Cystatin C and asymptomatic coronary artery disease in patients with metabolic syndrome and normal glomerular filtration rate

BACKGROUND All of the components of metabolic syndrome (MetS) have been regarded as risk factors for coronary artery disease (CAD). Early detection of CAD in asymptomatic patients with MetS remains a challenge. Cystatin C,which has been proposed as a novel marker of renal dysfunction,is correlated with mortality in CAD, The purpose of the study was to evaluate whether cystatin C is a potential marker of asymptomatic CAD in MetS patients with normal kidney function. METHODS A total of 211asymptomatic MetS patients without prior history of CAD patients were included in a cross-sectional study. Patients were divided into MetS with asymptomatic CAD (n=136) and MetS without CAD (n=75) groups according to coronary angiograph results. Serum cystatin C levels were measured using particle enhanced immunonephelometric assays. We first assessed whether there is an independent association of cystatin C with the presence and severity of asymptomatic CAD. Then, we investigated the association between cystatin C and other biochemical risk factors for atherosclerosis. RESULTS Serum cystatin C levels in patients with asymptomatic CAD were significantly higher than those without CAD (P=0.004). A multiple logistic regression analysis demonstrated cystatin C was independently associated with the presence of asymptomatic CAD (OR=1.326, 95%CI: 1.086-1.619). On receiver operating characteristics (ROC) analysis, the area under the curve (AUC) was 0.622 (95% CI: 0543-0.701, P=0.003), and cystatin C showed a moderate predictive value. Furthermore, cystatin C was independently correlated with Gensini score (standardized β=0.183, P=0.007), and serum cystatin C levels increased with the increasing of number of disease vessels (P=0.005). In a multiple stepwise regression analysis, uric acid (UA)(P<0.001), body mass index (BMI)(P=0.002), triglyceride(TG)(P=0.03), estimated glomerular filtration rate (eGFR)(P<0.001), and fibrinogen(P=0.001) were independently associated with cystatin C. CONCLUSIONS Serum cystatin C in our study was significantly associated with the presence and severity of asymptomatic CAD in MetS patients with normal kidney function, suggesting that cystatin C is probably more than a marker of glomerular filtration rate.