than 4 million had an NSTEMI.<ref name=Lancet08>{{cite journal | vauthors = White HD, Chew DP | title = Acute myocardial infarction | journal = Lancet | volume = 372 | issue = 9638 | pages = 570–84 | date = August 2008 | pmid = 18707987 | pmc = 1931354 | doi = 10.1016/S0140-6736(08)61237-4 }}</ref> STEMIs occur about twice as often in men as women.<ref name=AHA2013>{{cite journal | vauthors = O'Gara PT, Kushner FG, Ascheim DD, Casey DE, Chung MK, de Lemos JA, Ettinger SM, Fang JC, Fesmire FM, Franklin BA, Granger CB, Krumholz HM, Linderbaum JA, Morrow DA, Newby LK, Ornato JP, Ou N, Radford MJ, Tamis-Holland JE, Tommaso CL, Tracy CM, Woo YJ, Zhao DX, Anderson JL, Jacobs AK, Halperin JL, Albert NM, Brindis RG, Creager MA, DeMets D, Guyton RA, Hochman JS, Kovacs RJ, Kushner FG, Ohman EM, Stevenson WG, Yancy CW | display-authors = 6 | title = 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines | journal = Circulation | volume = 127 | issue = 4 | pages = e362–425 | date = January 2013 | pmid = 23247304 | doi = 10.1161/CIR.0b013e3182742cf6 | doi-access = free }}</ref> About one million people have an MI each year in the United States.<ref name=HLB2013MI /> In the developed world, the risk of death in those who have had a STEMI is about 10%.<ref name=Europe2012>{{cite journal | vauthors = Steg PG, James SK, Atar D, Badano LP, Blömstrom-Lundqvist C, Borger MA, Di Mario C, Dickstein K, Ducrocq G, Fernandez-Aviles F, Gershlick AH, Giannuzzi P, Halvorsen S, Huber K, Juni P, Kastrati A, Knuuti J, Lenzen MJ, Mahaffey KW, Valgimigli M, van 't Hof A, Widimsky P, Zahger D | display-authors = 6 | title = ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation | journal = European Heart Journal | volume = 33 | issue = 20 | pages = 2569–619 | date = October 2012 | pmid = 22922416 | doi = 10.1093/eurheartj/ehs215 | doi-access = free }}</ref> Rates of MI for a given age have decreased globally between 1990 and 2010.<ref>{{cite journal | vauthors = Moran AE, Forouzanfar MH, Roth GA, Mensah GA, Ezzati M, Flaxman A, Murray CJ, Naghavi M | display-authors = 6 | title = The global burden of ischemic heart disease in 1990 and 2010: the Global Burden of Disease 2010 study | journal = Circulation | volume = 129 | issue = 14 | pages = 1493–501 | date = April 2014 | pmid = 24573351 | pmc = 4181601 | doi = 10.1161/circulationaha.113.004046 }}</ref> In 2011, an MI was one of the top five most expensive conditions during inpatient hospitalizations in the US, with a cost of about $11.5 billion for 612,000 hospital stays.<ref>{{cite web| vauthors = Torio C |title=National Inpatient Hospital Costs: The Most Expensive Conditions by Payer, 2011|url=http://hcup-us.ahrq.gov/reports/statbriefs/sb160.jsp|website=HCUP|access-date=1 May 2017|date=August 2013|url-status=live|archive-url=https://web.archive.org/web/20170314171958/https://www.hcup-us.ahrq.gov/reports/statbriefs/sb160.jsp|archive-date=14 March 2017}}</ref>

== Terminology ==
{{Main|Medicine:Acute coronary syndrome}}
Myocardial infarction (MI) refers to tissue death (infarction) of the heart muscle (myocardium) caused by ischemia, the lack of oxygen delivery to myocardial tissue. It is a type of [[Medicine:Acute coronary syndrome|acute coronary syndrome]], which describes a sudden or short-term change in symptoms related to blood flow to the heart.{{sfnm|1a1=Morrow|1a2=Braunwald|1y=2016|1pp=1-3|2a1=Dwight|2y=2016|2p=41}} Unlike the other type of acute coronary syndrome, unstable angina, a myocardial infarction occurs when there is cell death, which can be estimated by measuring by a [[Medicine:Blood test|blood test]] for [[Medicine:Biomarker|biomarkers]] (the cardiac protein [[Biology:Troponin|troponin]]).{{sfn|Morrow|Braunwald|2016|pp=1-3}} When there is evidence of an MI, it may be classified as an ST elevation myocardial infarction (STEMI) or Non-ST elevation myocardial infarction (NSTEMI) based on the results of an ECG.<ref name=THIRDDEF />

The phrase "heart attack" is often used non-specifically to refer to myocardial infarction. An MI is different from—but can cause—[[Medicine:Cardiac arrest|cardiac arrest]], where the heart is not contracting at all or so poorly that all vital organs cease to function, thus leading to death.{{sfn|Blumenthal|Margolis|2007|pp=4-5}} It is also distinct from [[Medicine:Heart failure|heart failure]], in which the pumping action of the heart is impaired. However, an MI may lead to heart failure.{{sfn|Morrow|Bohula|2016|p=295}}

== Signs and symptoms ==
{{multiple image
 | direction = vertical
 | width = 250
 | image1 = AMI pain front.png
 | alt1 = View of the chest with common areas of MI coloured
 | image2 = AMI pain back.png
 | alt2 = View of the back with common areas of MI coloured
 | caption2 = Areas where pain is experienced in myocardial infarction, showing common (dark red) and less common (light red) areas on the chest (top) and back (bottom).
}}

Chest pain that may or may not radiate to other parts of the body is the most typical and significant symptom of myocardial infarction. It might be accompanied by other symptoms such as sweating.{{sfn|Morrow|2016|pp=59-61}}

=== Pain ===
[[Medicine:Chest pain|Chest pain]] is one of the most common symptoms of acute myocardial infarction and is often described as a sensation of tightness, pressure, or squeezing. Pain radiates most often to the left arm, but may also radiate to the lower jaw, neck, right arm, back, and upper [[Biology:Abdomen|abdomen]].<ref name=Harrisons2015>{{Cite book|title=Harrison's principles of internal medicine | vauthors = Kasper DL, Fauci AS, Hauser SL, Longo DL, Jameson JL, Loscalzo J |publisher=McGraw Hill Education|year=2015|isbn=978-0-07-180215-4|pages=1593–1610|oclc=923181481}}</ref>{{sfn|Morrow|2016|pp=59-60}} The pain most suggestive of an acute MI, with the highest [[Likelihood function|likelihood ratio]], is pain radiating to the right arm and shoulder.<ref name=Harrisons2015B>{{Cite book|title=Harrison's Principles of Internal Medicine  | vauthors = Kasper DL, Fauci AS, Hauser SL, Longo DL, Jameson JL, Loscalzo J |publisher=McGraw Hill Education|year=2015|isbn=978-0-07-180215-4|pages=98–99|oclc=923181481}}</ref>{{sfn|Morrow|2016|pp=59-60}} Similarly, chest pain similar to a previous heart attack is also suggestive.<ref name="Gupta2016">{{cite journal | vauthors = Gupta R, Munoz R | title = Evaluation and Management of Chest Pain in the Elderly | journal = Emergency Medicine Clinics of North America | volume = 34 | issue = 3 | pages = 523–42 | date = August 2016 | pmid = 27475013 | doi = 10.1016/j.emc.2016.04.006 }}</ref> The pain associated with MI is usually diffuse, does not change with position, and lasts for more than 20 minutes.<ref name="THIRDDEF">{{cite journal | vauthors = Thygesen K, Alpert JS, Jaffe AS, Simoons ML, Chaitman BR, White HD, Katus HA, Lindahl B, Morrow DA, Clemmensen PM, Johanson P, Hod H, Underwood R, Bax JJ, Bonow RO, Pinto F, Gibbons RJ, Fox KA, Atar D, Newby LK, Galvani M, Hamm CW, Uretsky BF, Steg PG, Wijns W, Bassand JP, Menasché P, Ravkilde J, Ohman EM, Antman EM, Wallentin LC, Armstrong PW, Simoons ML, Januzzi JL, Nieminen MS, Gheorghiade M, Filippatos G, Luepker RV, Fortmann SP, Rosamond WD, Levy D, Wood D, Smith SC, Hu D, Lopez-Sendon JL, Robertson RM, Weaver D, Tendera M, Bove AA, Parkhomenko AN, Vasilieva EJ, Mendis S | display-authors = 6 | title = Third universal definition of myocardial infarction | journal = Circulation | volume = 126 | issue = 16 | pages = 2020–35 | date = October 2012 | pmid = 22923432 | doi = 10.1161/CIR.0b013e31826e1058 | doi-access = free }}</ref> It might be described as pressure, tightness, knifelike, tearing, burning sensation (all these are also manifested during other diseases). It could be felt as an unexplained anxiety, and pain might be absent altogether.{{sfn|Morrow|2016|pp=59-60}} Levine's sign, in which a person localizes the chest pain by clenching one or both fists over their sternum, has classically been thought to be predictive of cardiac chest pain, although a prospective observational study showed it had a poor positive predictive value.<ref name="pmid17208083">{{cite journal | vauthors = Marcus GM, Cohen J, Varosy PD, Vessey J, Rose E, Massie BM, Chatterjee K, Waters D | display-authors = 6 | title = The utility of gestures in patients with chest discomfort | journal = The American Journal of Medicine | volume = 120 | issue = 1 | pages = 83–9 | date = January 2007 | pmid = 17208083 | doi = 10.1016/j.amjmed.2006.05.045 }}</ref>

Typically, chest pain because of ischemia, be it unstable angina or myocardial infarction, lessens with the use of [[Chemistry:Nitroglycerin (drug)|nitroglycerin]], but nitroglycerin may also relieve chest pain arising from non-cardiac causes.{{sfnm|1a1=Allison|1a2=Murphy|1y=2012|1p=197|2a1=Morrow|2y=2016|2p=60}}

=== Other ===
Chest pain may be accompanied by sweating, nausea or vomiting, and [[Medicine:Syncope|fainting]],<ref name=THIRDDEF /><ref name=Harrisons2015B /> and these symptoms may also occur without any pain at all.<ref name=Harrisons2015 /> Dizziness or lightheadedness is common and occurs due to reduction in oxygen and blood to the brain. In women, the most common symptoms of myocardial infarction include shortness of breath, weakness, and fatigue.<ref name="ACSwomen">{{cite journal | vauthors = Canto JG, Goldberg RJ, Hand MM, Bonow RO, Sopko G, Pepine CJ, Long T | title = Symptom presentation of women with acute coronary syndromes: myth vs reality | journal = Archives of Internal Medicine | volume = 167 | issue = 22 | pages = 2405–2413 | date = December 2007 | pmid = 18071161 | doi = 10.1001/archinte.167.22.2405 | doi-access =  }}</ref> Women are more likely to have unusual or unexplained tiredness and nausea or vomiting as symptoms.<ref>{{cite web |title=Heart Attack Symptoms, Risk, and Recovery |url=https://www.cdc.gov/heartdisease/heart_attack.htm |website=CDC.gov |publisher=U.S. Department of Health & Human Services |access-date=July 20, 2021}}</ref> Women having heart attacks are more likely to have palpitations, back pain, labored breath, vomiting, and left arm pain than men, although the studies showing these differences had high variability.<ref>{{cite journal | vauthors = Coventry LL, Finn J, Bremner AP | title = Sex differences in symptom presentation in acute myocardial infarction: a systematic review and meta-analysis | journal = Heart & Lung | volume = 40 | issue = 6 | pages = 477–491 | date = November–December 2011 | pmid = 22000678 | doi = 10.1016/j.hrtlng.2011.05.001 }}</ref> Women are less likely to report chest pain during a heart attack and more likely to report nausea, jaw pain, neck pain, cough, and fatigue, although these findings are inconsistent across studies.<ref>{{cite journal | vauthors = Chen W, Woods SL, Puntillo KA | title = Gender differences in symptoms associated with acute myocardial infarction: a review of the research | journal = Heart & Lung | volume = 34 | issue = 4 | pages = 240–247 | date = July–August 2005 | pmid = 16027643 | doi = 10.1016/j.hrtlng.2004.12.004 }}</ref> Women with heart attacks also had more indigestion, dizziness, loss of appetite, and loss of consciousness.<ref>{{cite journal | vauthors = DeVon HA, Zerwic JJ | title = Symptoms of acute coronary syndromes: are there gender differences? A review of the literature | journal = Heart & Lung | volume = 31 | issue = 4 | pages = 235–245 | date = July–August 2002 | pmid = 12122387 | doi = 10.1067/mhl.2002.126105 }}</ref> Shortness of breath is a common, and sometimes the only symptom, occurring when damage to the heart limits the [[Medicine:Cardiac output|output]] of the left ventricle, with breathlessness arising either from [[Medicine:Hypoxemia|low oxygen in the blood]], or [[Medicine:Pulmonary edema|pulmonary edema]].<ref name=Harrisons2015 /><ref>{{cite web| vauthors = Ashton R, Raman D | title = Dyspnea |url= http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/pulmonary/dyspnea/ |website=www.clevelandclinicmeded.com|publisher=Cleveland Clinic |access-date=24 May 2017 |url-status=live |archive-url=https://web.archive.org/web/20170711084207/http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/pulmonary/dyspnea/|archive-date=11 July 2017}}</ref> Other less common symptoms include weakness, light-headedness, palpitations, and abnormalities in [[Heart rate|heart rate]] or [[Physics:Blood pressure|blood pressure]].<ref name=Davidsons2010 /> These symptoms are likely induced by a massive surge of catecholamines from the sympathetic nervous system, which occurs in response to pain and, where present, low [[Physics:Blood pressure|blood pressure]].<ref>{{cite book| vauthors = Lilly LS |title=Pathophysiology of Heart Disease: A Collaborative Project of Medical Students and Faculty|date=2012|publisher=Lippincott Williams & Wilkins |isbn=978-1-4698-1668-5 |page=172 |url= https://books.google.com/books?id=0lxSGJYeXikC&pg=PA172 |url-status=live |archive-url= https://web.archive.org/web/20170728135942/https://books.google.com.au/books?id=0lxSGJYeXikC&pg=PA172&lpg=PA172 |archive-date=2017-07-28 }}</ref> [[Medicine:Unconsciousness|Loss of consciousness]] can occur in myocardial infarctions due to inadequate blood flow to the [[Biology:Brain|brain]] and [[Medicine:Cardiogenic shock|cardiogenic shock]], and sudden death, frequently due to the development of [[Medicine:Ventricular fibrillation|ventricular fibrillation]]. <ref name='ESC STEMI'>{{cite journal | vauthors = Van de Werf F, Bax J, Betriu A, Blomstrom-Lundqvist C, Crea F, Falk V, Filippatos G, Fox K, Huber K, Kastrati A, Rosengren A, Steg PG, Tubaro M, Verheugt F, Weidinger F, Weis M | display-authors = 6 | title = Management of acute myocardial infarction in patients presenting with persistent ST-segment elevation: the Task Force on the Management of ST-Segment Elevation Acute Myocardial Infarction of the European Society of Cardiology | journal = European Heart Journal | volume = 29 | issue = 23 | pages = 2909–2945 | date = December 2008 | pmid = 19004841 | doi = 10.1093/eurheartj/ehn416 | doi-access = free }}</ref> When the brain was without oxygen for too long due to a myocardial infarction, [[Medicine:Coma|coma]] can occur. Cardiac arrest, and atypical symptoms such as [[Medicine:Palpitations|palpitations]], occur more frequently in women, the elderly, those with diabetes, in people who have just had surgery, and in critically ill patients.<ref name=THIRDDEF />

