Role of Cystatin C in coronary heart disease patients with metabolic syndrome

Introduction: Cystatin C is a non-glycosylated protein. It is used mainly as a biomarker of renal functions. All of the components of metabolic syndrome (MetS) have been regarded as risk factors for coronary artery disease (CAD). Cystatin C, which has been proposed as a novel marker of renal dysfunction, is correlated with mortality in CAD. Aim of work: This present study was designed to investigate the association of cystatin C with the presence and severity of CAD in patients with MetS with normal kidney function and to explore the relationship between cystatin C and other risk factors for atherosclerosis. Materials and Methods: The study included 35 MetS patients with CAD (group I) and 35 MetS patients without CAD (group II). All patients were submitted to full clinical assessment including: history taking, clinical examination, body mass index (BMI) , waist circumference (WC), fasting blood sugar, 2-hours postprandial blood sugar, liver and kidney function tests, uric acid, microalbuminuria, lipid profiles and HbA1c . In addition to measurement of serum fibrinogen, serum cystatin C, coronary angiography, electrocardiograph study and radiological investigations. Results: Cystatin C levels were significantly higher in MetS patients with CAD than MetS patients without CAD. Serum cystatin C was positively correlated with WC, low density lipoprotein -cholesterol (LDL-C), uric acid (UA), serum creatinine (SCr) and fibrinogen and negatively correlated with glomerular filtration rate (GFR) and high density lipoprotein -cholesterol (HDL-C). After further adjustment for age, sex and GFR, correlations remained significant between cystatin C and UA, fibrinogen, WC, LDL-C and HDL-C, also new positive correlations were observed between cystatin C and TG and BMI. Cystatin C was the most significant predictor of CAD followed by fibrinogen and FPG. Patients with higher cystatin C values had higher degrees of coronary artery injuries compared with patients with lower levels. At a cut off value of?0.82 mg/L; Cystatin C had a sensitivity of (76.5%) and specificity of (75.4%) for prediction of CAD. Conclusion: Serum cystatin C was significantly associated with the presence and severity of CAD in MetS patients with normal kidney function, suggesting that cystatin C could be a new marker for prediction of the presence and severity of CAD in patients with metabolic syndrome.