Hyperhomocystinemia - A risk factor or a consequence of coronary heart disease?

Background: Mild hyperhomocystinemia has been suggested as an indicator of an increased risk of cardiovascular disease. Objective: To examine whether serum homocysteine concentration is a predict or of coronary heart disease (CHD) events. Methods: A case-control study, nested in a population-based cohort study wa s used. During a follow-up of 13 years, 166 major coronary events (death fr om CHD or nonfatal myocardial infarction) occurred in men with evidence of heart disease at baseline and 272 events in men without a history of heart disease. Two controls per case were selected by individual matching. Results: Among men with known heart disease at baseline, the relative risk (95% confidence interval) of CHD events adjusted for age, smoking, hyperten sion, diabetes mellitus, serum cholesterol level, body mass index, and alco hol consumption was 2.23 (95% confidence interval, 1.03-4.85) in the highes t serum homocysteine quintile compared with the lowest quintile. Among the men free of heart disease at baseline, the corresponding relative risk was 0.90 (95% confidence interval, 0.51-1.60). Conclusions: This prospective study does not support the hypothesis that a high concentration of serum homocysteine is a risk factor for coronary even ts in a population free of heart disease. However, it does suggest that mil d hyperhomocystinemia predicts secondary coronary events in men with heart disease, possibly as a consequence of atherosclerotic changes.