=== Absence ===
<!--Silent-->
"Silent" myocardial infarctions can happen without any symptoms at all.<ref name = Val2011 /> These cases can be discovered later on electrocardiograms, using blood enzyme tests, or at [[Medicine:Autopsy|autopsy]] after a person has died. Such silent myocardial infarctions represent between 22 and 64% of all infarctions,<ref name = Val2011 /> and are more common in the elderly,<ref name = Val2011 /> in those with [[Medicine:Diabetes mellitus|diabetes mellitus]]<ref name=Davidsons2010 /> and after [[Medicine:Heart transplantation|heart transplantation]]. In people with diabetes, differences in pain threshold, [[Medicine:Autonomic neuropathy|autonomic neuropathy]], and [[Social:Psychology|psychological]] factors have been cited as possible explanations for the lack of symptoms.<ref name="Diabetologica2004-David">{{cite journal | vauthors = Davis TM, Fortun P, Mulder J, Davis WA, Bruce DG | title = Silent myocardial infarction and its prognosis in a community-based cohort of Type 2 diabetic patients: the Fremantle Diabetes Study | journal = Diabetologia | volume = 47 | issue = 3 | pages = 395–399 | date = March 2004 | pmid = 14963648 | doi = 10.1007/s00125-004-1344-4 | s2cid = 12567614 }}</ref> In heart transplantation, the [[Medicine:Organ donation|donor]] heart is not fully innervated by the nervous system of the recipient.<ref name=rubin>{{cite book | vauthors = Rubin E, Gorstein F, Rubin R, Schwarting R, Strayer D | title = Rubin's Pathology&nbsp;— Clinicopathological Foundations of Medicine | publisher = Lippincott Williams & Wilkins | year = 2001 | location = Maryland | page = 549 | isbn = 978-0-7817-4733-2 }}</ref>

== Risk factors ==
The most prominent risk factors for myocardial infarction are older age, actively [[Medicine:Smoking|smoking]], [[Medicine:Hypertension|high blood pressure]], [[Medicine:Diabetes mellitus|diabetes mellitus]], and total [[Chemistry:Cholesterol|cholesterol]] and [[Medicine:High-density lipoprotein|high-density lipoprotein]] levels.{{sfn|Gaziano|Gaziano|2016|p=11-22}} Many risk factors of myocardial infarction are shared with [[Medicine:Coronary artery disease|coronary artery disease]], the primary cause of myocardial infarction,<ref name=Davidsons2010 /> with other risk factors including male sex, low levels of physical activity, a past [[Medicine:Family history|family history]], obesity, and alcohol use.<ref name=Davidsons2010 /> Risk factors for myocardial disease are often included in risk factor stratification scores, such as the [[Medicine:Framingham Risk Score|Framingham Risk Score]].<ref name=AHA2013 /> At any given age, men are more at risk than women for the development of cardiovascular disease.<ref name="EUROPEAN2012">{{cite journal | vauthors = Perk J, De Backer G, Gohlke H, Graham I, Reiner Z, Verschuren M, Albus C, Benlian P, Boysen G, Cifkova R, Deaton C, Ebrahim S, Fisher M, Germano G, Hobbs R, Hoes A, Karadeniz S, Mezzani A, Prescott E, Ryden L, Scherer M, Syvänne M, Scholte op Reimer WJ, Vrints C, Wood D, Zamorano JL, Zannad F | display-authors = 6 | title = European Guidelines on cardiovascular disease prevention in clinical practice (version 2012). The Fifth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (constituted by representatives of nine societies and by invited experts) | journal = European Heart Journal | volume = 33 | issue = 13 | pages = 1635–701 | date = July 2012 | pmid = 22555213 | doi = 10.1093/eurheartj/ehs092 | doi-access = free }}</ref> High levels of blood cholesterol is a known risk factor, particularly high [[Medicine:Low-density lipoprotein|low-density lipoprotein]], low [[Medicine:High-density lipoprotein|high-density lipoprotein]], and high triglycerides.<ref name="pmid=16697342">{{cite journal | vauthors = Smith SC, Allen J, Blair SN, Bonow RO, Brass LM, Fonarow GC, Grundy SM, Hiratzka L, Jones D, Krumholz HM, Mosca L, Pearson T, Pfeffer MA, Taubert KA | display-authors = 6 | title = AHA/ACC guidelines for secondary prevention for patients with coronary and other atherosclerotic vascular disease: 2006 update endorsed by the National Heart, Lung, and Blood Institute | journal = Journal of the American College of Cardiology | volume = 47 | issue = 10 | pages = 2130–9 | date = May 2006 | pmid = 16697342 | doi = 10.1016/j.jacc.2006.04.026 | doi-access = free }}</ref>

Many risk factors for myocardial infarction are potentially modifiable, with the most important being [[Chemistry:Tobacco smoking|tobacco smoking]] (including secondhand smoke).<ref name=Davidsons2010 /> Smoking appears to be the cause of about 36% and obesity the cause of 20% of [[Medicine:Coronary artery disease|coronary artery disease]].<ref name=Kivi2012 /> Lack of physical activity has been linked to 7–12% of cases.<ref name=Kivi2012 /><ref>{{cite journal | vauthors = Lee IM, Shiroma EJ, Lobelo F, Puska P, Blair SN, Katzmarzyk PT | title = Effect of physical inactivity on major non-communicable diseases worldwide: an analysis of burden of disease and life expectancy | journal = Lancet | volume = 380 | issue = 9838 | pages = 219–29 | date = July 2012 | pmid = 22818936 | pmc = 3645500 | doi = 10.1016/S0140-6736(12)61031-9 }}</ref> Less common causes include stress-related causes such as job stress, which accounts for about 3% of cases,<ref name=Kivi2012>{{cite journal | vauthors = Kivimäki M, Nyberg ST, Batty GD, Fransson EI, Heikkilä K, Alfredsson L, Bjorner JB, Borritz M, Burr H, Casini A, Clays E, De Bacquer D, Dragano N, Ferrie JE, Geuskens GA, Goldberg M, Hamer M, Hooftman WE, Houtman IL, Joensuu M, Jokela M, Kittel F, Knutsson A, Koskenvuo M, Koskinen A, Kouvonen A, Kumari M, Madsen IE, Marmot MG, Nielsen ML, Nordin M, Oksanen T, Pentti J, Rugulies R, Salo P, Siegrist J, Singh-Manoux A, Suominen SB, Väänänen A, Vahtera J, Virtanen M, Westerholm PJ, Westerlund H, Zins M, Steptoe A, Theorell T | display-authors = 6 | title = Job strain as a risk factor for coronary heart disease: a collaborative meta-analysis of individual participant data | journal = Lancet | volume = 380 | issue = 9852 | pages = 1491–7 | date = October 2012 | pmid = 22981903 | pmc = 3486012 | doi = 10.1016/S0140-6736(12)60994-5 }}</ref> and chronic high stress levels.<ref name="pmid=22473079">{{cite journal | vauthors = Steptoe A, Kivimäki M | title = Stress and cardiovascular disease | journal = Nature Reviews. Cardiology | volume = 9 | issue = 6 | pages = 360–70 | date = April 2012 | pmid = 22473079 | doi = 10.1038/nrcardio.2012.45 | s2cid = 27925226 }}</ref>

=== Diet ===
There is varying evidence about the importance of [[Chemistry:Saturated fat|saturated fat]] in the development of myocardial infarctions. Eating polyunsaturated fat instead of [[Chemistry:Saturated fat|saturated fat]]s has been shown in studies to be associated with a decreased risk of myocardial infarction,<ref name=":1">{{cite journal | vauthors = Hooper L, Martin N, Jimoh OF, Kirk C, Foster E, Abdelhamid AS | title = Reduction in saturated fat intake for cardiovascular disease | journal = The Cochrane Database of Systematic Reviews | volume = 2020 | pages = CD011737 | date = August 2020 | issue = 8 | pmid = 32827219 | doi = 10.1002/14651858.CD011737.pub3 | pmc = 8092457 }}</ref> while other studies find little evidence that reducing dietary saturated fat or increasing [[Chemistry:Polyunsaturated fat|polyunsaturated fat]] intake affects heart attack risk.<ref name=Chow2014>{{cite journal | vauthors = Chowdhury R, Warnakula S, Kunutsor S, Crowe F, Ward HA, Johnson L, Franco OH, Butterworth AS, Forouhi NG, Thompson SG, Khaw KT, Mozaffarian D, Danesh J, Di Angelantonio E | display-authors = 6 | title = Association of dietary, circulating, and supplement fatty acids with coronary risk: a systematic review and meta-analysis | journal = Annals of Internal Medicine | volume = 160 | issue = 6 | pages = 398–406 | date = March 2014 | pmid = 24723079 | doi = 10.7326/M13-1788 }}</ref><ref>{{cite journal | vauthors = de Souza RJ, Mente A, Maroleanu A, Cozma AI, Ha V, Kishibe T, Uleryk E, Budylowski P, Schünemann H, Beyene J, Anand SS | display-authors = 6 | title = Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies | journal = BMJ | volume = 351 | pages = h3978 | date = August 2015 | pmid = 26268692 | pmc = 4532752 | doi = 10.1136/bmj.h3978 }}</ref> Dietary cholesterol does not appear to have a significant effect on blood cholesterol and thus recommendations about its consumption may not be needed.<ref>{{cite web|title=Scientific Report of the 2015 Dietary Guidelines Advisory Committee|url=http://health.gov/dietaryguidelines/2015-scientific-report/PDFs/Scientific-Report-of-the-2015-Dietary-Guidelines-Advisory-Committee.pdf|website=health.gov|page=17|date=Feb 2015|url-status=dead|archive-url=https://web.archive.org/web/20160503071439/http://health.gov/dietaryguidelines/2015-scientific-report/PDFs/Scientific-Report-of-the-2015-Dietary-Guidelines-Advisory-Committee.pdf|archive-date=2016-05-03|access-date=2015-03-05}}</ref> Trans fats do appear to increase risk.<ref name=Chow2014 /> Acute and prolonged intake of high quantities of alcoholic drinks (3–4 or more daily) increases the risk of a heart attack.<ref name=Krenz2012>{{cite journal | vauthors = Krenz M, Korthuis RJ | title = Moderate ethanol ingestion and cardiovascular protection: from epidemiologic associations to cellular mechanisms | journal = Journal of Molecular and Cellular Cardiology | volume = 52 | issue = 1 | pages = 93–104 | date = January 2012 | pmid = 22041278 | pmc = 3246046 | doi = 10.1016/j.yjmcc.2011.10.011 }}</ref>

=== Genetics ===
Family history of ischemic heart disease or MI, particularly if one has a male first-degree relative (father, brother) who had a myocardial infarction before age 55 years, or a female first-degree relative (mother, sister) less than age 65 increases a person's risk of MI.<ref name="EUROPEAN2012" />

Genome-wide association studies have found 27 genetic variants that are associated with an increased risk of myocardial infarction.<ref name="Genomics of Cardiovascular Disease" /> The strongest association of MI has been found with [[Biology:Chromosome 9|chromosome 9]] on the short arm ''p'' at [[Biology:Locus (genetics)|locus]] 21, which contains genes CDKN2A and 2B, although the single nucleotide polymorphisms that are implicated are within a non-coding region.<ref name="Genomics of Cardiovascular Disease" /> The majority of these variants are in regions that have not been previously implicated in coronary artery disease. The following genes have an association with MI: PCSK9, SORT1, MIA3, [[Biology:WDR12|WDR12]], [[Biology:MRAS|MRAS]], [[Biology:PHACTR1|PHACTR1]], [[Medicine:Lipoprotein(a)|LPA]], TCF21, MTHFDSL, ZC3HC1, [[Biology:CDKN2A|CDKN2A]], [[Biology:CDKN2B|2B]], ABO, PDGF0, [[Biology:APOA5|APOA5]], MNF1ASM283, COL4A1, HHIPC1, SMAD3, [[Biology:ADAMTS7|ADAMTS7]], RAS1, [[Biology:SMG6|SMG6]], [[Biology:SNF8|SNF8]], LDLR, [[Biology:SLC5A3|SLC5A3]], [[Biology:MRPS6|MRPS6]], [[Biology:KCNE2|KCNE2]].<ref name="Genomics of Cardiovascular Disease">{{cite journal | vauthors = O'Donnell CJ, Nabel EG | title = Genomics of cardiovascular disease | journal = The New England Journal of Medicine | volume = 365 | issue = 22 | pages = 2098–109 | date = December 2011 | pmid = 22129254 | doi = 10.1056/NEJMra1105239 | doi-access =free  }}</ref>

=== Other ===
The risk of having a myocardial infarction increases with older age, low physical activity, and low [[Social:Socioeconomic status|socioeconomic status]].<ref name="EUROPEAN2012" /> Heart attacks appear to occur more commonly in the morning hours, especially between 6AM and noon.<ref name="Culic2007">{{cite journal | vauthors = Culić V | title = Acute risk factors for myocardial infarction | journal = International Journal of Cardiology | volume = 117 | issue = 2 | pages = 260–9 | date = April 2007 | pmid = 16860887 | doi = 10.1016/j.ijcard.2006.05.011 }}</ref> Evidence suggests that heart attacks are at least three times more likely to occur in the morning than in the late evening.<ref name="Shaw2009">{{cite journal | vauthors = Shaw E, Tofler GH | title = Circadian rhythm and cardiovascular disease | journal = Current Atherosclerosis Reports | volume = 11 | issue = 4 | pages = 289–95 | date = July 2009 | pmid = 19500492 | doi = 10.1007/s11883-009-0044-4 | s2cid = 43626425 }}</ref> [[Chemistry:Shift work|Shift work]] is also associated with a higher risk of MI.<ref name=Vyas2012>{{cite journal | vauthors = Vyas MV, Garg AX, Iansavichus AV, Costella J, Donner A, Laugsand LE, Janszky I, Mrkobrada M, Parraga G, Hackam DG | display-authors = 6 | title = Shift work and vascular events: systematic review and meta-analysis | journal = BMJ | volume = 345 | pages = e4800 | date = July 2012 | pmid = 22835925 | pmc = 3406223 | doi = 10.1136/bmj.e4800 }}</ref> One analysis has found an increase in heart attacks immediately following the start of daylight saving time.<ref>{{cite journal | vauthors = Janszky I, Ljung R | title = Shifts to and from daylight saving time and incidence of myocardial infarction | journal = The New England Journal of Medicine | volume = 359 | issue = 18 | pages = 1966–8 | date = October 2008 | pmid = 18971502 | doi = 10.1056/NEJMc0807104 | s2cid = 205040478 | doi-access = free }}</ref>

Women who use [[Chemistry:Combined oral contraceptive pill|combined oral contraceptive pill]]s have a modestly increased risk of myocardial infarction, especially in the presence of other risk factors.<ref>{{cite journal | vauthors = Roach RE, Helmerhorst FM, Lijfering WM, Stijnen T, Algra A, Dekkers OM | title = Combined oral contraceptives: the risk of myocardial infarction and ischemic stroke | journal = The Cochrane Database of Systematic Reviews | issue = 8 | pages = CD011054 | date = August 2015 | volume = 2015 | pmid = 26310586 | pmc = 6494192 | doi = 10.1002/14651858.CD011054.pub2 | hdl = 1874/340787 }}</ref> The use of non-steroidal anti inflammatory drugs (NSAIDs), even for as short as a week, increases risk.<ref>{{cite journal | vauthors = Bally M, Dendukuri N, Rich B, Nadeau L, Helin-Salmivaara A, Garbe E, Brophy JM | title = Risk of acute myocardial infarction with NSAIDs in real world use: bayesian meta-analysis of individual patient data | journal = BMJ | volume = 357 | pages = j1909 | date = May 2017 | pmid = 28487435 | pmc = 5423546 | doi = 10.1136/bmj.j1909 }}</ref>

[[Medicine:Endometriosis|Endometriosis]] in women under the age of 40 is an identified risk factor.<ref>{{cite journal | vauthors = Mu F, Rich-Edwards J, Rimm EB, Spiegelman D, Missmer SA | title = Endometriosis and Risk of Coronary Heart Disease | journal = Circulation: Cardiovascular Quality and Outcomes | volume = 9 | issue = 3 | pages = 257–64 | date = May 2016 | pmid = 27025928 | pmc = 4940126 | doi = 10.1161/CIRCOUTCOMES.115.002224 }}</ref>

