Coronary arteries can become diseased when cholesterol, a fatlike substance carried in the blood, builds up to form plaque (fatty substances and calcium) in the lining of the artery. Blood and oxygen may no longer flow easily to the heart muscle which may cause angina (pain, discomfort or pressure in the chest that is caused by an insufficient supply of blood to the heart). You may develop a heart attack (myocardial infarction) if blood flow is completely blocked by plaque or by a blood clot that forms inside the narrowed coronary artery. Risk factors for coronary artery disease are gender, age, family history, smoking, high blood pressure, high fat and cholesterol diet, excessive alcohol intake, overweight, lack of exercise and diabetes. Symptoms of coronary artery disease seldom appear until a coronary artery has narrowed by 70% or more.