Low Plasma Ascorbic Acid Independently Predicts the Presence of an Unstable Coronary Syndrome

Abstract Objectives. This study sought to investigate the relations between plasma antioxidant status, extent of atherosclerosis and activity of coronary artery disease. Background. Previous studies indicate that increased antioxidant intake is associated with decreased coronary disease risk, but the underlying mechanisms remain controversial. Methods. Plasma samples were obtained from 149 patients undergoing cardiac catheterization (65 with stable angina, 84 with unstable angina or a myocardial infarction within 2 weeks). Twelve plasma antioxidant/oxidant markers were measured and correlated with the extent of atherosclerosis and the presence of an unstable coronary syndrome. Results. By multiple linear regression analysis, age (p 50%), ascorbic acid concentration (OR 0.56, 95% CI 0.37 to 0.85, p = 0.008) and total plasma thiols (OR 0.52, 95% CI 0.34 to 0.80, p = 0.004) predicted the presence of an unstable coronary syndrome, whereas the extent of atherosclerosis did not. Conclusions. These data are consistent with the hypothesis that the beneficial effects of antioxidants in coronary artery disease may result, in part, by an influence on lesion activity rather than a reduction in the overall extent of fixed disease.