[[Earth:Air pollution|Air pollution]] is also an important modifiable risk. Short-term exposure to air pollution such as [[Chemistry:Carbon monoxide|carbon monoxide]], [[Chemistry:Nitrogen dioxide|nitrogen dioxide]], and [[Chemistry:Sulfur dioxide|sulfur dioxide]] (but not [[Chemistry:Ozone|ozone]]) have been associated with MI and other acute cardiovascular events.<ref>{{cite journal | vauthors = Mustafic H, Jabre P, Caussin C, Murad MH, Escolano S, Tafflet M, Périer MC, Marijon E, Vernerey D, Empana JP, Jouven X | display-authors = 6 | title = Main air pollutants and myocardial infarction: a systematic review and meta-analysis | journal = JAMA | volume = 307 | issue = 7 | pages = 713–21 | date = February 2012 | pmid = 22337682 | doi = 10.1001/jama.2012.126 | doi-access =  }}</ref> For sudden cardiac deaths, every increment of 30 units in Pollutant Standards Index correlated with an 8% increased risk of out-of-hospital cardiac arrest on the day of exposure.<ref>{{cite journal | vauthors = Ho AF, Wah W, Earnest A, Ng YY, Xie Z, Shahidah N, Yap S, Pek PP, Liu N, Lam SS, Ong ME | display-authors = 6 | title = Health impacts of the Southeast Asian haze problem – A time-stratified case crossover study of the relationship between ambient air pollution and sudden cardiac deaths in Singapore | journal = International Journal of Cardiology | volume = 271 | pages = 352–358 | date = November 2018 | pmid = 30223374 | doi = 10.1016/j.ijcard.2018.04.070 | s2cid = 52282745 }}</ref> Extremes of temperature are also associated.<ref>{{cite journal | vauthors = Sun Z, Chen C, Xu D, Li T | title = Effects of ambient temperature on myocardial infarction: A systematic review and meta-analysis | journal = Environmental Pollution | volume = 241 | pages = 1106–1114 | date = October 2018 | pmid = 30029319 | doi = 10.1016/j.envpol.2018.06.045 | s2cid = 51705159 }}</ref>

A number of acute and chronic infections including ''[[Biology:Chlamydophila pneumoniae|Chlamydophila pneumoniae]]'', [[Medicine:Influenza|influenza]], ''Helicobacter pylori'', and ''[[Biology:Porphyromonas gingivalis|Porphyromonas gingivalis]]'' among others have been linked to atherosclerosis and myocardial infarction.<ref name=Chat2012 /> As of 2013, there is no evidence of benefit from [[Chemistry:Antibiotic|antibiotic]]s or [[Biology:Vaccination|vaccination]], however, calling the association into question.<ref name=Chat2012>{{cite journal | vauthors = Chatzidimitriou D, Kirmizis D, Gavriilaki E, Chatzidimitriou M, Malisiovas N | title = Atherosclerosis and infection: is the jury still not in? | journal = Future Microbiology | volume = 7 | issue = 10 | pages = 1217–30 | date = October 2012 | pmid = 23030426 | doi = 10.2217/fmb.12.87 }}</ref><ref name=Char2013>{{cite journal | vauthors = Charakida M, Tousoulis D | title = Infections and atheromatous plaque: current therapeutic implications | journal = Current Pharmaceutical Design | volume = 19 | issue = 9 | pages = 1638–50 | year = 2013 | pmid = 23016720 | doi = 10.2174/138161213805219658 }}</ref> Myocardial infarction can also occur as a late consequence of [[Medicine:Kawasaki disease|Kawasaki disease]].<ref name=Sanchez2014>{{cite journal | vauthors = Sánchez-Manubens J, Bou R, Anton J | title = Diagnosis and classification of Kawasaki disease | journal = Journal of Autoimmunity | volume = 48-49 | pages = 113–7 | date = February 2014 | pmid = 24485156 | doi = 10.1016/j.jaut.2014.01.010 }}</ref>

Calcium deposits in the coronary arteries can be detected with [[CT scan]]s. Calcium seen in coronary arteries can provide predictive information beyond that of classical risk factors.<ref>{{cite journal | vauthors = Hulten EA, Carbonaro S, Petrillo SP, Mitchell JD, Villines TC | title = Prognostic value of cardiac computed tomography angiography: a systematic review and meta-analysis | journal = Journal of the American College of Cardiology | volume = 57 | issue = 10 | pages = 1237–47 | date = March 2011 | pmid = 21145688 | doi = 10.1016/j.jacc.2010.10.011 | doi-access = free }}</ref> [[Medicine:Hyperhomocysteinemia|High blood levels of the amino acid homocysteine]] is associated with premature atherosclerosis;<ref>{{cite journal | vauthors = Clarke R, Halsey J, Bennett D, Lewington S | title = Homocysteine and vascular disease: review of published results of the homocysteine-lowering trials | journal = Journal of Inherited Metabolic Disease | volume = 34 | issue = 1 | pages = 83–91 | date = February 2011 | pmid = 21069462 | doi = 10.1007/s10545-010-9235-y | s2cid = 8714058 }}</ref> whether elevated homocysteine in the normal range is causal is controversial.<ref>{{cite journal | vauthors = Lonn E | title = Homocysteine in the prevention of ischemic heart disease, stroke and venous thromboembolism: therapeutic target or just another distraction? | journal = Current Opinion in Hematology | volume = 14 | issue = 5 | pages = 481–7 | date = September 2007 | pmid = 17934354 | doi = 10.1097/MOH.0b013e3282c48bd8 | s2cid = 8734056 }}</ref>

In people without evident [[Medicine:Coronary artery disease|coronary artery disease]], possible causes for the myocardial infarction are coronary spasm or [[Medicine:Spontaneous coronary artery dissection|coronary artery dissection]].<ref>{{cite journal | vauthors = Agewall S, Beltrame JF, Reynolds HR, Niessner A, Rosano G, Caforio AL, De Caterina R, Zimarino M, Roffi M, Kjeldsen K, Atar D, Kaski JC, Sechtem U, Tornvall P | display-authors = 6 | title = ESC working group position paper on myocardial infarction with non-obstructive coronary arteries | journal = European Heart Journal | volume = 38 | issue = 3 | pages = 143–153 | date = January 2017 | pmid = 28158518 | doi = 10.1093/eurheartj/ehw149 | doi-access = free }}</ref>

== Mechanism ==

=== Atherosclerosis ===
[[File:Heart attack animation.ogv|thumb|The animation shows plaque buildup or a [[Medicine:Vasospasm|coronary artery spasm]] can lead to a heart attack and how blocked blood flow in a coronary artery can lead to a heart attack.]]
{{Further|Medicine:Atherosclerosis}}
<!--Introduction-->The most common cause of a myocardial infarction is the rupture of an atherosclerotic plaque on an [[Biology:Artery|artery]] supplying heart muscle.<ref name='ESC STEMI' /><ref name="Reed2017">{{cite journal | vauthors = Reed GW, Rossi JE, Cannon CP | title = Acute myocardial infarction | journal = Lancet | volume = 389 | issue = 10065 | pages = 197–210 | date = January 2017 | pmid = 27502078 | doi = 10.1016/S0140-6736(16)30677-8 | s2cid = 33523662 }}</ref> Plaques can become unstable, rupture, and additionally promote the formation of a [[Medicine:Thrombus|blood clot]] that blocks the artery; this can occur in minutes. Blockage of an artery can lead to tissue death in tissue being supplied by that artery.<ref name=Davidsons2010B /> Atherosclerotic plaques are often present for decades before they result in symptoms.<ref name=Davidsons2010B>{{cite book | vauthors = Colledge NR, Walker BR, Ralston SH, Davidson LS |title=Davidson's principles and practice of medicine|date=2010|publisher=Churchill Livingstone/Elsevier|location=Edinburgh|isbn=978-0-7020-3085-7|edition=21st|pages=577–9}}</ref>

<!--Details-->The gradual buildup of [[Chemistry:Cholesterol|cholesterol]] and fibrous tissue in plaques in the wall of the coronary arteries or other arteries, typically over decades, is termed [[Medicine:Atherosclerosis|atherosclerosis]].<ref name="pmid20065951">{{cite journal | vauthors = Woollard KJ, Geissmann F | title = Monocytes in atherosclerosis: subsets and functions | journal = Nature Reviews. Cardiology | volume = 7 | issue = 2 | pages = 77–86 | date = February 2010 | pmid = 20065951 | pmc = 2813241 | doi = 10.1038/nrcardio.2009.228 }}</ref> Atherosclerosis is characterized by progressive inflammation of the walls of the arteries.<ref name=Davidsons2010B /> Inflammatory cells, particularly [[Biology:Macrophage|macrophage]]s, move into affected arterial walls. Over time, they become laden with cholesterol products, particularly LDL, and become [[Biology:Foam cell|foam cell]]s. A [[Medicine:Atheroma|cholesterol core]] forms as foam cells die. In response to [[Biology:Growth factor|growth factor]]s secreted by macrophages, [[Biology:Smooth muscle|smooth muscle]] and other cells move into the plaque and act to stabilize it. A stable plaque may have a thick fibrous cap with [[Biology:Calcification|calcification]]. If there is ongoing inflammation, the cap may be thin or ulcerate. Exposed to the pressure associated with blood flow, plaques, especially those with a thin lining, may rupture and trigger the formation of a blood clot (thrombus).<ref name=Davidsons2010B /> The cholesterol crystals have been associated with plaque rupture through mechanical injury and inflammation.<ref>{{cite journal | vauthors = Janoudi A, Shamoun FE, Kalavakunta JK, Abela GS | title = Cholesterol crystal induced arterial inflammation and destabilization of atherosclerotic plaque | journal = European Heart Journal | volume = 37 | issue = 25 | pages = 1959–67 | date = July 2016 | pmid = 26705388 | doi = 10.1093/eurheartj/ehv653 | doi-access = free }}</ref>

=== {{Anchor|Other causes}} Other causes ===
Atherosclerotic disease is not the only cause of myocardial infarction, but it may exacerbate or contribute to other causes. A myocardial infarction may result from a heart with a limited blood supply subject to increased oxygen demands, such as in fever, [[Medicine:Tachycardia|a fast heart rate]], [[Medicine:Hyperthyroidism|hyperthyroidism]], [[Medicine:Anemia|too few red blood cells in the bloodstream]], or [[Medicine:Hypotension|low blood pressure]]. Damage or failure of procedures such as [[Medicine:Percutaneous coronary intervention|percutaneous coronary intervention]] or coronary artery bypass grafts may cause a myocardial infarction. Spasm of coronary arteries, such as Prinzmetal's angina may cause blockage.<ref name=THIRDDEF /><ref name=Harrisons2015 />

=== Tissue death ===
[[File:Heart ant wall infarction.jpg|thumb|Cross section showing anterior left ventricle wall infarction]]
If impaired blood flow to the heart lasts long enough, it triggers a process called the [[Biology:Ischemic cascade|ischemic cascade]]; the heart cells in the territory of the blocked coronary artery die (infarction), chiefly through [[Biology:Necrosis|necrosis]], and do not grow back. A [[Biology:Collagen|collagen]] scar forms in their place.<ref name=Davidsons2010B /> When an artery is blocked, cells lack [[Chemistry:Oxygen|oxygen]], needed to produce [[Chemistry:Adenosine triphosphate|ATP]] in [[Biology:Mitochondria|mitochondria]]. ATP is required for the maintenance of electrolyte balance, particularly through the Na/K ATPase. This leads to an ischemic cascade of intracellular changes, necrosis and [[Biology:Apoptosis|apoptosis]] of affected cells.<ref name="BUJA2005">{{cite journal | vauthors = Buja LM | title = Myocardial ischemia and reperfusion injury | journal = Cardiovascular Pathology | volume = 14 | issue = 4 | pages = 170–5 | date = July 2005 | pmid = 16009313 | doi = 10.1016/j.carpath.2005.03.006 }}</ref>

Cells in the area with the worst blood supply, just below the inner surface of the heart (endocardium), are most susceptible to damage.<ref>{{cite journal | vauthors = Algranati D, Kassab GS, Lanir Y | title = Why is the subendocardium more vulnerable to ischemia? A new paradigm | journal = American Journal of Physiology. Heart and Circulatory Physiology | volume = 300 | issue = 3 | pages = H1090–100 | date = March 2011 | pmid = 21169398 | pmc = 3064294 | doi = 10.1152/ajpheart.00473.2010 }}</ref><ref name="BOLOOKI2010">{{cite web| vauthors = Bolooki HM, Askari A |title=Acute Myocardial Infarction |url= http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/cardiology/acute-myocardial-infarction/ |website=www.clevelandclinicmeded.com|access-date=24 May 2017 |date=August 2010 |url-status=live |archive-url=https://web.archive.org/web/20170428050921/http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/cardiology/acute-myocardial-infarction/|archive-date=28 April 2017}}</ref> Ischemia first affects this region, the ''subendocardial'' region, and tissue begins to die within 15–30 minutes of loss of blood supply.<ref name="AARONSON2013">{{cite book| vauthors = Aaronson PI, Ward JP, Connolly MJ |title=The cardiovascular system at a glance|date=2013|publisher=Wiley-Blackwell|location=Chichester, West Sussex|isbn=978-0-470-65594-8|pages=88–89|edition=4th}}</ref> The dead tissue is surrounded by a zone of potentially reversible ischemia that progresses to become a full-thickness ''transmural'' infarct.<ref name=BUJA2005 /><ref name=AARONSON2013 /> The initial "wave" of infarction can take place over 3–4 hours.<ref name=Davidsons2010B /><ref name=BUJA2005 /> These changes are seen on gross pathology and cannot be predicted by the presence or absence of Q waves on an ECG.<ref name=BOLOOKI2010 /> The position, size and extent of an infarct depends on the affected artery, totality of the blockage, duration of the blockage, the presence of [[Biology:Collateralization|collateral blood vessels]], oxygen demand, and success of interventional procedures.<ref name=Harrisons2015 /><ref name=Reed2017 />

Tissue death and [[Medicine:Myocardial scarring|myocardial scarring]] alter the normal conduction pathways of the heart and weaken affected areas. The size and location put a person at risk of [[Medicine:Heart arrhythmia|abnormal heart rhythms (arrhythmias)]] or [[Medicine:Heart block|heart block]], [[Medicine:Ventricular aneurysm|aneurysm of the heart ventricles]], inflammation of the heart wall following infarction, and rupture of the heart wall that can have catastrophic consequences.<ref name=Reed2017 /><ref name="Kutty2013">{{cite journal | vauthors = Kutty RS, Jones N, Moorjani N | title = Mechanical complications of acute myocardial infarction | journal = Cardiology Clinics | volume = 31 | issue = 4 | pages = 519–31, vii–viii | date = November 2013 | pmid = 24188218 | doi = 10.1016/j.ccl.2013.07.004 | type = Review }}</ref>

Injury to the myocardium also occurs during re-perfusion. This might manifest as ventricular arrhythmia. The re-perfusion injury is a consequence of the calcium and sodium uptake from the cardiac cells and the release of oxygen radicals during reperfusion. No-reflow phenomenon—when blood is still unable to be distributed to the affected myocardium despite clearing the occlusion—also contributes to myocardial injury. Topical endothelial swelling is one of many factors contributing to this phenomenon.<ref name=KlonerHale>{{cite book| vauthors = Kloner R, Hale SL |chapter = Reperfusion Injury: Prevention and Management|pages=286–288| veditors = Morrow DA |title=Myocardial Infarction: A Companion to Braunwald's Heart Disease|url=https://books.google.com/books?id=0TzrjwEACAAJ|date=15 September 2016|publisher=Elsevier|isbn=978-0-323-35943-6}}</ref>

== Diagnosis ==
{{Main|Biology:Myocardial infarction diagnosis}}

[[File:AMI scheme.png|thumb|Diagram showing the [[Medicine:Coronary circulation|blood supply to the heart]] by the two major blood vessels, the left and right coronary arteries (labelled LCA and RCA). A myocardial infarction (2) has occurred with blockage of a branch of the left coronary artery (1).]]

