Coronary artery disease (CAD) is the most common type of heart disease. It is the leading cause of death in the world in both men and women. Coronary artery disease happens when the arteries that supply blood to heart muscle become hardened and narrowed. This is due to the build up of cholesterol and other material, called plaque on their inner walls. As the build up grows, less blood can flow through the arteries. As a result heart muscle can't get the blood or oxygen it needs. This can lead to chest pain (angina) or a heart attack. Treatment of CAD is aimed at controlling symptoms and slowing or stopping the progression of disease. The method of treatment is based on many factors determined by symptoms, a physical exam, and diagnostic testing.