Effects of dietary supplementation with alpha-tocopherol on myocardial infarct size and ventricular arrhythmias in a dog model of ischemia-reperfusion.
OBJECTIVE
We investigated whether dietary supplementation with the antioxidant vitamin alpha-tocopherol (500 mg daily) might reduce lethal ventricular arrhythmias and infarct size.


BACKGROUND
Previous studies 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 were randomized to either a supplemented or a control group. Because of the low mortality rate in the supplemented group, five dogs were added to the control group. After 2 months, dogs were anesthetized and underwent a 2-h coronary artery occlusion and 6-h reperfusion. Plasma vitamin E, retinol and malondialdehyde concentrations were assessed in all dogs.


RESULTS
Fourteen dogs (11 of 25 control vs. 3 of 19 supplemented dogs, p < 0.05) developed ventricular fibrillation during either ischemia or reperfusion. Malondialdehyde concentrations were higher in dogs that subsequently developed arrhythmias (2.7 +/- 0.2 mumol/liter, mean +/- SEM) compared with dogs that did not (2.1 +/- 0.2 mumol/liter, p = 0.03). Among survivors with significant ischemia, infarct size was larger in supplemented (n = 12, 58.5 +/- 3.3% of area at risk) than in control (n = 11, 41.9 +/- 6.5%, p < 0.04) dogs. In addition, for a given collateral flow, supplemented dogs (n = 16) developed larger infarct size than control dogs (n = 15, p < 0.001, analysis of covariance).


CONCLUSIONS
The data suggest that dietary alpha-tocopherol supplementation prevented lethal ventricular arrhythmias associated with ischemia and reperfusion. However, its influence on infarct size and long-term prognosis warrants further investigation.
Sebbag
L
L
Institut National pour la Santé et la Recherche Medicale (INSERM), Unit 63, Lyon, France.
Forrat
R
R
Canet
E
E
Renaud
S
S
Delaye
J
J
de Lorgeril
M
M
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D004195:Disease Models, Animal; D004285:Dogs; D005527:Food, Fortified; D006439:Hemodynamics / Q000187:drug effects; D009203:Myocardial Infarction / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D015428:Myocardial Reperfusion Injury / Q000097:blood / Q000150:complications / Q000188:drug therapy* / Q000473:pathology; D011897:Random Allocation; D017180:Tachycardia, Ventricular / Q000517:prevention & control; D014810:Vitamin E / Q000097:blood / Q000494:pharmacology / Q000627:therapeutic use*
D014810:Vitamin E