Myocardial infarction

"Heart attack" redirects here. For other uses, see Heart attack (disambiguation).
Not to be confused with cardiac arrest, heart failure, or heart block.

Myocardial infarction
Other namesAcute myocardial infarction (AMI), heart attack
A myocardial infarction occurs when an atherosclerotic plaque slowly builds up in the inner lining of a coronary artery and then suddenly ruptures, causing catastrophic thrombus formation, totally occluding the artery and preventing blood flow downstream to the heart muscle.
SpecialtyCardiology, emergency medicine
SymptomsChest pain, shortness of breath, nausea/vomiting, dizziness or lightheadedness, cold sweat, feeling tired; arm, neck, back, jaw, or stomach pain,[1][2] decreased level or total loss of consciousness
ComplicationsHeart failure, irregular heartbeat, cardiogenic shock, coma, cardiac arrest[3][4]
CausesAngina or coronary artery disease usually[3]
Risk factorsHigh blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol[5][6]
Diagnostic methodElectrocardiograms (ECGs), blood tests, coronary angiography[7]
TreatmentPercutaneous coronary intervention, thrombolysis[8]
MedicationAspirin, nitroglycerin, heparin[8][9]
PrognosisSTEMI 10% risk of death (developed world)[8]
Frequency15.9 million (2015)[10]

A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle.[1] The most common symptom is retrosternal chest pain or discomfort that classically radiates to the left shoulder, arm, or jaw.[1] The pain may occasionally feel like heartburn.[1] This is the dangerous type of Acute coronary syndrome.

Other symptoms may include shortness of breath, nausea, feeling faint, a cold sweat, feeling tired, and decreased level of consciousness.[1] About 30% of people have atypical symptoms.[8] Women more often present without chest pain and instead have neck pain, arm pain or feel tired.[11] Among those over 75 years old, about 5% have had an MI with little or no history of symptoms.[12] An MI may cause heart failure, an irregular heartbeat, cardiogenic shock or cardiac arrest.[3][4]

Most MIs occur due to coronary artery disease.[3] Risk factors include high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol, poor diet, and excessive alcohol intake.[5][6] The complete blockage of a coronary artery caused by a rupture of an atherosclerotic plaque is usually the underlying mechanism of an MI.[3] MIs are less commonly caused by coronary artery spasms, which may be due to cocaine, significant emotional stress (often known as Takotsubo syndrome or broken heart syndrome) and extreme cold, among others.[13][14] Many tests are helpful to help with diagnosis, including electrocardiograms (ECGs), blood tests and coronary angiography.[7] An ECG, which is a recording of the heart's electrical activity, may confirm an ST elevation MI (STEMI), if ST elevation is present.[8][15] Commonly used blood tests include troponin and less often creatine kinase MB.[7]

Treatment of an MI is time-critical.[16] Aspirin is an appropriate immediate treatment for a suspected MI.[9] Nitroglycerin or opioids may be used to help with chest pain; however, they do not improve overall outcomes.[8][9] Supplemental oxygen is recommended in those with low oxygen levels or shortness of breath.[9] In a STEMI, treatments attempt to restore blood flow to the heart and include percutaneous coronary intervention (PCI), where the arteries are pushed open and may be stented, or thrombolysis, where the blockage is removed using medications.[8] People who have a non-ST elevation myocardial infarction (NSTEMI) are often managed with the blood thinner heparin, with the additional use of PCI in those at high risk.[9] In people with blockages of multiple coronary arteries and diabetes, coronary artery bypass surgery (CABG) may be recommended rather than angioplasty.[17] After an MI, lifestyle modifications, along with long-term treatment with aspirin, beta blockers and statins, are typically recommended.[8]

Worldwide, about 15.9 million myocardial infarctions occurred in 2015.[10] More than 3 million people had an ST elevation MI, and more than 4 million had an NSTEMI.[18] STEMIs occur about twice as often in men as women.[19] About one million people have an MI each year in the United States.[3] In the developed world, the risk of death in those who have had a STEMI is about 10%.[8] Rates of MI for a given age have decreased globally between 1990 and 2010.[20] 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.[21]

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  17. ^ Hamm CW, Bassand JP, Agewall S, Bax J, Boersma E, Bueno H, et al. (December 2011). "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)". European Heart Journal. 32 (23): 2999–3054. doi:10.1093/eurheartj/ehr236. PMID 21873419.
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