Heart attack (myocardial infarction)
Also known as: heart attack, MI, STEMI, NSTEMI
Death of heart muscle because a coronary artery is suddenly blocked, usually by a clot forming on a ruptured plaque.
Overview
Every minute of blockage kills more muscle, so a heart attack is treated as a race to reopen the artery. Survival and the amount of muscle saved depend on how quickly the person calls for help and reaches a hospital able to perform emergency angioplasty.
Causes
- Rupture of an atherosclerotic plaque with clot formation
- Less often: coronary spasm, spontaneous artery dissection, severe anaemia or oxygen lack with a fixed narrowing
Risk factors
- Same as coronary artery disease: smoking, cholesterol, blood pressure, diabetes, family history, age
- Cocaine and amphetamine use
- Extreme physical or emotional stress
Symptoms
What a clinician may find
- Pale, sweaty, distressed
- Fast or slow pulse, low or high blood pressure
- Crackles in the lungs if the heart is failing
Complications
- Cardiac arrest from ventricular fibrillation
- Heart failure
- Rupture of the heart wall or a papillary muscle
- Arrhythmias and heart block
- Pericarditis
Diagnosis
An ECG within ten minutes of arrival shows ST elevation (STEMI) when a large artery is fully blocked; troponin in the blood rises over hours and confirms muscle damage in other cases. Echocardiography shows which wall has stopped moving.
Treatment
Aspirin immediately, then emergency angioplasty with a stent to reopen the artery (or clot-dissolving drugs if angioplasty is not reachable within about two hours). Afterwards: a second antiplatelet drug, a statin, a beta blocker and an ACE inhibitor, cardiac rehabilitation and risk factor control.
Prevention
The measures that prevent coronary artery disease; after a first attack, lifelong medication and rehabilitation halve the risk of another.
When to seek care
Call emergency services immediately for crushing chest pain, pain spreading to the arm or jaw, or chest discomfort with sweating, breathlessness or nausea. Do not drive yourself.