People who have had one heart attack are at much higher risk for a second attack. Reducing blood cholesterol levels can greatly slow down (and, in some people, even reverse) the buildup of cholesterol and fat in the wall of the coronary arteries and significantly reduce the chances of a second heart attack. If you have had a heart attack or have coronary disease, your LDL level should be around 100 mg/dL which is even lower than the recommended level of less than 130 mg/dL for the general population.
For more information, go to Cholesterol and The Heart.
Source: National Heart, Lung, and Blood Institute - National Institutes Of Health