Coronary Artery Disease

What Causes Coronary Artery Disease?

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Coronary artery disease is caused by hardening of the arteries, or atherosclerosis. Atherosclerosis occurs when plaque builds up inside the arteries. (Arteries are the blood vessels that carry oxygen-rich blood throughout your body.) Atherosclerosis can affect any arteries in the body. When it occurs in the arteries that supply blood to the heart, it is called coronary artery disease.

Plaque is a fatty material made up of cholesterol, calcium, and other substances in the blood. To understand why plaque is a problem, compare a healthy artery with an artery with atherosclerosis:

A healthy artery is like a rubber tube. It is smooth and flexible, and blood flows through it freely. If your heart has to work harder, such as when you exercise, a healthy artery can stretch to let more blood flow to your body’s tissues.
An artery with atherosclerosis is more like a clogged pipe. Plaque narrows the artery and makes it stiff. This limits the flow of blood to the tissues. When the heart has to work harder, the stiff arteries can't flex to let more blood through, and the tissues don't get enough blood and oxygen.
See a picture of a normal artery and an artery narrowed by plaque.

When plaque builds up in the coronary arteries, the heart doesn't get the blood it needs to work well. Over time, this can weaken or damage the heart. If a plaque tears, the body tries to fix the tear by forming a blood clot around it. The clot can block blood flow to the heart and cause a heart attack.

See a picture of how plaque causes a heart attack.