Coronary artery disease (CAD) is a chronic disease in which the coronary arteries gradually harden and narrow (atherosclerosis). This condition is also referred to as coronary heart disease.

 CAD is the most common form of cardiovascular disease in the United States and the leading cause of heart attacks. It is the leading single killer of American men and women, responsible for one of every five deaths in 2003, according to the American Heart Association. About 83 percent of people who die as a result of CAD are 65 or older. In 50 percent of men and 64 percent of women who die suddenly from CAD, there were no previous symptoms. Most recent statistics also show CAD as a leading cause of premature and permanent disability among American workers.

CAD patients tend to have periodic episodes where the heart is not receiving enough oxygen-rich blood (cardiac ischemia). Some patients feel no symptoms during these episodes (silent ischemia), while others may experience significant chest pain, pressure or discomfort (angina). If an episode of cardiac ischemia is severe or lengthy, it could trigger cardiac arrest (in which the heart stops beating).