Association of plasma homocysteine with coronary artery calcification in different categories of coronary heart disease risk

OBJECTIVE: To investigate the association of plasma homocysteine with coronary artery calcification (CAC) in strata based on 10-year risk of coronary heart disease (CHD) in a cohort enriched in persons with hypertension. PARTICIPANTS AND METHODS: Fasting plasma homocysteine was measured by liquid chromatography electrospray tandem mass spectrometry. Coronary artery calcification was measured non-invasively by electron beam computed tomography and CAC score calculated using the method of Agatston et al. The 10-year CHD risk was calculated based on the Framingham risk score. The association of homocysteine with log-transformed CAC score was assessed in the pooled sample and within each risk stratum by linear regression after adjustment for conventional risk factors. RESULTS: In the 1071 participants studied, homocysteine was associated with CAC quantity (P=.01) after adjustment for CHD risk factors (age, male sex, total and high-density lipoprotein cholesterol, diabetes, history of smoking, body mass index, and systolic blood pressure), serum creatinine, and statin and hypertension medication use. When the association was assessed in strata based on 10-year CHD risk, homocysteine was significantly (P=.003) associated with CAC quantity in participants at intermediate 10-year risk of CHD (6%-20%) independent of other risk factors but not in those at lower risk or higher risk. CONCLUSION: Plasma homocysteine is associated with quantity of CAC independent of CHD risk factors. When studied in categories of 10-year CHD risk, the association was significant in participants at intermediate risk but not in those at low or high risk. Plasma homocysteine levels may have clinical utility as a marker of CHD risk in such individuals.