Other names:

•           Myocardial infarction (MI);

•           Acute myocardial infarction (AMI);

•           Acute coronary syndrome;

•           Coronary thrombosis;

•           Coronary occlusion.

A heart attack happens when the flow of oxygen-rich blood to a section of heart muscle suddenly becomes blocked and the heart can’t get oxygen. If blood flow isn’t restored quickly, the section of the heart muscle begins to die. More than a million Americans have heart attacks each year. A heart attack is also called a myocardial infarction (MI). "Myo" means muscle, "cardial" refers to the heart, and "infarction" means the death of tissue because of a lack of blood supply. This tissue death can cause lasting damage to your heart muscle.

Heart attack treatment works best when it’s given right after the symptoms occur. If you think you or someone else is having a heart attack, even if you’re not sure, call 9–1–1 right away.

According to the Centers for Disease Control and Prevention (CDC) myocardial infarction happens every 40 seconds.

Heart attacks most often occur as a result of ischemic heart disease, also called coronary heart disease or coronary artery disease. Ischemic heart disease is a condition in which a waxy substance called plaque builds up inside the coronary arteries. These arteries supply oxygen-rich blood to the heart.

When plaque builds up in the arteries, the condition is called atherosclerosis. The buildup of plaque occurs over many years.

Eventually, an area of plaque can rupture (break open) inside an artery. This causes a blood clot to form on the plaque's surface. If the clot becomes large enough, it can mostly or completely block blood flow through a coronary artery.

If the blockage isn't treated quickly, the portion of heart muscle fed by the artery begins to die. Healthy heart tissue is replaced with scar tissue. This heart damage may not be obvious, or it may cause severe or long-lasting problems.