EFFECTS OF ANTIOXIDANT VITAMIN-C AND VITAMIN-E ON SIGNAL-AVERAGED ELECTROCARDIOGRAM IN ACUTE MYOCARDIAL-INFARCTION

Experimental studies indicate that oxygen-free radicals contribute to ischemic myocardial damage and affect electric properties of cellular membranes. We hypothesize that an association exists between an free r adical-induced component of myocardial injury and altered electric fun ction that underlies the genesis of ventricular late potentials in the course of myocardial infarction. If so, antioxidant vitamins C and E may prevent alterations in the signal-averaged electrocardiogram (SAEC G). To test this hypothesis, we investigated the effect of supplementa tion with vitamins C and E on the indices of the SAECG in patients wit h acute myocardial infarction (AMI). Sixty-one patients with AMI were randomized to receive conventional treatment and vitamins C and E, eac h 600 mg/day, orally for 14 days (supplemented group, n = 33) or conve ntional treatment only (control group, n = 28). SAECG was recorded on days 1 or 2 and between days 9 and 13 (mean 10). Serum ascorbic acid, tocopherol, plasma lipid peroxides, and oxygen-free radical production by isolated leukocytes were measured on days 1 or 2 and between days 12 and 14. in the control group, SAECG showed an increase in mean QRS and low-amplitude (<40 mu V) signal durations, from 99 +/- 10 to 111 /- 13 ms (p <0.001) and from 31 +/- 8 to 38 +/- 10 ms (p <0.001), resp ectively, and a decrease in the roof-mean-square voltage of the last 4 0 ms of the QRS complex, from 36 +/- 25 to 21 +/- 11 mu V (p <0.002). In vitamin-supplemented patients, all these indices remained unchanged . Oxygen-free radical production by isolated leukocytes was decreased compared with that in controls (p <0.02). Supplementation was confirme d by elevation of serum ascorbic acid and tocopherol. Results support the hypothesis that in patients with AMI, oxygen-free radical-induced cellular damage contributes to alterations in electric function of the heart as seen on the SAECG.