Coronary Artery Disease Coronary artery disease (CAD) is the number one killer in the United States, causing over 500,000 deaths per year. Coronary artery disease results when fatty deposits called plaque build up in arteries in the heart, causing them to narrow and harden. If the arteries become blocked, the heart receives less oxygen and can become damaged. In most people, CAD begins in young adulthood and gradually develops throughout life. While some risk factors for CAD cannot be controlled, there are many important lifestyle choices that you can make that will lower your risk for the disease. Check out Risk Factors and Treatment to learn more. © 2007 Museum of Science and Industry, Chicago. All rights reserved.