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 beta = 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.