Coronary artery disease is caused by the buildup of plaque on the inside of your coronary arteries. In most people, plaque buildup begins early in life and gradually develops over a lifetime.¹

Coronary artery disease typically begins when the inside walls of the coronary arteries are damaged because of another health problem, such as:

• High cholesterol.
• High blood pressure.
• Diabetes.
• Smoking.

Plaque, which is made up of excess cholesterol, calcium, and other substances in your blood, builds up on the damaged inner walls of your coronary arteries. This process usually occurs throughout the body and is called atherosclerosis, or "hardening of the arteries." See pictures of atherosclerosis and how high blood pressure damages arteries.

Over time, plaque buildup narrows the coronary arteries and can lead to ischemia (insufficient blood flow to the heart muscle). Ischemia (say "is-KEE-mee-uh") can weaken the heart muscle, but it usually does not cause heart muscle cells to die.

But heart muscle cells can die if blood flow is severely reduced or completely blocked for a period of time. This can happen if plaque breaks apart and makes a clot that blocks an artery. This can cause myocardial infarction, or heart attack.