=== Criteria ===
A myocardial infarction, according to current consensus, is defined by elevated cardiac biomarkers with a rising or falling trend and at least one of the following:<ref>{{cite journal | vauthors = Thygesen K, Alpert JS, Jaffe AS, Chaitman BR, Bax JJ, Morrow DA, White HD | title = Fourth universal definition of myocardial infarction (2018) | journal = European Heart Journal | volume = 40 | issue = 3 | pages = 237–269 | date = January 2019 | pmid = 30165617 | doi = 10.1093/eurheartj/ehy462 | doi-access = free | hdl = 10044/1/73052 | hdl-access = free }}</ref>
* Symptoms relating to ischemia
* Changes on an electrocardiogram (ECG), such as [[Medicine:ST segment|ST segment]] changes, new [[Medicine:Left bundle branch block|left bundle branch block]], or pathologic [[Medicine:QRS complex#Q wave|Q waves]]
* Changes in the motion of the heart wall on imaging
* Demonstration of a thrombus on angiogram or at autopsy.

=== {{Anchor|STEMI}}{{Anchor|NSTEMI}}Types ===
A myocardial infarction is usually clinically classified as an ST-elevation MI (STEMI) or a non-ST elevation MI (NSTEMI). These are based on [[Medicine:ST elevation|ST elevation]], a portion of a heartbeat graphically recorded on an ECG.<ref name=THIRDDEF /> STEMIs make up about 25–40% of myocardial infarctions.<ref name=AHA2013 /> A more explicit classification system, based on international consensus in 2012, also exists. This classifies myocardial infarctions into five types:<ref name=THIRDDEF />
# Spontaneous MI related to plaque erosion and/or rupture fissuring, or dissection
# MI related to ischemia, such as from increased oxygen demand or decreased supply, e.g., coronary artery spasm, coronary embolism, anemia, arrhythmias, high blood pressure, or low blood pressure
# Sudden unexpected cardiac death, including cardiac arrest, where symptoms may suggest MI, an ECG may be taken with suggestive changes, or a blood clot is found in a coronary artery by angiography and/or at autopsy, but where blood samples could not be obtained, or at a time before the appearance of cardiac biomarkers in the blood
# Associated with coronary angioplasty or [[Medicine:Stent|stent]]s
#* Associated with [[Medicine:Percutaneous coronary intervention|percutaneous coronary intervention]] (PCI)
#* Associated with stent thrombosis as documented by angiography or at autopsy
# Associated with CABG
# Associated with [[Medicine:Spontaneous coronary artery dissection|spontaneous coronary artery dissection]] in young, fit women

=== Cardiac biomarkers ===
<!--Troponin-->
There are many different [[Biology:Biomarker|biomarker]]s used to determine the presence of cardiac muscle damage. [[Biology:Troponin|Troponin]]s, measured through a blood test, are considered to be the best,<ref name=AHA2013 /> and are preferred because they have greater [[Sensitivity and specificity|sensitivity and specificity]] for measuring injury to the heart muscle than other tests.<ref name="Reed2017" /> A rise in troponin occurs within 2–3 hours of injury to the heart muscle, and peaks within 1–2 days. The level of the troponin, as well as a change over time, are useful in measuring and diagnosing or excluding myocardial infarctions, and the diagnostic accuracy of troponin testing is improving over time.<ref name="Reed2017" /> One high-sensitivity cardiac troponin can rule out a heart attack as long as the ECG is normal.<ref>{{cite journal | vauthors = Pickering JW, Than MP, Cullen L, Aldous S, Ter Avest E, Body R, Carlton EW, Collinson P, Dupuy AM, Ekelund U, Eggers KM, Florkowski CM, Freund Y, George P, Goodacre S, Greenslade JH, Jaffe AS, Lord SJ, Mokhtari A, Mueller C, Munro A, Mustapha S, Parsonage W, Peacock WF, Pemberton C, Richards AM, Sanchis J, Staub LP, Troughton R, Twerenbold R, Wildi K, Young J | display-authors = 6 | title = Rapid Rule-out of Acute Myocardial Infarction With a Single High-Sensitivity Cardiac Troponin T Measurement Below the Limit of Detection: A Collaborative Meta-analysis | journal = Annals of Internal Medicine | volume = 166 | issue = 10 | pages = 715–724 | date = May 2017 | pmid = 28418520 | doi = 10.7326/M16-2562 | url = https://www.research.manchester.ac.uk/portal/en/publications/rapid-ruleout-of-acute-myocardial-infarction-with-a-single-highsensitivity-cardiac-troponin-t-measurement-below-the-limit-of-detection(0e2cb8e0-229a-446b-9389-7fa319a649d4).html }}</ref><ref>{{cite journal | vauthors = Chapman AR, Lee KK, McAllister DA, Cullen L, Greenslade JH, Parsonage W, Worster A, Kavsak PA, Blankenberg S, Neumann J, Sörensen NA, Westermann D, Buijs MM, Verdel GJ, Pickering JW, Than MP, Twerenbold R, Badertscher P, Sabti Z, Mueller C, Anand A, Adamson P, Strachan FE, Ferry A, Sandeman D, Gray A, Body R, Keevil B, Carlton E, Greaves K, Korley FK, Metkus TS, Sandoval Y, Apple FS, Newby DE, Shah AS, Mills NL | display-authors = 6 | title = Association of High-Sensitivity Cardiac Troponin I Concentration With Cardiac Outcomes in Patients With Suspected Acute Coronary Syndrome | journal = JAMA | volume = 318 | issue = 19 | pages = 1913–1924 | date = November 2017 | pmid = 29127948 | pmc = 5710293 | doi = 10.1001/jama.2017.17488 }}</ref>

<!--Other tests-->
Other tests, such as CK-MB or [[Biology:Myoglobin|myoglobin]], are discouraged.<ref name=AHANSTEMI2014>{{cite journal | vauthors = Amsterdam EA, Wenger NK, Brindis RG, Casey DE, Ganiats TG, Holmes DR, Jaffe AS, Jneid H, Kelly RF, Kontos MC, Levine GN, Liebson PR, Mukherjee D, Peterson ED, Sabatine MS, Smalling RW, Zieman SJ | display-authors = 6 | title = 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines | journal = Circulation | volume = 130 | issue = 25 | pages = e344–426 | date = December 2014 | pmid = 25249585 | doi = 10.1161/CIR.0000000000000134 | doi-access = free }}</ref> CK-MB is not as specific as troponins for acute myocardial injury, and may be elevated with past cardiac surgery, inflammation or electrical cardioversion; it rises within 4–8 hours and returns to normal within 2–3 days.<ref name=Harrisons2015 /> [[Biology:Copeptin|Copeptin]] may be useful to rule out MI rapidly when used along with troponin.<ref>{{cite journal | vauthors = Lipinski MJ, Escárcega RO, D'Ascenzo F, Magalhães MA, Baker NC, Torguson R, Chen F, Epstein SE, Miró O, Llorens P, Giannitsis E, Lotze U, Lefebvre S, Sebbane M, Cristol JP, Chenevier-Gobeaux C, Meune C, Eggers KM, Charpentier S, Twerenbold R, Mueller C, Biondi-Zoccai G, Waksman R | display-authors = 6 | title = A systematic review and collaborative meta-analysis to determine the incremental value of copeptin for rapid rule-out of acute myocardial infarction | journal = The American Journal of Cardiology | volume = 113 | issue = 9 | pages = 1581–91 | date = May 2014 | pmid = 24731654 | doi = 10.1016/j.amjcard.2014.01.436 }}</ref>

=== Electrocardiogram ===
[[File:Inferior and RtV MI 12 lead.jpg|thumb|upright=1.6|A 12-lead ECG showing an inferior STEMI due to reduced perfusion through the right coronary artery. Elevation of the ST segment can be seen in leads II, III and aVF.]]
Electrocardiograms (ECGs) are a series of leads placed on a person's chest that measure electrical activity associated with contraction of the heart muscle.<ref name=Davidsons2010C /> The taking of an ECG is an important part of the workup of an AMI,<ref name=THIRDDEF /> and ECGs are often not just taken once but may be repeated over minutes to hours, or in response to changes in signs or symptoms.<ref name=THIRDDEF />

ECG readouts product a waveform with different labelled features.<ref name=Davidsons2010C>{{cite book | vauthors = Colledge NR, Walker BR, Ralston SH, Davidson LS |title=Davidson's principles and practice of medicine|date=2010|publisher=Churchill Livingstone/Elsevier|location=Edinburgh|isbn=978-0-7020-3085-7|edition=21st|pages=529–30}}</ref> In addition to a rise in biomarkers, a rise in the [[Medicine:ST segment|ST segment]], changes in the shape or flipping of [[Medicine:T wave|T wave]]s, new [[Medicine:QRS complex#Q wave|Q waves]], or a new [[Medicine:Left bundle branch block|left bundle branch block]] can be used to diagnose an AMI.<ref name=THIRDDEF /> In addition, [[Medicine:ST elevation|ST elevation]] can be used to diagnose an ST segment myocardial infarction (STEMI). A rise must be new in V2 and V3 ≥2&nbsp;mm (0,2 mV) for males or ≥1.5&nbsp;mm (0.15 mV) for females or ≥1&nbsp;mm (0.1&nbsp;mV) in two other adjacent chest or limb leads.<ref name=AHA2013 /><ref name=THIRDDEF /> ST elevation is associated with infarction, and may be preceded by changes indicating ischemia, such as ST depression or inversion of the T waves.<ref name=Davidsons2010C /> Abnormalities can help differentiate the location of an infarct, based on the leads that are affected by changes.<ref name=Davidsons2010 /> Early STEMIs may be preceded by peaked T waves.<ref name=AHA2013 /> Other ECG abnormalities relating to complications of acute myocardial infarctions may also be evident, such as [[Medicine:Atrial fibrillation|atrial]] or [[Medicine:Ventricular fibrillation|ventricular fibrillation]].<ref>{{Cite book|title=Harrison's principles of internal medicine| vauthors = Kasper DL, Fauci AS, Hauser SL, Longo DL, Jameson JL, Loscalzo J |publisher=McGraw Hill Education |year=2015 |isbn=978-0-07-180215-4 |pages=1457 |oclc=923181481}}</ref>
[[File:ECG V2-4 ST change.jpg|thumb|ECG : AMI with ST elevation in V2-4]]

=== Imaging ===
Noninvasive imaging plays an important role in the diagnosis and characterisation of myocardial infarction.<ref name=THIRDDEF /> Tests such as chest X-rays can be used to explore and exclude alternate causes of a person's symptoms.<ref name=THIRDDEF /> [[Medicine:Echocardiography|Echocardiography]] may assist in modifying clinical suspicion of ongoing myocardial infarction in patients that can't be ruled out or ruled in following initial [[Biology:Electrocardiography|ECG]] and [[Biology:Troponin|Troponin]] testing.<ref name="auto">{{cite journal | vauthors = Collet JP, Thiele H, Barbato E, Barthélémy O, Bauersachs J, Bhatt DL, Dendale P, Dorobantu M, Edvardsen T, Folliguet T, Gale CP, Gilard M, Jobs A, Jüni P, Lambrinou E, Lewis BS, Mehilli J, Meliga E, Merkely B, Mueller C, Roffi M, Rutten FH, Sibbing D, Siontis GC | display-authors = 6 | title = 2020 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation | journal = European Heart Journal | volume = 42 | issue = 14 | pages = 1289–1367 | date = April 2021 | pmid = 32860058 | doi = 10.1093/eurheartj/ehaa575 | doi-access = free }}</ref> [[Chemistry:Myocardial perfusion imaging|Myocardial perfusion imaging]] has no role in the acute diagnostic algorithm; however, it can confirm a clinical suspicion of Chronic Coronary Syndrome when the patient's history, physical examination (including [[Medicine:Cardiac examination|cardiac examination]]) ECG, and cardiac biomarkers suggest coronary artery disease.<ref name="WISELY2017" />

[[Medicine:Echocardiography|Echocardiography]], an [[Physics:Ultrasound|ultrasound]] scan of the heart, is able to visualize the heart, its size, shape, and any abnormal motion of the heart walls as they beat that may indicate a myocardial infarction. The flow of blood can be imaged, and contrast dyes may be given to improve image.<ref name=THIRDDEF /> Other scans using [[Physics:Radioactive|radioactive]] contrast include SPECT CT-scans using thallium, [[Chemistry:Technetium (99mTc) sestamibi|sestamibi]] (MIBI scans) or tetrofosmin; or a PET scan using [[Chemistry:Fludeoxyglucose (18F)|Fludeoxyglucose]] or [[Physics:Rubidium-82|rubidium-82]].<ref name=THIRDDEF /> These [[Medicine:Nuclear medicine|nuclear medicine]] scans can visualize the perfusion of heart muscle.<ref name=THIRDDEF /> SPECT may also be used to determine viability of tissue, and whether areas of ischemia are inducible.<ref name=THIRDDEF /><ref>{{cite journal | vauthors = Schinkel AF, Valkema R, Geleijnse ML, Sijbrands EJ, Poldermans D | title = Single-photon emission computed tomography for assessment of myocardial viability | journal = EuroIntervention | volume = 6 | issue = Supplement G | pages = G115–22 | date = May 2010 | pmid = 20542817 }}</ref>

Medical societies and professional guidelines recommend that the physician confirm a person is at high risk for Chronic Coronary Syndrome before conducting diagnostic non-invasive imaging tests to make a diagnosis,<ref name="WISELY2017">{{cite web|title=American College of Cardiology|url=http://www.choosingwisely.org/societies/american-college-of-cardiology/|website=www.choosingwisely.org|publisher=Choosing Wisely|access-date=24 May 2017|date=28 February 2017|url-status=live|archive-url=https://web.archive.org/web/20170728125746/http://www.choosingwisely.org/societies/american-college-of-cardiology/|archive-date=28 July 2017}}</ref><ref name=NICECG94>{{NICE|cg94|Unstable angina and NSTEMI|2010}}</ref><ref name="auto"/> as such tests are unlikely to change management and result in increased costs.<ref name="WISELY2017" /> Patients who have a normal ECG and who are able to exercise, for example, most likely do not merit routine imaging.<ref name="WISELY2017" />

<gallery widths="200px" heights="200px">
File:UOTW 36 - Ultrasound of the Week 1.webm|Poor movement of the heart due to an MI as seen on ultrasound<ref name=UOTW36>{{cite web|title=UOTW #36 – Ultrasound of the Week|url=https://www.ultrasoundoftheweek.com/uotw-36/|website=Ultrasound of the Week|access-date=27 May 2017|date=5 February 2015|url-status=live|archive-url=https://web.archive.org/web/20170509115806/https://www.ultrasoundoftheweek.com/uotw-36/|archive-date=9 May 2017}}</ref>
File:UOTW 36 - Ultrasound of the Week 2.webm|Pulmonary edema due to an MI as seen on ultrasound<ref name=UOTW36 />
</gallery>

=== Differential diagnosis ===
There are many causes of [[Medicine:Chest pain|chest pain]], which can originate from the heart, [[Medicine:Lung|lung]]s, [[Biology:Gastrointestinal tract|gastrointestinal tract]], aorta, and other muscles, bones and nerves surrounding the chest.<ref name=Davidsons2010D /> In addition to myocardial infarction, other causes include angina, insufficient blood supply ([[Medicine:Ischemia|ischemia]]) to the heart muscles without evidence of cell death, [[Medicine:Gastroesophageal reflux disease|gastroesophageal reflux disease]]; [[Medicine:Pulmonary embolism|pulmonary embolism]], tumors of the lungs, [[Medicine:Pneumonia|pneumonia]], [[Medicine:Rib fracture|rib fracture]], costochondritis, [[Medicine:Heart failure|heart failure]] and other musculoskeletal injuries.<ref name="Davidsons2010D">{{cite book | vauthors = Colledge NR, Walker BR, Ralston SH, Davidson LS |title=Davidson's principles and practice of medicine|date=2010|publisher=Churchill Livingstone/Elsevier|location=Edinburgh|isbn=978-0-7020-3085-7|edition=21st|pages=535, 539}}</ref><ref name="THIRDDEF" /> Rarer severe differential diagnoses include [[Medicine:Aortic dissection|aortic dissection]], esophageal rupture, tension pneumothorax, and pericardial effusion causing [[Medicine:Cardiac tamponade|cardiac tamponade]].<ref name="pmid16199332">{{cite journal | vauthors = Boie ET | title = Initial evaluation of chest pain | journal = Emergency Medicine Clinics of North America | volume = 23 | issue = 4 | pages = 937–57 | date = November 2005 | pmid = 16199332 | doi = 10.1016/j.emc.2005.07.007 }}</ref> The chest pain in an MI may mimic heartburn.<ref name='ESC STEMI' /> Causes of sudden-onset breathlessness generally involve the lungs or heart – including [[Medicine:Pulmonary edema|pulmonary edema]], pneumonia, [[Medicine:Allergy|allergic]] reactions and [[Medicine:Asthma|asthma]], and pulmonary embolus, acute respiratory distress syndrome and metabolic acidosis.<ref name=Davidsons2010D /> There are many different causes of fatigue, and myocardial infarction is not a common cause.<ref>{{cite web|title=Assessment of fatigue|url=http://bestpractice.bmj.com/best-practice/monograph/571/diagnosis/differential-diagnosis.html|website=BMJ Best Practice|access-date=6 June 2017|date=17 August 2016}}</ref>

