Coronary artery disease: false-colour angiogram of the heart showing stenosis (obstruction) in a major coronary artery, one of the arteries that supply the heart with blood. The stenosed section of artery is represented by the break in the orange ribbon at top left. Arteries become obstructed by the build-up of atheroma, a fatty plaque that develops on the inner arterial wall. The result, coronary artery disease, involves a reduction in blood supply to the heart (ischaemia) which may provoke the chest pains of angina pectoris. In severe cases, the total blockage of an artery leads to the death of heart muscle (myocardial infarction), a heart attack.