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Low plasma ascorbic acid independently predicts the presence of an unstable coronary syndrome
J A Vita1, J F Keaney, K E Raby
1Evans Memorial Department of Medicine and Whitaker Cardiovascular Institute, Boston University Medical Center, Massachusetts 02118, USA. jvita@bu.edu
Insights
Plasma antioxidant status, particularly ascorbic acid and thiols, may influence coronary artery disease activity, not its overall extent. Lower levels predict unstable coronary syndromes, suggesting a role in lesion activity.
Area of Science:
- Cardiovascular Medicine
- Biochemistry
- Nutritional Science
Background:
- Increased antioxidant intake is linked to reduced coronary disease risk.
- Mechanisms underlying this association remain debated.
- Investigating plasma antioxidant status in relation to coronary artery disease (CAD) is crucial.
Purpose of the Study:
- To examine the relationship between plasma antioxidant status, the extent of atherosclerosis, and the activity of coronary artery disease.
- To determine if specific antioxidant markers predict unstable coronary syndromes.
Main Methods:
- Plasma samples from 149 patients undergoing cardiac catheterization were analyzed.
- Twelve plasma antioxidant/oxidant markers were measured.
- Correlations were assessed with the extent of atherosclerosis and presence of unstable coronary syndrome.
Main Results:
- No antioxidant markers correlated with the extent of atherosclerosis.
- Lower plasma ascorbic acid predicted unstable coronary syndromes (OR 0.59).
- In patients with significant disease, ascorbic acid (OR 0.56) and total thiols (OR 0.52) predicted unstable syndromes.
Conclusions:
- Findings support the hypothesis that antioxidants influence CAD lesion activity.
- The beneficial effects may stem from modulating disease activity rather than reducing plaque extent.
- Plasma antioxidant status is a potential indicator of coronary artery disease instability.
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 < 0.001), diabetes mellitus (p < 0.001), male gender (p < 0.001) and hypercholesterolemia (p = 0.02) were independent predictors of the extent of atherosclerosis. No antioxidant/oxidant marker correlated with the extent of atherosclerosis. However, lower plasma ascorbic acid concentration predicted the presence of an unstable coronary syndrome by multiple logistic regression (odds ratio [OR] 0.59, 95% confidence interval [CI] 0.40 to 0.89, p = 0.01). The severity of atherosclerosis also predicted the presence of an unstable coronary syndrome (OR 1.7, 95% CI 1.14 to 2.47, p = 0.008) when all patients were considered. When only patients with significant coronary disease were considered (at least one stenosis >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.