Effect of lipid-lowering therapy on myocardial ischemia.

Abstract

Myocardial blood flow in patients with coronary artery disease depends on the severity of the coronary narrowings and the functional status of the coronary vessels. Coronary atherosclerotic plaques, which contain high concentrations of lipids, are more sensitive to change in coronary tone. The increased tendency of these active plaques for vasoconstriction is caused by abnormal endothelial function. Because regression of significant coronary plaques is highly unlikely, effort is made to improve endothelial function, thereby improving myocardial blood flow. Reduction of the cholesterol level by lipid-lowering drugs is associated with restoration of the vasodilatory response of the coronary arteries, thereby reducing the likelihood of plaque rupture and its consequences: myocardial infarction and death. Myocardial ischemia during daily life is induced by increased demand and increased coronary tone; therefore, it was not surprising that recent studies have indicated that cholesterol lowering reduced the frequency of daily ischemic episodes. Because improvement in endothelial function is already observed within a few weeks/months of lipid lowering, it is hoped that this therapy will rapidly reduce the frequency and severity of myocardial ischemia and its clinical expression, angina pectoris. At a later phase (1-2 years), cholesterol lowering will also reduce major cardiac events.