== Prevention ==
There is a large crossover between the lifestyle and activity recommendations to prevent a myocardial infarction, and those that may be adopted as secondary prevention after an initial myocardial infarction,<ref name=Reed2017 /> because of shared risk factors and an aim to reduce atherosclerosis affecting heart vessels.<ref name=Harrisons2015 /> The [[Medicine:Influenza vaccine|influenza vaccine]] also appear to protect against myocardial infarction with a benefit of 15 to 45%.<ref>{{cite journal | vauthors = MacIntyre CR, Mahimbo A, Moa AM, Barnes M | title = Influenza vaccine as a coronary intervention for prevention of myocardial infarction | journal = Heart | volume = 102 | issue = 24 | pages = 1953–1956 | date = December 2016 | pmid = 27686519 | pmc = 5256393 | doi = 10.1136/heartjnl-2016-309983 }}</ref>

=== Primary prevention ===
==== Lifestyle ====
Physical activity can reduce the risk of cardiovascular disease, and people at risk are advised to engage in 150 minutes of moderate or 75 minutes of vigorous intensity [[Medicine:Aerobic exercise|aerobic exercise]] a week.<ref name=NICECG181 /> Keeping a healthy weight, drinking alcohol within the recommended limits, and quitting smoking reduce the risk of cardiovascular disease.<ref name=NICECG181 />

<!--Diet-->Substituting [[Chemistry:Unsaturated fat|unsaturated fat]]s such as [[Biology:Olive oil|olive oil]] and [[Biology:Rapeseed oil|rapeseed oil]] instead of saturated fats may reduce the risk of myocardial infarction,<ref name=":1" /> although there is not universal agreement.<ref name=Chow2014 /> Dietary modifications are recommended by some national authorities, with recommendations including increasing the intake of wholegrain starch, reducing sugar intake (particularly of refined sugar), consuming five portions of fruit and vegetables daily, consuming two or more portions of fish per week, and consuming 4–5 portions of unsalted [[Biology:Nut (fruit)|nuts]], [[Biology:Seed|seed]]s, or [[Biology:Legume|legume]]s per week.<ref name=NICECG181 /> The dietary pattern with the greatest support is the Mediterranean diet.<ref>{{cite journal | vauthors = Stradling C, Hamid M, Taheri S, Thomas GN | title = A review of dietary influences on cardiovascular health: part 2: dietary patterns | journal = Cardiovascular & Hematological Disorders Drug Targets | volume = 14 | issue = 1 | pages = 50–63 | date = 2014 | pmid = 24993125 | doi = 10.2174/1871529x14666140701095426 }}</ref> [[Chemistry:Vitamin|Vitamin]]s and mineral supplements are of no proven benefit,<ref>{{cite journal | vauthors = Fortmann SP, Burda BU, Senger CA, Lin JS, Whitlock EP | title = Vitamin and mineral supplements in the primary prevention of cardiovascular disease and cancer: An updated systematic evidence review for the U.S. Preventive Services Task Force | journal = Annals of Internal Medicine | volume = 159 | issue = 12 | pages = 824–34 | date = December 2013 | pmid = 24217421 | doi = 10.7326/0003-4819-159-12-201312170-00729 | doi-access =  | s2cid = 17366251 }}</ref> and neither are plant stanols or [[Chemistry:Phytosterol|sterols]].<ref name=NICECG181>{{NICE|181|Lipid modification: cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease|2014}}</ref>

Public health measures may also act at a population level to reduce the risk of myocardial infarction, for example by reducing unhealthy diets (excessive salt, saturated fat, and trans-fat) including food labeling and marketing requirements as well as requirements for catering and restaurants and stimulating physical activity. This may be part of regional cardiovascular disease prevention programs or through the [[Social:Health impact assessment|health impact assessment]] of regional and local plans and policies.<ref name=NICEPH25>{{cite web | vauthors=McPherson K, et al. | title=Prevention of cardiovascular disease – NICE public health guidance 25 | publisher=[[Organization:National Institute for Health and Care Excellence|National Institute for Health and Care Excellence]] | location=London | date=June 2010 | url=http://guidance.nice.org.uk/ph25 | url-status=live | archive-url=https://web.archive.org/web/20140329171156/http://guidance.nice.org.uk/PH25 | archive-date=2014-03-29 }}</ref>

Most guidelines recommend combining different preventive strategies. A 2015 Cochrane Review found some evidence that such an approach might help with&nbsp;[[Physics:Blood pressure|blood pressure]],&nbsp;[[Body mass index|body mass index]]&nbsp;and&nbsp;waist circumference. However, there was insufficient evidence to show an effect on mortality or actual cardio-vascular events.<ref>{{cite journal | vauthors = Ebrahim S, Taylor F, Ward K, Beswick A, Burke M, Davey Smith G | title = Multiple risk factor interventions for primary prevention of coronary heart disease | journal = The Cochrane Database of Systematic Reviews | issue = 1 | pages = CD001561 | date = January 2011 | pmid = 21249647 | pmc = 4160097 | doi = 10.1002/14651858.cd001561.pub3 }}</ref>

==== Medication ====
[[Biology:Statin|Statin]]s, drugs that act to lower blood cholesterol, decrease the incidence and mortality rates of myocardial infarctions.<ref>{{cite journal | vauthors = Taylor F, Huffman MD, Macedo AF, Moore TH, Burke M, Davey Smith G, Ward K, Ebrahim S | display-authors = 6 | title = Statins for the primary prevention of cardiovascular disease | journal = The Cochrane Database of Systematic Reviews | volume = 1 | issue = 1 | pages = CD004816 | date = January 2013 | pmid = 23440795 | pmc = 6481400 | doi = 10.1002/14651858.CD004816.pub5 }}</ref> They are often recommended in those at an elevated risk of cardiovascular diseases.<ref name=NICECG181 />

Aspirin has been studied extensively in people considered at increased risk of myocardial infarction. Based on numerous studies in different groups (e.g. people with or without diabetes), there does not appear to be a benefit strong enough to outweigh the risk of excessive bleeding.<ref name=ATTaspirin2009>{{cite journal | vauthors = Baigent C, Blackwell L, Collins R, Emberson J, Godwin J, Peto R, Buring J, Hennekens C, Kearney P, Meade T, Patrono C, Roncaglioni MC, Zanchetti A | display-authors = 6 | title = Aspirin in the primary and secondary prevention of vascular disease: collaborative meta-analysis of individual participant data from randomised trials | journal = Lancet | volume = 373 | issue = 9678 | pages = 1849–60 | date = May 2009 | pmid = 19482214 | pmc = 2715005 | doi = 10.1016/S0140-6736(09)60503-1 }}</ref><ref>{{cite journal|display-authors=6|vauthors=Sutcliffe P, Connock M, Gurung T, Freeman K, Johnson S, Kandala NB, Grove A, Gurung B, Morrow S, Clarke A|date=September 2013|title=Aspirin for prophylactic use in the primary prevention of cardiovascular disease and cancer: a systematic review and overview of reviews|url=https://doi.org/10.3310%2Fhta17430|journal=Health Technology Assessment|volume=17|issue=43|pages=1–253|doi=10.3310/hta17430|pmc=4781046|pmid=24074752}}</ref> Nevertheless, many clinical practice guidelines continue to recommend aspirin for primary prevention,<ref>{{cite journal | vauthors = Matthys F, De Backer T, De Backer G, Stichele RV | title = Review of guidelines on primary prevention of cardiovascular disease with aspirin: how much evidence is needed to turn a tanker? | journal = European Journal of Preventive Cardiology | volume = 21 | issue = 3 | pages = 354–65 | date = March 2014 | pmid = 23610452 | doi = 10.1177/2047487312472077 | s2cid = 28350632 | doi-access = free }}</ref> and some researchers feel that those with very high cardiovascular risk but low risk of bleeding should continue to receive aspirin.<ref>{{cite journal | vauthors = Hodis HN, Mack WJ | title = Hormone replacement therapy and the association with coronary heart disease and overall mortality: clinical application of the timing hypothesis | journal = The Journal of Steroid Biochemistry and Molecular Biology | volume = 142 | pages = 68–75 | date = July 2014 | pmid = 23851166 | doi = 10.1016/j.jsbmb.2013.06.011 | s2cid = 30838065 }}</ref>

=== Secondary prevention ===
There is a large crossover between the lifestyle and activity recommendations to prevent a myocardial infarction, and those that may be adopted as secondary prevention after an initial myocardial infarct.<ref name=Reed2017 /> Recommendations include stopping smoking, a gradual return to exercise, eating a healthy diet, low in [[Chemistry:Saturated fat|saturated fat]] and low in [[Chemistry:Cholesterol|cholesterol]], drinking alcohol within recommended limits, exercising, and trying to achieve a healthy weight.<ref name=Reed2017 /><ref name=NICE172 /> Exercise is both safe and effective even if people have had stents or heart failure,<ref>{{cite journal | vauthors = Anderson L, Taylor RS | title = Cardiac rehabilitation for people with heart disease: an overview of Cochrane systematic reviews | journal = The Cochrane Database of Systematic Reviews | volume = 2021 | issue = 12 | pages = CD011273 | date = December 2014 | pmid = 25503364 | doi = 10.1002/14651858.CD011273.pub2 | pmc = 7087435 | hdl-access = free | hdl = 10871/19152 }}</ref> and is recommended to start gradually after 1–2 weeks.<ref name=Reed2017 /> Counselling should be provided relating to medications used, and for warning signs of depression.<ref name=Reed2017 /> Previous studies suggested a benefit from [[Chemistry:Omega-3 fatty acid|omega-3 fatty acid]] supplementation but this has not been confirmed.<ref name=NICE172 />

==== Medications ====
Following a heart attack, nitrates, when taken for two days, and [[Biology:ACE inhibitor|ACE-inhibitors]] decrease the risk of death.<ref>{{cite journal | vauthors = Perez MI, Musini VM, Wright JM | title = Effect of early treatment with anti-hypertensive drugs on short and long-term mortality in patients with an acute cardiovascular event | journal = The Cochrane Database of Systematic Reviews | issue = 4 | pages = CD006743 | date = October 2009 | pmid = 19821384 | doi = 10.1002/14651858.CD006743.pub2 }}</ref> Other medications include:

[[Chemistry:Aspirin|Aspirin]] is continued indefinitely, as well as another antiplatelet agent such as clopidogrel or ticagrelor ("dual antiplatelet therapy" or DAPT) for up to twelve months.<ref name=NICE172 /> If someone has another medical condition that requires anticoagulation (e.g. with [[Chemistry:Warfarin|warfarin]]) this may need to be adjusted based on risk of further cardiac events as well as bleeding risk.<ref name=NICE172 /> In those who have had a stent, more than 12 months of clopidogrel plus aspirin does not affect the risk of death.<ref>{{cite journal | vauthors = Elmariah S, Mauri L, Doros G, Galper BZ, O'Neill KE, Steg PG, Kereiakes DJ, Yeh RW | display-authors = 6 | title = Extended duration dual antiplatelet therapy and mortality: a systematic review and meta-analysis | journal = Lancet | volume = 385 | issue = 9970 | pages = 792–8 | date = February 2015 | pmid = 25467565 | pmc = 4386690 | doi = 10.1016/S0140-6736(14)62052-3 }}</ref>

[[Chemistry:Beta blocker|Beta blocker]] therapy such as [[Chemistry:Metoprolol|metoprolol]] or [[Chemistry:Carvedilol|carvedilol]] is recommended to be started within 24 hours, provided there is no acute heart failure or [[Medicine:Heart block|heart block]].<ref name=AHA2013 /><ref name=AHANSTEMI2014 /> The dose should be increased to the highest tolerated.<ref name=NICE172 /> Contrary to most guidelines, the use of beta blockers does not appear to affect the risk of death,<ref>{{cite journal | vauthors = Bangalore S, Makani H, Radford M, Thakur K, Toklu B, Katz SD, DiNicolantonio JJ, Devereaux PJ, Alexander KP, Wetterslev J, Messerli FH | display-authors = 6 | title = Clinical outcomes with β-blockers for myocardial infarction: a meta-analysis of randomized trials | journal = The American Journal of Medicine | volume = 127 | issue = 10 | pages = 939–953 | date = October 2014 | pmid = 24927909 | doi = 10.1016/j.amjmed.2014.05.032 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Safi S, Sethi NJ, Nielsen EE, Feinberg J, Jakobsen JC, Gluud C | title = Beta-blockers for suspected or diagnosed acute myocardial infarction | journal = The Cochrane Database of Systematic Reviews | volume = 12 | issue = 12 | pages = CD012484 | date = December 2019 | pmid = 31845756 | pmc = 6915833 | doi = 10.1002/14651858.CD012484.pub2 | collaboration = Cochrane Heart Group }}</ref> possibly because other treatments for MI have improved. When beta blocker medication is given within the first 24–72 hours of a STEMI no lives are saved.<!-- <ref name=BetaNNT2015 /> --> However, 1 in 200 people were prevented from a repeat heart attack, and another 1 in 200 from having an abnormal heart rhythm.<!-- <ref name=BetaNNT2015 /> --> Additionally, for 1 in 91 the medication causes a [[Medicine:Cardiogenic shock|temporary decrease in the heart's ability to pump blood]].<ref name=BetaNNT2015>{{cite web|title=Beta Blockers for Acute Heart Attack (Myocardial Infarction)| vauthors = Newman D |date=19 August 2010|url=http://www.thennt.com/nnt/beta-blockers-for-heart-attack/|website=TheNNT.com|access-date=11 December 2015|url-status=live|archive-url=https://web.archive.org/web/20151222092449/http://www.thennt.com/nnt/beta-blockers-for-heart-attack/|archive-date=22 December 2015}}</ref> 

[[Biology:ACE inhibitor|ACE inhibitor]] therapy should be started within 24 hours and continued indefinitely at the highest tolerated dose. This is provided there is no evidence of worsening [[Medicine:Kidney failure|kidney failure]], high potassium, low blood pressure, or known narrowing of the renal arteries.<ref name=Reed2017 /> Those who cannot tolerate ACE inhibitors may be treated with an angiotensin II receptor antagonist.<ref name=NICE172 />

[[Biology:Statin|Statin]] therapy has been shown to reduce mortality and subsequent cardiac events and should be commenced to lower LDL cholesterol. Other medications, such as [[Chemistry:Ezetimibe|ezetimibe]], may also be added with this goal in mind.<ref name=Reed2017 />

Aldosterone antagonists ([[Biology:Spironolactone|spironolactone]] or [[Chemistry:Eplerenone|eplerenone]]) may be used if there is evidence of left ventricular dysfunction after an MI, ideally after beginning treatment with an ACE inhibitor.<ref name=NICE172 /><ref name="pmid26891235">{{cite journal | vauthors = Le HH, El-Khatib C, Mombled M, Guitarian F, Al-Gobari M, Fall M, Janiaud P, Marchant I, Cucherat M, Bejan-Angoulvant T, Gueyffier F | display-authors = 6 | title = Impact of Aldosterone Antagonists on Sudden Cardiac Death Prevention in Heart Failure and Post-Myocardial Infarction Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials | journal = PLOS ONE | volume = 11 | issue = 2 | pages = e0145958 | date = 2016 | pmid = 26891235 | pmc = 4758660 | doi = 10.1371/journal.pone.0145958 | bibcode = 2016PLoSO..1145958L | doi-access = free }}</ref>

