Causes

A heart attack occurs when one or more of your coronary arteries becomes blocked. Over time, a buildup of fatty deposits, including cholesterol, form substances called plaques, which can narrow the arteries (atherosclerosis). This condition, called coronary artery disease, causes most heart attacks.

During a heart attack, a plaque can rupture and spill cholesterol and other substances into the bloodstream. A blood clot forms at the site of the rupture. If the clot is large, it can block blood flow through the coronary artery, starving the heart of oxygen and nutrients (ischemia).

You might have a complete or partial blockage of the coronary artery.

• A complete blockage means you've had an ST elevation myocardial infarction (STEMI).
• A partial blockage means you've had a non-ST elevation myocardial infarction (NSTEMI).

Diagnosis and treatment might be different depending on which type you've had.

Another cause of a heart attack is a spasm of a coronary artery that shuts down blood flow to part of the heart muscle. Using tobacco and illicit drugs, such as cocaine, can cause a life-threatening spasm.

Infection with COVID-19 also may damage your heart in ways that result in a heart attack.