CAD stands for coronary artery disease, according to MedicineNet. Coronary artery disease is the blockage of one or more of the blood-supplying arteries in the heart. This is typically due to a hardening of the arteries.
CAD starts when plaque, or hard cholesterol, builds in the artery, forming clots. Plaque clots impede the flow of blood through the artery. Coronary artery disease is a cause of death and illness. Symptoms of CAD include chest pain, heart attack and sudden death, according to MedicineNet. Treatments for coronary artery disease include balloon angioplasty, stent use in the arteries and bypass heart surgery.