Cysteine is a cardiovascular risk factor in hyperlipidemic patients

Several studies have reported that moderate hyperhomocysteinemia is related to an increased risk for atherosclerosis, but few data are available with regard to any other thiol compound having a potential vascular toxicity. Th erefore, we measured both total cysteine and homocysteine plasma levels in patients with hyperlipidemia (242 males and 147 females, 41-65 years old). Homocysteine was higher in males than in females, 13.2 +/- 4.1 versus 11.1 +/- 3.4 mu mol/l (P < 0.0001). The mean cysteine level was 243.3 +/- 45.7 m u mol/l in the whole study population. The subjects were split in two group s, symptomatic patients with cardiovascular disease (n = 106) and asymptoma tic subjects (n = 283). Blood pressure, smoking status, total cholesterol, LDL-cholesterol and triglycerides did not statistically differ between grou ps, but the mean HDL-cholesterol level was lower in symptomatic patients (1 .24 +/- 0.38 versus 1.42 +/- 0.41, P < 0.0001). Cysteine levels were high i n patients with cardiovascular disease than in asymptomatic patients, respe ctively 254.7 +/- 47.7 versus 239.1 +/- 44.3 mu mol/l (P = 0.003). A simila r result was found for homocysteine, respectively 13.1 +/- 4.3 versus 12.2 +/- 3.9 mu mol/l (P = 0.05). To analyse whether cysteine levels were relate d to atherosclerosis independently of age, adjusted levels were compared be tween asymptomatic patients with normal carotid arteries (n = 176), carotid atherosclerosis (n = 107) and symptomatic patients (n = 106). Age adjusted cysteine levels differed significantly between groups (P = 0.027) while th e P-value was of borderline significance for homocysteine (P = 0.09). Odds ratios for having symptomatic cardiovascular disease were 1.81 (95% CI, 1.0 2-3.21) and 2.05 (95% CI, 1.16-3.60) for the mid and highest tertiles of cy steine using the lowest as the reference. After adjustment in a multivariat e model including age, sex, and creatinine, the odds ratio for disease rema ined significant between the highest tertile versus the lowest (OR = 1.89). Adjusted odds ratios were found to be weaker when homocysteine tertiles we re compared. Our data suggest that plasma total cysteine is a risk factor f or atherosclerosis in hyperlipidemic patients. (C) 1999 Elsevier Science Ir eland Ltd. All rights reserved.