Coronary artery disease (CAD), also called coronary heart disease (CHD) or simply heart disease, is the single largest killer of American men and women in all ethnic groups. When the arteries that supply the myocardium (heart muscle) are diseased, the heart cannot pump blood effectively to adequately perfuse vital organs and peripheral tissues. The organs and tissues need oxygen in arterial blood for survival. When oxygenation and perfusion are impaired, the patient can have life- threatening clinical manifestations and possibly death.