==== Other ====
A [[Medicine:Defibrillator|defibrillator]], an electric device connected to the heart and surgically inserted under the skin, may be recommended. This is particularly if there are any ongoing signs of heart failure, with a low left ventricular ejection fraction and a New York Heart Association grade II or III after 40 days of the infarction.<ref name=Reed2017 /> Defibrillators detect potentially fatal arrhythmia and deliver an electrical shock to the person to depolarize a critical mass of the heart muscle.<ref name="Hazinski2015">{{cite journal | vauthors = Hazinski MF, Nolan JP, Aickin R, Bhanji F, Billi JE, Callaway CW, Castren M, de Caen AR, Ferrer JM, Finn JC, Gent LM, Griffin RE, Iverson S, Lang E, Lim SH, Maconochie IK, Montgomery WH, Morley PT, Nadkarni VM, Neumar RW, Nikolaou NI, Perkins GD, Perlman JM, Singletary EM, Soar J, Travers AH, Welsford M, Wyllie J, Zideman DA | display-authors = 6 | title = Part 1: Executive Summary: 2015 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations | journal = Circulation | volume = 132 | issue = 16 Suppl 1 | pages = S2–39 | date = October 2015 | pmid = 26472854 | doi = 10.1161/CIR.0000000000000270 | type = Review | doi-access = free }}</ref>

== Management ==
{{Main|Biology:Management of acute coronary syndrome}}
A myocardial infarction requires immediate medical attention. Treatment aims to preserve as much heart muscle as possible, and to prevent further complications.<ref name=Harrisons2015 /> Treatment depends on whether the myocardial infarction is a STEMI or NSTEMI.<ref name=Reed2017 /> Treatment in general aims to unblock blood vessels, reduce blood clot enlargement, reduce ischemia, and modify risk factors with the aim of preventing future MIs.<ref name=Harrisons2015 /> In addition, the main treatment for myocardial infarctions with ECG evidence of ST elevation (STEMI) include thrombolysis or [[Medicine:Percutaneous coronary intervention|percutaneous coronary intervention]], although PCI is also ideally conducted within 1–3 days for NSTEMI.<ref name=Reed2017 /> In addition to clinical judgement, risk stratification may be used to guide treatment, such as with the TIMI and GRACE scoring systems.<ref name="Davidsons2010" /><ref name=Reed2017 /><ref>{{cite journal | vauthors = Hess EP, Agarwal D, Chandra S, Murad MH, Erwin PJ, Hollander JE, Montori VM, Stiell IG | display-authors = 6 | title = Diagnostic accuracy of the TIMI risk score in patients with chest pain in the emergency department: a meta-analysis | journal = CMAJ | volume = 182 | issue = 10 | pages = 1039–44 | date = July 2010 | pmid = 20530163 | pmc = 2900327 | doi = 10.1503/cmaj.092119 }}</ref>

=== Pain ===
The pain associated with myocardial infarction is often treated with [[Chemistry:Nitroglycerin (medication)|nitroglycerin]], a vasodilator, or [[Chemistry:Opioid|opioid]] medications such as [[Biology:Morphine|morphine]].<ref name=Harrisons2015 /> Nitroglycerin (given [[Medicine:Sublingual administration|under the tongue]] or [[Chemistry:Intravenous therapy|injected into a vein]]) may improve blood supply to the heart.<ref name=Harrisons2015 /> It is an important part of therapy for its pain relief effects, though there is no proven benefit to [[Medicine:Case fatality rate|mortality]].<ref name=Harrisons2015 /><ref>{{cite web| vauthors = Reeder G |title=Nitrates in the management of acute coronary syndrome|url=https://www.uptodate.com/contents/nitrates-in-the-management-of-acute-coronary-syndrome|website=www.uptodate.com|access-date=24 May 2017 |date=27 December 2016|url-status=live |archive-url= https://web.archive.org/web/20170728135423/https://www.uptodate.com/contents/nitrates-in-the-management-of-acute-coronary-syndrome |archive-date=28 July 2017}}</ref> Morphine or other opioid medications may also be used, and are effective for the pain associated with STEMI.<ref name=Harrisons2015 /> There is poor evidence that morphine shows any benefit to [[Outcome measure|overall outcomes]], and there is some evidence of potential harm.<ref>{{cite journal | vauthors = Yadlapati A, Gajjar M, Schimmel DR, Ricciardi MJ, Flaherty JD | title = Contemporary management of ST-segment elevation myocardial infarction | journal = Internal and Emergency Medicine | volume = 11 | issue = 8 | pages = 1107–1113 | date = December 2016 | pmid = 27714584 | doi = 10.1007/s11739-016-1550-3 | s2cid = 23759756 }}</ref><ref>{{cite journal | vauthors = McCarthy CP, Mullins KV, Sidhu SS, Schulman SP, McEvoy JW | title = The on- and off-target effects of morphine in acute coronary syndrome: A narrative review | journal = American Heart Journal | volume = 176 | pages = 114–21 | date = June 2016 | pmid = 27264228 | doi = 10.1016/j.ahj.2016.04.004 }}</ref>

=== Antithrombotics ===
[[Chemistry:Aspirin|Aspirin]], an antiplatelet drug, is given as a [[Medicine:Loading dose|loading dose]] to reduce the clot size and reduce further clotting in the affected artery.<ref name=Harrisons2015 /><ref name=Reed2017 /> It is known to decrease mortality associated with acute myocardial infarction by at least 50%.<ref name=Reed2017 /> P2Y12 inhibitors such as [[Chemistry:Clopidogrel|clopidogrel]], [[Chemistry:Prasugrel|prasugrel]] and [[Chemistry:Ticagrelor|ticagrelor]] are given concurrently, also as a [[Medicine:Loading dose|loading dose]], with the dose depending on whether further surgical management or fibrinolysis is planned.<ref name=Reed2017 /> Prasugrel and ticagrelor are recommended in European and American guidelines, as they are active more quickly and consistently than clopidogrel.<ref name=Reed2017 /> P2Y12 inhibitors are recommended in both NSTEMI and STEMI, including in PCI, with evidence also to suggest improved mortality.<ref name=Reed2017 /> [[Chemistry:Heparin|Heparin]]s, particularly in the unfractionated form, act at several points in the clotting cascade, help to prevent the enlargement of a clot, and are also given in myocardial infarction, owing to evidence suggesting improved mortality rates.<ref name=Reed2017 /> In very high-risk scenarios, inhibitors of the platelet glycoprotein α<sub>IIb</sub>β<sub>3a</sub> receptor such as [[Chemistry:Eptifibatide|eptifibatide]] or [[Chemistry:Tirofiban|tirofiban]] may be used.<ref name=Reed2017 />

There is varying evidence on the mortality benefits in NSTEMI. A 2014 review of P2Y12 inhibitors such as [[Chemistry:Clopidogrel|clopidogrel]] found they do not change the risk of death when given to people with a suspected NSTEMI prior to PCI,<ref name=BMJP2Y12>{{cite journal | vauthors = Bellemain-Appaix A, Kerneis M, O'Connor SA, Silvain J, Cucherat M, Beygui F, Barthélémy O, Collet JP, Jacq L, Bernasconi F, Montalescot G | display-authors = 6 | title = Reappraisal of thienopyridine pretreatment in patients with non-ST elevation acute coronary syndrome: a systematic review and meta-analysis | journal = BMJ | volume = 349 | pages = g6269 | date = October 2014 | pmid = 25954988 | pmc = 4208629 | doi = 10.1136/bmj.g6269 }}</ref> nor do heparins change the risk of death.<ref name=And2014 /> They do decrease the risk of having a further myocardial infarction.<ref name=Reed2017 /><ref name=And2014>{{cite journal | vauthors = Andrade-Castellanos CA, Colunga-Lozano LE, Delgado-Figueroa N, Magee K | title = Heparin versus placebo for non-ST elevation acute coronary syndromes | journal = The Cochrane Database of Systematic Reviews | volume = 6 | issue = 6 | pages = CD003462 | date = June 2014 | pmid = 24972265 | pmc = 6769062 | doi = 10.1002/14651858.CD003462.pub3 }}</ref>
[[File:Myocardial infarction.svg|thumb|Inserting a stent to widen the artery.]]

=== Angiogram ===
Primary [[Medicine:Percutaneous coronary intervention|percutaneous coronary intervention]] (PCI) is the treatment of choice for STEMI if it can be performed in a timely manner, ideally within 90–120 minutes of contact with a medical provider.<ref name=Reed2017 /><ref name=Bagai2014>{{cite journal | vauthors = Bagai A, Dangas GD, Stone GW, Granger CB | title = Reperfusion strategies in acute coronary syndromes | journal = Circulation Research | volume = 114 | issue = 12 | pages = 1918–28 | date = June 2014 | pmid = 24902975 | doi = 10.1161/CIRCRESAHA.114.302744 | doi-access = free }}</ref> Some recommend it is also done in NSTEMI within 1–3 days, particularly when considered high-risk.<ref name=Reed2017 /> A 2017 review, however, did not find a difference between early versus later PCI in NSTEMI.<ref>{{cite journal | vauthors = Jobs A, Mehta SR, Montalescot G, Vicaut E, Van't Hof AW, Badings EA, Neumann FJ, Kastrati A, Sciahbasi A, Reuter PG, Lapostolle F, Milosevic A, Stankovic G, Milasinovic D, Vonthein R, Desch S, Thiele H | display-authors = 6 | title = Optimal timing of an invasive strategy in patients with non-ST-elevation acute coronary syndrome: a meta-analysis of randomised trials | journal = Lancet | volume = 390 | issue = 10096 | pages = 737–746 | date = August 2017 | pmid = 28778541 | doi = 10.1016/S0140-6736(17)31490-3 | s2cid = 4489347 }}</ref>

PCI involves small probes, inserted through peripheral blood vessels such as the femoral artery or radial artery into the blood vessels of the heart. The probes are then used to identify and clear blockages using small balloons, which are dragged through the blocked segment, dragging away the clot, or the insertion of stents.<ref name=Harrisons2015 /><ref name=Reed2017 /> Coronary artery bypass grafting is only considered when the affected area of heart muscle is large, and PCI is unsuitable, for example with difficult cardiac anatomy.<ref>{{cite journal | vauthors = Wijns W, Kolh P, Danchin N, Di Mario C, Falk V, Folliguet T, Garg S, Huber K, James S, Knuuti J, Lopez-Sendon J, Marco J, Menicanti L, Ostojic M, Piepoli MF, Pirlet C, Pomar JL, Reifart N, Ribichini FL, Schalij MJ, Sergeant P, Serruys PW, Silber S, Sousa Uva M, Taggart D | display-authors = 6 | title = Guidelines on myocardial revascularization | journal = European Heart Journal | volume = 31 | issue = 20 | pages = 2501–55 | date = October 2010 | pmid = 20802248 | doi = 10.1093/eurheartj/ehq277 | doi-access = free }}</ref> After PCI, people are generally placed on [[Chemistry:Aspirin|aspirin]] indefinitely and on dual antiplatelet therapy (generally aspirin and [[Chemistry:Clopidogrel|clopidogrel]]) for at least a year.<ref name=AHA2013 /><ref name=Reed2017 /><ref>{{cite journal | vauthors = Dalal F, Dalal HM, Voukalis C, Gandhi MM | title = Management of patients after primary percutaneous coronary intervention for myocardial infarction | journal = BMJ | volume = 358 | pages = j3237 | date = July 2017 | pmid = 28729460 | doi = 10.1136/bmj.j3237 | s2cid = 46847680 }}</ref>

=== Fibrinolysis ===
If PCI cannot be performed within 90 to 120 minutes in STEMI then fibrinolysis, preferably within 30 minutes of arrival to hospital, is recommended.<ref name=Reed2017 /><ref>{{cite journal | vauthors = Lassen JF, Bøtker HE, Terkelsen CJ | title = Timely and optimal treatment of patients with STEMI | journal = Nature Reviews. Cardiology | volume = 10 | issue = 1 | pages = 41–8 | date = January 2013 | pmid = 23165072 | doi = 10.1038/nrcardio.2012.156 | series = 1 | s2cid = 21955018 }}</ref> If a person has had symptoms for 12 to 24 hours evidence for effectiveness of thrombolysis is less and if they have had symptoms for more than 24 hours it is not recommended.<ref>{{cite journal | vauthors = Neumar RW, Shuster M, Callaway CW, Gent LM, Atkins DL, Bhanji F, Brooks SC, de Caen AR, Donnino MW, Ferrer JM, Kleinman ME, Kronick SL, Lavonas EJ, Link MS, Mancini ME, Morrison LJ, O'Connor RE, Samson RA, Schexnayder SM, Singletary EM, Sinz EH, Travers AH, Wyckoff MH, Hazinski MF | display-authors = 6 | title = Part 1: Executive Summary: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 132 | issue = 18 Suppl 2 | pages = S315–67 | date = November 2015 | pmid = 26472989 | doi = 10.1161/cir.0000000000000252 | doi-access = free }}</ref> Thrombolysis involves the administration of medication that activates the enzymes that normally dissolve blood clots. These medications include [[Biology:Tissue plasminogen activator|tissue plasminogen activator]], reteplase, [[Biology:Streptokinase|streptokinase]], and tenecteplase.<ref name=Harrisons2015 /> Thrombolysis is not recommended in a number of situations, particularly when associated with a high risk of bleeding or the potential for problematic bleeding, such as active bleeding, past [[Medicine:Stroke|stroke]]s or bleeds into the brain, or severe [[Medicine:Hypertension|hypertension]]. Situations in which thrombolysis may be considered, but with caution, include recent surgery, use of anticoagulants, pregnancy, and proclivity to bleeding.<ref name=Harrisons2015 /> Major risks of thrombolysis are major bleeding and intracranial bleeding.<ref name=Harrisons2015 /> Pre-hospital thrombolysis reduces time to thrombolytic treatment, based on studies conducted in higher income countries; however, it is unclear whether this has an impact on mortality rates.<ref name="mccaul">{{cite journal | vauthors = McCaul M, Lourens A, Kredo T | title = Pre-hospital versus in-hospital thrombolysis for ST-elevation myocardial infarction | journal = The Cochrane Database of Systematic Reviews | volume = 9 | issue = 9 | pages = CD010191 | date = September 2014 | pmid = 25208209 | pmc = 6823254 | doi = 10.1002/14651858.CD010191.pub2 }}</ref>

