How does a heart attack affect the body?

A heart attack affects the body by damaging the heart muscle. Without oxygen, the heart muscle begins to die and scar tissue forms there instead. The damage may lead to long-lasting problems. Complications after a heart attack include irregular heartbeat (arrhythmia), heart rupture (myocardial rupture), heart failure, leaking heart valves, low blood pressure, and swelling of the heart sac (pericarditis).