What is a heart attack?

A heart attack is an interruption in the rhythmic beating of your heart that may happen for any number of reasons. Blood - and therefore oxygen - stop flowing to your brain and other vital organs and can result in severe damage and even death.

A heart attack (also called myocardial infarction) occurs when part of the heart muscle is damaged or dies because it isn't receiving oxygen. Oxygen is carried to the heart by the arteries (blood vessels). Most heart attacks are caused by a blockage in these arteries. Usually the blockage is caused by atherosclerosis, which is the buildup of fatty deposits (called plaque) inside the artery.

Heart attacks can also be caused by a blood clot that gets stuck in a narrow part of an artery leading to the heart. Clots are more likely to form where atherosclerosis has made an artery narrower.