EFFECTS OF DIETARY SUPPLEMENTATION WITH ALPHA-TOCOPHEROL ON MYOCARDIAL INFARCT SIZE AND VENTRICULAR ARRHYTHMIAS IN A DOG-MODEL OF ISCHEMIA-REPERFUSION

Objectives. We investigated whether dietary supplementation with the a ntioxidant vitamin alpha-tocopherol (500 mg daily) might reduce lethal ventricular arrhythmias and infarct size. Background. Previous studie s suggested that dietary supplementation with alpha-tocopherol may be associated with a reduced risk of ischemic heart disease. However, the mechanism of this protection remains unknown. Methods. Beagle dogs we re randomized to either a supple mented or a control group. Because of the low mortality rate in the supplemented group, five dogs were adde d to the control group. After 2 months, dogs were anesthetized and und erwent a 2-h coronary artery occlusion and 6-h reperfusion. Plasma vit amin E, retinol and malondialdehyde concentrations were assessed in al l dogs. Results. Fourteen dogs (11 of 25 control vs. 3 of 19 supplemen ted dogs, p < 0.05) developed ventricular fibrillation during either i schemia or reperfusion. Malondialdehyde concentrations were higher in dogs that subsequently developed arrhythmias (2.7 +/- 0.2 mu mol/liter , mean +/- SEM) compared with dogs that did not (2.1 +/- 0.2 mu mol/li ter, p = 0.03). Among survivors with significant ischemia, infarct siz e was larger in supplemented (n = 12, 58.5 +/- 3.3% of area at risk) t han in control (n = 11, 41.9 +/- 6.5%, p < 0.04) dogs. In addition, fo r a given collateral how supplemented dogs (n = 16) developed larger i nfarct size than control dogs (n = 15, p < 0.001, analysis of covarian ce). Conclusions. The data suggest that dietary alpha tocopherol suppl ementation prevented lethal ventricular arrhythmias associated with is chemia and reperfusion. However, its influence on infarct size and lon g-term prognosis warrants further investigation.