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 (CAD) typically begins when the inside walls of the coronary arteries are damaged, due to one or more underlying conditions, 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 a picture of atherosclerosis.)

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

However, heart muscle cells can die if blood flow is severely reduced or completely blocked for a period of time. This is called myocardial infarction, or heart attack.