=== Other ===
In the past, high flow oxygen was recommended for everyone with a possible myocardial infarction.<ref name=AHANSTEMI2014 /> More recently, no evidence was found for routine use in those with normal oxygen levels and there is potential harm from the intervention.<ref>{{cite journal | vauthors = Cabello JB, Burls A, Emparanza JI, Bayliss SE, Quinn T | title = Oxygen therapy for acute myocardial infarction | journal = The Cochrane Database of Systematic Reviews | volume = 2016 | pages = CD007160 | date = December 2016 | issue = 12 | pmid = 27991651 | pmc = 6463792 | doi = 10.1002/14651858.CD007160.pub4 }}</ref><ref>{{cite journal | vauthors = Hofmann R, James SK, Jernberg T, Lindahl B, Erlinge D, Witt N, Arefalk G, Frick M, Alfredsson J, Nilsson L, Ravn-Fischer A, Omerovic E, Kellerth T, Sparv D, Ekelund U, Linder R, Ekström M, Lauermann J, Haaga U, Pernow J, Östlund O, Herlitz J, Svensson L | display-authors = 6 | title = Oxygen Therapy in Suspected Acute Myocardial Infarction | journal = The New England Journal of Medicine | volume = 377 | issue = 13 | pages = 1240–1249 | date = September 2017 | pmid = 28844200 | doi = 10.1056/nejmoa1706222 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Abuzaid A, Fabrizio C, Felpel K, Al Ashry HS, Ranjan P, Elbadawi A, Mohamed AH, Barssoum K, Elgendy IY | display-authors = 6 | title = Oxygen Therapy in Patients with Acute Myocardial Infarction: A Systemic Review and Meta-Analysis | journal = The American Journal of Medicine | volume = 131 | issue = 6 | pages = 693–701 | date = June 2018 | pmid = 29355510 | doi = 10.1016/j.amjmed.2017.12.027 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Sepehrvand N, James SK, Stub D, Khoshnood A, Ezekowitz JA, Hofmann R | title = Effects of supplemental oxygen therapy in patients with suspected acute myocardial infarction: a meta-analysis of randomised clinical trials | journal = Heart | volume = 104 | issue = 20 | pages = 1691–1698 | date = October 2018 | pmid = 29599378 | doi = 10.1136/heartjnl-2018-313089 | s2cid = 4472549 }}</ref><ref>{{cite journal | vauthors = Singh A, Hussain S, Antony B | title = How Much Evidence Is Needed to Conclude against the Use of Oxygen Therapy in Acute Myocardial Infarction? | journal = Res Pract Thromb Haemost. | date = 2020 | volume = 4 | issue = Suppl 1 | url = https://abstracts.isth.org/abstract/how-much-evidence-is-needed-to-conclude-against-the-use-of-oxygen-therapy-in-acute-myocardial-infarction/ | access-date = 28 July 2020 }}</ref> Therefore, oxygen is currently only recommended if oxygen levels are found to be low or if someone is in respiratory distress.<ref name=Harrisons2015 /><ref name=AHANSTEMI2014 />

If despite thrombolysis there is significant [[Medicine:Cardiogenic shock|cardiogenic shock]], continued severe chest pain, or less than a 50% improvement in [[Medicine:ST elevation|ST elevation]] on the ECG recording after 90 minutes, then rescue PCI is indicated emergently.<ref name=Wang2011>{{cite book|vauthors=Ardehali R, Perez M, Wang P |title=A practical approach to cardiovascular medicine|publisher=Wiley-Blackwell|location=Chichester, West Sussex, UK|isbn=978-1-4443-9387-3|year=2011|page=57|url=https://books.google.com/books?id=LZsoHMN8lM4C&pg=PA57}}</ref><ref>{{cite book|veditors=Jindal SK |title=Textbook of pulmonary and critical care medicine|publisher=Jaypee Brothers Medical Publishers|location=New Delhi|isbn=978-93-5025-073-0|year=2011|page=1758|url=https://books.google.com/books?id=rAT1bdnDakAC&pg=PA1758}}</ref>

Those who have had [[Medicine:Cardiac arrest|cardiac arrest]] may benefit from [[Biology:Targeted temperature management|targeted temperature management]] with evaluation for implementation of hypothermia protocols. Furthermore, those with cardiac arrest, and ST elevation at any time, should usually have angiography.<ref name=AHA2013 /> Aldosterone antagonists appear to be useful in people who have had an STEMI and do not have heart failure.<ref>{{cite journal | vauthors = Dahal K, Hendrani A, Sharma SP, Singireddy S, Mina G, Reddy P, Dominic P, Modi K | display-authors = 6 | title = Aldosterone Antagonist Therapy and Mortality in Patients With ST-Segment Elevation Myocardial Infarction Without Heart Failure: A Systematic Review and Meta-analysis | journal = JAMA Internal Medicine | volume = 178 | issue = 7 | pages = 913–920 | date = July 2018 | pmid = 29799995 | pmc = 6145720 | doi = 10.1001/jamainternmed.2018.0850 }}</ref>

=== Rehabilitation and exercise ===
[[Medicine:Cardiopulmonary rehabilitation|Cardiac rehabilitation]] benefits many who have experienced myocardial infarction,<ref name=Reed2017 /> even if there has been substantial heart damage and resultant left ventricular failure. It should start soon after discharge from the hospital. The program may include lifestyle advice, exercise, social support, as well as recommendations about driving, flying, sports participation, stress management, and sexual intercourse.<ref name=NICE172>{{NICE|172|Secondary prevention in primary and secondary care for patients following a myocardial infarction|2013}}</ref> Returning to sexual activity after myocardial infarction is a major concern for most patients, and is an important area to be discussed in the provision of holistic care.<ref>{{cite journal | vauthors = Rahim L, Allana S, Steinke EE, Ali F, Khan AH | title = Level of knowledge among cardiac nurses regarding sexual counseling of post-MI patients in three tertiary care hospitals in Pakistan | journal = Heart & Lung | volume = 46 | issue = 6 | pages = 412–416 | date = November 2017 | pmid = 28988654 | doi = 10.1016/j.hrtlng.2017.09.002 | s2cid = 4277993 }}</ref><ref name="pmid20168196">{{cite journal | vauthors = Jaarsma T, Steinke EE, Gianotten WL | title = Sexual problems in cardiac patients: how to assess, when to refer | journal = The Journal of Cardiovascular Nursing | volume = 25 | issue = 2 | pages = 159–64 | date = 2010 | pmid = 20168196 | doi = 10.1097/JCN.0b013e3181c60e7c | s2cid = 25806176 }}</ref>

In the short-term, exercise-based cardiovascular rehabilitation programs may reduce the risk of a myocardial infarction, reduces a large number of hospitalizations from all causes, reduces hospital costs, improves health-related quality of life, and has a small effect on all-cause mortality.<ref>{{cite journal | vauthors = Dibben G, Faulkner J, Oldridge N, Rees K, Thompson DR, Zwisler AD, Taylor RS | title = Exercise-based cardiac rehabilitation for coronary heart disease | journal = The Cochrane Database of Systematic Reviews | volume = 2021 | issue = 11 | pages = CD001800 | date = November 2021 | pmid = 34741536 | pmc = 8571912 | doi = 10.1002/14651858.CD001800.pub4 }}</ref> Longer-term studies indicate that exercise-based cardiovascular rehabilitation programs may reduce cardiovascular mortality and myocardial infarction.

== Prognosis ==
The prognosis after myocardial infarction varies greatly depending on the extent and location of the affected heart muscle, and the development and management of complications.<ref name=Davidsons2010 /> Prognosis is worse with older age and social isolation.<ref name=Davidsons2010 /> Anterior infarcts, persistent ventricular tachycardia or fibrillation, development of [[Medicine:Heart block|heart block]]s, and left ventricular impairment are all associated with poorer prognosis.<ref name=Davidsons2010 /> Without treatment, about a quarter of those affected by MI die within minutes and about forty percent within the first month.<ref name=Davidsons2010 /> Morbidity and mortality from myocardial infarction has, however, improved over the years due to earlier and better treatment:<ref name=Harrisons2015B /> in those who have a STEMI in the United States, between 5 and 6&nbsp;percent die before leaving the hospital and 7 to 18&nbsp;percent die within a year.<ref name=AHA2013 />

It is unusual for babies to experience a myocardial infarction, but when they do, about half die.<ref name=":0">{{cite journal | vauthors = Papneja K, Chan AK, Mondal TK, Paes B | title = Myocardial Infarction in Neonates: A Review of an Entity with Significant Morbidity and Mortality | journal = Pediatric Cardiology | volume = 38 | issue = 3 | pages = 427–441 | date = March 2017 | pmid = 28238152 | doi = 10.1007/s00246-016-1556-7 | s2cid = 20779415 }}</ref> In the short-term, neonatal survivors seem to have a normal quality of life.<ref name=":0" />

=== Complications ===
{{Main|Biology:Myocardial infarction complications}}
Complications may occur immediately following the myocardial infarction or may take time to develop. [[Medicine:Heart arrhythmia|Disturbances of heart rhythms]], including [[Medicine:Atrial fibrillation|atrial fibrillation]], [[Medicine:Ventricular tachycardia|ventricular tachycardia]] and [[Medicine:Ventricular fibrillation|fibrillation]] and [[Medicine:Heart block|heart block]] can arise as a result of ischemia, cardiac scarring, and infarct location.<ref name=Davidsons2010 /><ref name=Reed2017 /> [[Medicine:Stroke|Stroke]] is also a risk, either as a result of clots transmitted from the heart during PCI, as a result of bleeding following anticoagulation, or as a result of disturbances in the heart's ability to pump effectively as a result of the infarction.<ref name=Reed2017 /> [[Medicine:Mitral regurgitation|Regurgitation of blood through the mitral valve]] is possible, particularly if the infarction causes dysfunction of the papillary muscle.<ref name=Reed2017 /> [[Medicine:Cardiogenic shock|Cardiogenic shock]] as a result of the heart being unable to adequately pump blood may develop, dependent on infarct size, and is most likely to occur within the days following an acute myocardial infarction. Cardiogenic shock is the largest cause of in-hospital mortality.<ref name=Harrisons2015B /><ref name=Reed2017 /> Rupture of the ventricular dividing wall or left ventricular wall may occur within the initial weeks.<ref name=Reed2017 /> Dressler's syndrome, a reaction following larger infarcts and a cause of [[Medicine:Pericarditis|pericarditis]] is also possible.<ref name=Reed2017 />

[[Medicine:Heart failure|Heart failure]] may develop as a long-term consequence, with an impaired ability of heart muscle to pump, scarring, and an increase in the size of the existing muscle. [[Medicine:Ventricular aneurysm|Aneurysm of the left ventricle myocardium]] develops in about 10% of MI and is itself a risk factor for heart failure, ventricular arrhythmia, and the development of [[Medicine:Embolism|clots]].<ref name=Davidsons2010 />

Risk factors for complications and death include age, [[Physics:Hemodynamics|hemodynamic]] parameters (such as [[Medicine:Heart failure|heart failure]], [[Medicine:Cardiac arrest|cardiac arrest]] on admission, systolic [[Physics:Blood pressure|blood pressure]], or [[Medicine:Killip class|Killip class]] of two or greater), ST-segment deviation, diabetes, serum [[Chemistry:Creatinine|creatinine]], peripheral vascular disease, and elevation of cardiac markers.<ref name="PEPA">{{cite journal | vauthors = López de Sá E, López-Sendón J, Anguera I, Bethencourt A, Bosch X | title = Prognostic value of clinical variables at presentation in patients with non-ST-segment elevation acute coronary syndromes: results of the Proyecto de Estudio del Pronóstico de la Angina (PEPA) | journal = Medicine | volume = 81 | issue = 6 | pages = 434–42 | date = November 2002 | pmid = 12441900 | doi = 10.1097/00005792-200211000-00004 | author6 = Proyecto de Estudio del Pronostico de la Angina (PEPA) Investigators | s2cid = 10268606 | doi-access = free | hdl = 20.500.13003/14561 | hdl-access = free }}</ref><ref name="GRACE">{{cite journal | vauthors = Fox KA, Dabbous OH, Goldberg RJ, Pieper KS, Eagle KA, Van de Werf F, Avezum A, Goodman SG, Flather MD, Anderson FA, Granger CB | display-authors = 6 | title = Prediction of risk of death and myocardial infarction in the six months after presentation with acute coronary syndrome: prospective multinational observational study (GRACE) | journal = BMJ | volume = 333 | issue = 7578 | pages = 1091 | date = November 2006 | pmid = 17032691 | pmc = 1661748 | doi = 10.1136/bmj.38985.646481.55 }}</ref><ref name="Weir-2006">{{cite journal | vauthors = Weir RA, McMurray JJ, Velazquez EJ | title = Epidemiology of heart failure and left ventricular systolic dysfunction after acute myocardial infarction: prevalence, clinical characteristics, and prognostic importance | journal = The American Journal of Cardiology | volume = 97 | issue = 10A | pages = 13F–25F | date = May 2006 | pmid = 16698331 | doi = 10.1016/j.amjcard.2006.03.005 }}</ref>

== Epidemiology ==
Myocardial infarction is a common presentation of [[Medicine:Coronary artery disease|coronary artery disease]]. The [[Organization:World Health Organization|World Health Organization]] estimated in 2004, that 12.2% of worldwide deaths were from ischemic heart disease;<ref name="WHO-2004">{{cite book |author=World Health Organization |title=The Global Burden of Disease: 2004 Update |publisher=World Health Organization |location=Geneva |year=2008 |isbn=978-92-4-156371-0 }}</ref> with it being the leading cause of death in high- or middle-income countries and second only to [[Medicine:Lower respiratory tract infection|lower respiratory infections]] in [[Finance:Developing country|lower-income countries]].<ref name="WHO-2004" /> Worldwide, more than 3 million people have STEMIs and 4 million have NSTEMIs a year.<ref name="Lancet08" /> STEMIs occur about twice as often in men as women.<ref name=AHA2013 />

Rates of death from ischemic heart disease (IHD) have slowed or declined in most high-income countries, although cardiovascular disease still accounted for one in three of all deaths in the US in 2008.<ref>{{cite journal | vauthors = Roger VL, Go AS, Lloyd-Jones DM, Benjamin EJ, Berry JD, Borden WB, Bravata DM, Dai S, Ford ES, Fox CS, Fullerton HJ, Gillespie C, Hailpern SM, Heit JA, Howard VJ, Kissela BM, Kittner SJ, Lackland DT, Lichtman JH, Lisabeth LD, Makuc DM, Marcus GM, Marelli A, Matchar DB, Moy CS, Mozaffarian D, Mussolino ME, Nichol G, Paynter NP, Soliman EZ, Sorlie PD, Sotoodehnia N, Turan TN, Virani SS, Wong ND, Woo D, Turner MB | display-authors = 6 | collaboration =  American Heart Association Statistics Committee and Stroke Statistics Subcommittee | title = Executive summary: heart disease and stroke statistics--2012 update: a report from the American Heart Association | journal = Circulation | volume = 125 | issue = 1 | pages = 188–97 | date = January 2012 | pmid = 22215894 | doi = 10.1161/CIR.0b013e3182456d46 | doi-access = free }}</ref> For example, rates of death from cardiovascular disease have decreased almost a third between 2001 and 2011 in the United States.<ref>{{cite journal | vauthors = Mozaffarian D, Benjamin EJ, Go AS, Arnett DK, Blaha MJ, Cushman M, de Ferranti S, Després JP, Fullerton HJ, Howard VJ, Huffman MD, Judd SE, Kissela BM, Lackland DT, Lichtman JH, Lisabeth LD, Liu S, Mackey RH, Matchar DB, McGuire DK, Mohler ER, Moy CS, Muntner P, Mussolino ME, Nasir K, Neumar RW, Nichol G, Palaniappan L, Pandey DK, Reeves MJ, Rodriguez CJ, Sorlie PD, Stein J, Towfighi A, Turan TN, Virani SS, Willey JZ, Woo D, Yeh RW, Turner MB | display-authors = 6 | title = Heart disease and stroke statistics--2015 update: a report from the American Heart Association | journal = Circulation | volume = 131 | issue = 4 | pages = e29–322 | date = January 2015 | pmid = 25520374 | doi = 10.1161/cir.0000000000000152 | quote = From 2001 to 2011, death rates attributable to CVD declined 30.8%. | doi-access = free }}</ref>

In contrast, IHD is becoming a more common cause of death in the developing world. For example, in {{wipe|India}}, IHD had become the leading cause of death by 2004, accounting for 1.46 million deaths (14% of total deaths) and deaths due to IHD were expected to double during 1985–2015.<ref>{{cite journal | vauthors = Gupta R, Joshi P, Mohan V, Reddy KS, Yusuf S | title = Epidemiology and causation of coronary heart disease and stroke in India | journal = Heart | volume = 94 | issue = 1 | pages = 16–26 | date = January 2008 | pmid = 18083949 | doi = 10.1136/hrt.2007.132951 | s2cid = 27117207 }}</ref> Globally, disability adjusted life years (DALYs) lost to ischemic heart disease are predicted to account for 5.5% of total DALYs in 2030, making it the second-most-important cause of disability (after unipolar depressive disorder), as well as the leading cause of death by this date.<ref name="WHO-2004" />

