Beneficial effects of vitamin E treatment in acute myocardial infarction

Vitamin E (Vit E), an antioxidant, is considered to prolong survival in patients and animals after myocardial infarction. Because myocardial infarction is associated with arrhythmia and heart dysfunction, this study tested the hypothesis that early treatment with Vit E reduces mortality because of its protective effects against arrhythmia and cardiac dysfunction induced by acute myocardial infarction.

Rats were randomly divided into 4 groups: sham control, myocardial infarcted, Vit E-treated sham control, and Vit E-treated infarcted animals. Myocardial infarction was induced by ligation of the left anterior descending coronary artery. Treated animals received Vit E (25 mg/kg/d) through a gastric tube beginning 1 hour after the coronary occlusion, whereas control rats received tap water.

Electrocardiograms (lead II) at 1, 3, 7, and 21 days after coronary occlusion in the untreated animals showed ST-segment elevation, abnormal Q waves, premature ventricular complex (PVC), and QTc prolongation. Conversely, Vit E-treated rats showed attenuated ST-segment changes, fewer abnormal Q waves, and decreased incidence of PVC after coronary occlusion. Total mortality was reduced from 38% to 16%, whereas the infarct size was decreased from 44.2% to 22.3% in infarcted rats treated with Vit E. The depression in left ventricular function as well as elevation of malondialdehyde content and conjugated diene formation in the 21-day infarcted rat hearts were prevented by Vit E treatment.

These results indicate that Vit E may exert beneficial effects on the heart by reducing oxidative stress in acute myocardial infarction.