Overview
A heart attack (myocardial infarction) occurs when the blood supply to part of the heart muscle is suddenly blocked, usually by a blood clot forming on top of a ruptured cholesterol plaque in a coronary artery. Heart muscle begins to die within minutes. Every minute without treatment increases permanent damage.
How common is it?
The British Heart Foundation reports around 100,000 hospital admissions for heart attacks each year in the UK. Admissions are not the same as the number of individual people affected.
Causes and risk factors
Atherosclerotic plaques (cholesterol deposits) build up in coronary artery walls over decades. When a plaque ruptures, a blood clot forms rapidly, blocking the artery and cutting off blood supply to heart muscle downstream.
Common risk factors
- Coronary artery disease
- High blood pressure
- High cholesterol
- Smoking
- Diabetes
- Obesity
- Family history of heart disease under 60
- Physical inactivity
- Stress and psychosocial factors
Symptoms
- Chest discomfort, pressure, heaviness or squeezing; pain may be mild rather than severe
- Discomfort spreading to either or both arms, the jaw, neck, back or upper abdomen
- Shortness of breath
- Sweating, nausea, or vomiting
- Feeling of impending doom
- Chest discomfort is common in both women and men, but a heart attack may cause breathlessness, nausea, unusual fatigue or back or jaw pain without clear chest pain. Mild or silent heart attacks are more common in people with diabetes.
When to see a doctor
If you suspect a heart attack, call your local emergency number immediately, even if symptoms are mild or uncertain. Do not drive yourself. Rest while waiting and follow the dispatcher's advice, including whether aspirin is appropriate. Tell them about allergies, bleeding problems, current medicines or advice not to take aspirin.
Diagnosis
Emergency assessment uses symptoms, an ECG and blood troponin tests. Some heart attacks do not cause ST elevation, so an ECG without this change does not rule one out. Tests may be repeated. Coronary angiography may help identify and treat the affected artery.
Treatments
Primary PCI (angioplasty and stenting)
Emergency angioplasty and stenting can reopen a blocked artery. It is a key treatment for STEMI when it can be delivered promptly; the emergency team chooses the pathway according to the findings and available services.
Thrombolysis
Clot-dissolving medicine may be used for selected STEMI heart attacks when timely angioplasty is not available. The team checks symptom timing, bleeding risk and other contraindications. It is not suitable for every type of heart attack.
Long-term secondary prevention
Dual antiplatelet therapy, statin, ACE inhibitor, beta-blocker, and cardiac rehabilitation are all part of post-heart-attack care to prevent a second event.
Self-care and lifestyle
- Attend cardiac rehabilitation: supervised exercise, education, and psychological support after a heart attack
- Stop smoking immediately as continued smoking after a heart attack significantly increases risk of a second event
- Take all prescribed medications as directed, even when feeling well
- Follow a heart-healthy diet, exercise regularly, and manage stress
Prevention
Addressing modifiable risk factors: not smoking, controlling blood pressure and cholesterol, managing diabetes, and being physically active. Statins are highly effective at preventing first and recurrent heart attacks in high-risk individuals.
Sources for targeted updates
Updated: 24 October 2026. Targeted corrections to frequency, symptoms, urgent-care guidance, diagnosis, treatment, key facts. This update covers the named sections; a full review of the remaining guide is pending.