== Social determinants of health ==
Social determinants such as neighborhood disadvantage, immigration status, lack of [[Social:Social support|social support]], [[Social:Social isolation|social isolation]], and access to [[Medicine:Health care|health services]] play an important role in myocardial infarction risk and survival.<ref>{{cite journal | vauthors = Coady SA, Johnson NJ, Hakes JK, Sorlie PD | title = Individual education, area income, and mortality and recurrence of myocardial infarction in a Medicare cohort: the National Longitudinal Mortality Study | journal = BMC Public Health | volume = 14 | issue = 1 | pages = 705 | date = July 2014 | pmid = 25011538 | doi = 10.1186/1471-2458-14-705 | pmc = 4227052 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Salomaa V, Miettinen H, Niemelä M, Ketonen M, Mähönen M, Immonen-Räihä P, Lehto S, Vuorenmaa T, Koskinen S, Palomäki P, Mustaniemi H, Kaarsalo E, Arstila M, Torppa J, Kuulasmaa K, Puska P, Pyörälä K, Tuomilehto J | display-authors = 6 | title = Relation of socioeconomic position to the case fatality, prognosis and treatment of myocardial infarction events; the FINMONICA MI Register Study | journal = Journal of Epidemiology and Community Health | volume = 55 | issue = 7 | pages = 475–82 | date = July 2001 | pmid = 11413176 | doi = 10.1136/jech.55.7.475 | pmc = 1731938 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Bucholz EM, Ma S, Normand SL, Krumholz HM | title = Race, Socioeconomic Status, and Life Expectancy After Acute Myocardial Infarction | journal = Circulation | volume = 132 | issue = 14 | pages = 1338–46 | date = October 2015 | pmid = 26369354 | doi = 10.1161/circulationaha.115.017009 | pmc = 5097251 }}</ref><ref>{{cite journal | vauthors = Kilpi F, Silventoinen K, Konttinen H, Martikainen P | title = Disentangling the relative importance of different socioeconomic resources for myocardial infarction incidence and survival: a longitudinal study of over 300,000 Finnish adults | journal = European Journal of Public Health | volume = 26 | issue = 2 | pages = 260–6 | date = April 2016 | pmid = 26585783 | doi = 10.1093/eurpub/ckv202 | doi-access = free }}</ref> Studies have shown that low [[Social:Socioeconomic status|socioeconomic status]] is associated with an increased risk of poorer survival. There are well-documented disparities in myocardial infarction survival by [[Social:Socioeconomic status|socioeconomic status]], race, education, and census-tract-level poverty.<ref>{{cite journal | vauthors = Rosvall M, Gerward S, Engström G, Hedblad B | title = Income and short-term case fatality after myocardial infarction in the whole middle-aged population of Malmö, Sweden | journal = European Journal of Public Health | volume = 18 | issue = 5 | pages = 533–8 | date = October 2008 | pmid = 18621776 | doi = 10.1093/eurpub/ckn059 | doi-access = free }}</ref>

Race: In the U.S. African Americans have a greater burden of myocardial infarction and other cardiovascular events. On a population level, there is a higher overall [[Prevalence|prevalence]] of risk factors that are unrecognized and therefore not treated, which places these individuals at a greater likelihood of experiencing adverse outcomes and therefore potentially higher morbidity and [[Mortality rate|mortality]].<ref>{{cite journal | vauthors = Graham G | title = Disparities in cardiovascular disease risk in the United States | journal = Current Cardiology Reviews | volume = 11 | issue = 3 | pages = 238–45 | date = 2015-05-14 | pmid = 25418513 | pmc = 4558355 | doi = 10.2174/1573403X11666141122220003 }}</ref> Similarly, South Asians (including South Asians that have migrated to other countries around the world) experience higher rates of acute myocardial infarctions at younger ages, which can be largely explained by a higher prevalence of risk factors at younger ages.<ref>{{cite journal| last = Joshi | first = Prashant | date = 2007-01-17 | title = Risk Factors for Early Myocardial Infarction in South Asians Compared With Individuals in Other Countries | url = https://jamanetwork.com/journals/jama/article-abstract/205159 | access-date = 2023-11-16 | journal = JAMA | volume = 297 | issue = 3 | pages = 286–294 | doi = 10.1001/jama.297.3.286 | pmid = 17227980 }}</ref>

Socioeconomic status: Among individuals who live in the low-[[Social:Socioeconomic status|socioeconomic]] (SES) areas, which is close to 25% of the US population, myocardial infarctions (MIs) occurred twice as often compared with people who lived in higher SES areas.<ref>{{cite journal | vauthors = Hamad R, Penko J, Kazi DS, Coxson P, Guzman D, Wei PC, Mason A, Wang EA, Goldman L, Fiscella K, Bibbins-Domingo K | display-authors = 6 | title = Association of Low Socioeconomic Status With Premature Coronary Heart Disease in US Adults | journal = JAMA Cardiology | volume = 5 | issue = 8 | pages = 899–908 | date = May 2020 | pmid = 32459344 | pmc = 7254448 | doi = 10.1001/jamacardio.2020.1458 }}</ref>

Immigration status: In 2018 many lawfully present immigrants who are eligible for coverage remain uninsured because immigrant families face a range of enrollment barriers, including fear, confusion about eligibility policies, difficulty navigating the enrollment process, and [[Social:Language|language]] and [[Philosophy:Literacy|literacy]] challenges. Uninsured undocumented immigrants are ineligible for coverage options due to their immigration status.<ref>{{cite web |date=2020-03-18|title=Health Coverage of Immigrants|url=https://www.kff.org/racial-equity-and-health-policy/fact-sheet/health-coverage-of-immigrants/|access-date=2021-04-09|website=KFF|language=en-US}}</ref>

Health care access: Lack of health insurance and financial concerns about accessing care were associated with delays in seeking emergency care for acute myocardial infarction which can have significant, adverse consequences on patient outcomes.<ref>{{cite journal | vauthors = Smolderen KG, Spertus JA, Nallamothu BK, Krumholz HM, Tang F, Ross JS, Ting HH, Alexander KP, Rathore SS, Chan PS | display-authors = 6 | title = Health care insurance, financial concerns in accessing care, and delays to hospital presentation in acute myocardial infarction | journal = JAMA | volume = 303 | issue = 14 | pages = 1392–400 | date = April 2010 | pmid = 20388895 | pmc = 3020978 | doi = 10.1001/jama.2010.409 }}</ref>

Education: Researchers found that compared to people with graduate degrees, those with lower educational attainment appeared to have a higher [[Risk|risk]] of heart attack, dying from a cardiovascular event, and overall death.<ref>{{cite journal | vauthors = Kelli HM, Mehta A, Tahhan AS, Liu C, Kim JH, Dong TA, Dhindsa DS, Ghazzal B, Choudhary MK, Sandesara PB, Hayek SS, Topel ML, Alkhoder AA, Martini MA, Sidoti A, Ko YA, Lewis TT, Vaccarino V, Sperling LS, Quyyumi AA | display-authors = 6 | title = Low Educational Attainment is a Predictor of Adverse Outcomes in Patients With Coronary Artery Disease | journal = Journal of the American Heart Association | volume = 8 | issue = 17 | pages = e013165 | date = September 2019 | pmid = 31476920 | pmc = 6755831 | doi = 10.1161/JAHA.119.013165 }}</ref>

== Society and culture ==
Depictions of heart attacks in popular media often include collapsing or loss of consciousness which are not common symptoms; these depictions contribute to widespread misunderstanding about the symptoms of myocardial infarctions, which in turn contributes to people not getting care when they should.<ref>{{cite journal | vauthors = Perry K, Petrie KJ, Ellis CJ, Horne R, Moss-Morris R | title = Symptom expectations and delay in acute myocardial infarction patients | journal = Heart | volume = 86 | issue = 1 | pages = 91–3 | date = July 2001 | pmid = 11410572 | pmc = 1729795 | doi = 10.1136/heart.86.1.91 }}</ref>

=== Legal implications ===
At common law, in general, a myocardial infarction is a [[Disease|disease]] but may sometimes be an [[Biology:Injury|injury]]. This can create coverage issues in the administration of no-fault insurance schemes such as [[Workers' compensation|workers' compensation]]. In general, a heart attack is not covered;<ref name=prairieview>[http://www.pvamu.edu/pages/2026.asp Workers' Compensation FAQ] {{webarchive|url=https://web.archive.org/web/20070711235600/http://www.pvamu.edu/pages/2026.asp |date=2007-07-11 }}. Prairie View A&M University. Retrieved November 22, 2006.</ref> however, it may be a work-related injury if it results, for example, from unusual emotional stress or unusual exertion.<ref name=biia>[http://www.biia.wa.gov/significantdecisions/contents.htm SIGNIFICANT DECISIONS Subject Index] {{webarchive|url=https://web.archive.org/web/20061206115257/http://www.biia.wa.gov/SignificantDecisions/contents.htm |date=2006-12-06 }}. Board of Industrial Insurance Appeals. Retrieved November 22, 2006.</ref> In addition, in some jurisdictions, heart attacks had by persons in particular occupations such as [[Social:Police officer|police officer]]s may be classified as line-of-duty injuries by statute or policy. In some countries or states, a person having had an MI may be prevented from participating in activity that puts other people's lives at risk, for example driving a car or flying an airplane.<ref name="NovaScotia-DrivingRegulations">{{cite web | title=Classification of Drivers' Licenses Regulations | publisher=Nova Scotia Registry of Regulations | date=May 24, 2000 | url=http://www.gov.ns.ca/just/regulations/regs/mvclasdl.htm | access-date=April 22, 2007 | url-status=live | archive-url=https://web.archive.org/web/20070420191108/http://www.gov.ns.ca/just/regulations/regs/mvclasdl.htm | archive-date=April 20, 2007 }}</ref>

== References ==
{{Reflist}}

=== Sources ===
{{refbegin}}
* {{cite book| vauthors = Allison TG, Murphy JG |chapter=Stress Test Selection|pages=196–202| veditors = Murphy JG, Lloyd MA, Brady PA, Olsen LJ, Shields RC |title=Mayo Clinic Cardiology: Concise Textbook|url=https://books.google.com/books?id=WSCRAAAAQBAJ|date=6 December 2012|publisher=OUP US|isbn=978-0-19-991571-2}}
* {{cite book| vauthors = Blumenthal RS, Margolis S |title=Heart Attack Prevention 2007|url=https://books.google.com/books?id=mM3l59uTj04C&pg=PA10|year=2007|publisher=Johns Hopkins Health|isbn=978-1-933087-47-4}}
* {{cite book| vauthors = Dwight J |chapter=Chest pain, breathlessness, fatigue|pages=39–47| veditors = Warrell D, Cox T, Firth J, Dwight J |title=Oxford Textbook of Medicine: Cardiovascular Disorders|url=https://books.google.com/books?id=YqJHDAAAQBAJ|date=16 June 2016|publisher=Oxford University Press|isbn=978-0-19-871702-7}}
* {{cite book| vauthors = Gaziano TA, Gaziano JM |chapter= Global Evolving Epidemiology, Natural History, and Treatment Trends of Myocardial Infarction|pages= 11–21 | veditors = Morrow DA | title=Myocardial Infarction: A Companion to Braunwald's Heart Disease|url=https://books.google.com/books?id=0TzrjwEACAAJ|date=15 September 2016|publisher=Elsevier|isbn=978-0-323-35943-6}}
* {{cite book| vauthors = Morrow DA, Bohula EA |chapter = Heart Failure and Cardiogenic Shock After Myocardial Infarction|pages=295–313 | veditors = Morrow DA | title=Myocardial Infarction: A Companion to Braunwald's Heart Disease|url=https://books.google.com/books?id=0TzrjwEACAAJ|date=15 September 2016|publisher=Elsevier|isbn=978-0-323-35943-6}}
* {{cite book| vauthors = Morrow DA, Braunwald E |chapter = Classification and Diagnosis of Acute Coronary Syndromes|pages=1–10 | veditors = Morrow DA | title=Myocardial Infarction: A Companion to Braunwald's Heart Disease|url=https://books.google.com/books?id=0TzrjwEACAAJ|date=15 September 2016|publisher=Elsevier|isbn=978-0-323-35943-6}}
* {{cite book| vauthors = Morrow DA |chapter=Clinical Approach to Suspected Acute Myocardial Infarction|pages= 55–65 | veditors = Morrow DA | title=Myocardial Infarction: A Companion to Braunwald's Heart Disease|url=https://books.google.com/books?id=0TzrjwEACAAJ|date=15 September 2016|publisher=Elsevier|isbn=978-0-323-35943-6}}
{{refend}}

== Further reading ==
{{refbegin}}
* {{cite journal | vauthors = Levine GN, Bates ER, Blankenship JC, Bailey SR, Bittl JA, Cercek B, Chambers CE, Ellis SG, Guyton RA, Hollenberg SM, Khot UN, Lange RA, Mauri L, Mehran R, Moussa ID, Mukherjee D, Ting HH, O'Gara PT, Kushner FG, Ascheim DD, Brindis RG, Casey DE, Chung MK, de Lemos JA, Diercks DB, Fang JC, Franklin BA, Granger CB, Krumholz HM, Linderbaum JA, Morrow DA, Newby LK, Ornato JP, Ou N, Radford MJ, Tamis-Holland JE, Tommaso CL, Tracy CM, Woo YJ, Zhao DX | display-authors = 6 | title = 2015 ACC/AHA/SCAI Focused Update on Primary Percutaneous Coronary Intervention for Patients With ST-Elevation Myocardial Infarction: An Update of the 2011 ACCF/AHA/SCAI Guideline for Percutaneous Coronary Intervention and the 2013 ACCF/AHA Guideline for the Management of ST-Elevation Myocardial Infarction: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Society for Cardiovascular Angiography and Interventions | journal = Circulation | volume = 133 | issue = 11 | pages = 1135–47 | date = March 2016 | pmid = 26490017 | doi = 10.1161/CIR.0000000000000336 | doi-access = free }}
* {{cite journal | vauthors=((Min Cho, S.)), ((et al.)) | year=2021 | title= Machine learning compared with conventional statistical models for predicting myocardial infarction readmission and mortality: a systematic review | journal=Canadian Journal of Cardiology | volume=37 | issue=8 | pages=1207–1214 | publisher=Elsevier | doi=10.1016/j.cjca.2021.02.020 | pmid=33677098 |doi-access=| s2cid=232141652 }}
{{refend}}

== External links ==
{{Medical condition classification and resources
| DiseasesDB     = 8664
| ICD10          = {{ICD10|I|21||i|20}}-{{ICD10|I|22||i|20}}
| ICD9           = {{ICD9|410}}
| MedlinePlus    = 000195
| eMedicineSubj  = med
| eMedicineTopic = 1567
| eMedicine_mult = {{eMedicine2|emerg|327}} {{eMedicine2|ped|2520}}
| MeshID         = D009203
}}
* {{curlie|Health/Conditions_and_Diseases/Cardiovascular_Disorders/Heart_Disease}}
* [http://www.americanheart.org/heartattack American Heart Association's Heart Attack web site] — Information and resources for preventing, recognizing, and treating a heart attack.
* TIMI Score for [http://www.mdcalc.com/timi-risk-score-for-uanstemi/ UA/NSTEMI] {{Webarchive|url=https://web.archive.org/web/20161105220551/http://www.mdcalc.com/timi-risk-score-for-uanstemi/ |date=2016-11-05 }} and [http://www.mdcalc.com/timi-risk-score-for-stemi/ STEMI] {{Webarchive|url=https://web.archive.org/web/20090319073410/http://www.mdcalc.com/timi-risk-score-for-stemi |date=2009-03-19 }}
* [http://www.mdcalc.com/heart-score-for-major-cardiac-events/ HEART Score for Major Cardiac Events] {{Webarchive|url=https://web.archive.org/web/20161028004807/http://www.mdcalc.com/heart-score-for-major-cardiac-events/ |date=2016-10-28 }}
* {{cite web | url = https://medlineplus.gov/heartattack.html | publisher = U.S. National Library of Medicine | work = MedlinePlus | title = Heart Attack }}

{{Circulatory system pathology}}
{{Hemodynamics}}


[[Category:Aging-associated diseases]]
[[Category:Medical emergencies]]
[[Category:Wikipedia medicine articles ready to translate]]
[[Category:Acute pain]]

{{Sourceattribution|Myocardial infarction}}