Heart attack (myocardial infarction)
Also called: MI, STEMI, NSTEMI, Acute coronary syndrome
This can be a medical emergency. Call emergency services immediately for chest pain lasting more than a few minutes. Do not drive yourself to hospital.
A coronary artery is suddenly blocked, usually by a clot on a ruptured plaque, and the heart muscle it supplies starts to die. Every minute counts: rapid reopening of the artery saves muscle and lives.
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Around 800,000 heart attacks a year in the USA alone; the most common cause of sudden death.
What happens in the body
A clot forms on a cracked atherosclerotic plaque. Complete blockage produces ST-elevation MI (STEMI); partial or intermittent blockage produces NSTEMI or unstable angina. Muscle begins to die within 20–40 minutes.
Causes
- Plaque rupture with clot (most cases)
- Coronary spasm (e.g. cocaine)
- Spontaneous coronary artery dissection (young women, pregnancy)
- Supply–demand mismatch: severe anaemia, very fast heart rhythm, low blood pressure
Risk factors
- Same as coronary artery disease: smoking, high cholesterol, hypertension, diabetes, obesity, family history, age
Symptoms
- Crushing, squeezing or heavy central chest pain lasting over 15 minutes
- Pain in the left arm, jaw, neck, back or upper abdomen
- Sweating, nausea, vomiting
- Breathlessness
- Light-headedness or collapse
- Women, older people and people with diabetes may have only breathlessness, fatigue or indigestion-like discomfort
Diagnosis — tests and examinations
- 12-lead ECG within 10 minutes of arrival
- High-sensitivity troponin blood test (repeated)
- Echocardiogram to assess heart pumping
- Emergency coronary angiography
Treatment
Medicines and medical treatment
- Aspirin 300 mg chewed immediately (unless allergic)
- Second antiplatelet (ticagrelor, prasugrel or clopidogrel)
- Anticoagulation (heparin)
- Oxygen only if levels are low; pain relief
- Afterwards: lifelong aspirin, high-intensity statin, beta-blocker, ACE inhibitor; dual antiplatelet therapy usually for 12 months
Operations and procedures
- Primary PCI (angioplasty and stent) — ideally within 90–120 minutes for STEMI
- Clot-busting drugs (thrombolysis) if PCI is not available in time
- Bypass surgery in selected cases
- Implantable defibrillator if heart function stays severely reduced
Self-care, home remedies and lifestyle
- Cardiac rehabilitation programme
- Stop smoking
- Heart-healthy diet and gradual return to exercise
- Take all prescribed medicines — stopping antiplatelets early risks stent clotting
Possible complications
- Ventricular fibrillation and sudden death
- Heart failure and cardiogenic shock
- Mitral regurgitation or rupture of the heart wall (rare)
- Pericarditis
- Left ventricular clot and stroke
- Depression
Prevention
- Control of all cardiovascular risk factors
- Statins and aspirin for people with established heart disease
- Knowing the warning signs and calling for help early
Outlook
Hospital survival exceeds 90% with modern treatment; long-term outlook depends on how much muscle was damaged and how well risk factors are controlled afterwards.
When to see a doctor
Call emergency services immediately for chest pain lasting more than a few minutes. Do not drive yourself to hospital.
Sources and further reading
These sources cover this condition. They have not been checked against every statement on this page.
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