Association of plasma cystatin C levels with angiographically documented coronary artery disease in patients of Indian origin

SummaryBackgroundRenal impairment in patients with coronary artery disease (CAD) is common and increases morbidity and mortality. Estimation of glomerular filtration rate (GFR) by measuring serum creatinine (Cr) or Cr clearance has limitations. Cystatin C is a novel marker for renal function that is very sensitive and specific for GFR estimation. The utility of plasma cystatin C (PCyC) in patients with CAD needs further study, especially in the developing world, where CAD is rising exponentially.Methods and resultsIn a prospective study of 150 patients undergoing coronary angiography, median PCyC was 1.45 mg/L; patients with levels ≥1.45 mg/L were older, had higher mean number of diseased coronary vessels, more frequently had triple vessel disease (TVD), and diffuse CAD on angiography. This association of higher PCyC levels with CAD remained robust even after excluding patients with eGFR < 60 ml/min/1.73 m2. The relative risk (RR) of having TVD or diffuse CAD in the overall cohort was 1.7 and 1.9, while it was 1.91 and 2.3 respectively in those with eGFR ≥ 60 ml/min/1.73 m2, with PCyC levels more than median. Categorization of the entire cohort and those with eGFR ≥ 60, into tertiles based on 33rd and 66th percentiles of PCyC maintained the association of cystatin C with more severe CAD.ConclusionIn Indian patients with CAD, higher PCyC levels are associated with more severe CAD. The association of PCyC with severe CAD remains robust even in patients with normal or mildly impaired renal function. Cystatin C may have potential clinical usefulness as a marker for identification of high risk CAD patients.