Causes of heart attack.

Causes

Coronary artery disease causes most heart attacks. In coronary artery disease, one or more of the heart (coronary) arteries are blocked. This is usually due to cholesterol-containing deposits called plaques. Plaques can narrow the arteries, reducing blood flow to the heart.

If a plaque breaks open, it can cause a blood clot in the heart.

A heart attack may be caused by a complete or partial blockage of a heart (coronary) artery. One way to classify heart attacks is whether an electrocardiogram (ECG or EKG) shows some specific changes (ST elevation) that require emergency invasive treatment. Your health care provider may use ECG results to describe these types of heart attacks.

• An acute complete blockage of a medium or large heart artery usually means you've had an ST elevation myocardial infarction (STEMI).
• A partial blockage often means you've had a non-ST elevation myocardial infarction (NSTEMI). However, some people with NSTEMI have a total blockage.

Not all heart attacks are caused by blocked arteries. Other causes include:

• Coronary artery spasm. This is a severe squeezing of a blood vessel that's not blocked. The artery generally has cholesterol plaques or there is early hardening of the vessel due to smoking or other risk factors. Other names for coronary artery spasms are Prinzmetal's angina, vasospastic angina or variant angina.
• Certain infections. COVID-19 and other viral infections may cause damage to the heart muscle.
• Spontaneous coronary artery dissection (SCAD). This life-threatening condition is caused by a tear inside a heart artery.