The buildup of fats, cholesterol and other substances in and on the artery walls.

Atherosclerosis happens when fats, cholesterol and other substances build up in and on the artery walls. The buildup also is called plaque. The condition can make arteries narrow. It may lower or block blood flow to the heart. If plaque breaks open, it can cause a blood clot that triggers a heart attack.

Mild atherosclerosis usually doesn't cause symptoms. If symptoms happen, they depend on which artery is narrowed or clogged. For example, atherosclerosis of a heart artery can cause chest pain or pressure.

Treatment includes lifestyle changes. Eat healthy, exercise and do not smoke. Some people need medicines or a heart procedure and surgery.