Cystatin C, a novel measure of renal function, is an independent predictor of cardiac events in patients with heart failure

Background: Cystatin C, a novel endogenous marker of glomerular filtration rate, has been reported as more sensitive to detect renal insufficiency than creatinine. The purpose of the present study was to examine the clinical significance of serum cystatin C level in patients with mild to moderate heart failure. Methods and Results: Serum levels of cystatin C were measured by an enzyme immunoassay in 140 patients with heart failure and 64 control subjects without heart failure. Patients were prospectively followed during a median follow-up period of 480 days, with the end points of cardiac death and progressive heart failure requiring rehospitalization. Serum levels of cystatin C were higher in patients with heart failure than in control subjects (1.14 +/- 0.60 ng/mL versus 0.72 +/- 0.14 ng/mL, P < .001). The Cox multivariate proportional hazard analysis revealed that a change of 1 standard deviation (SD) in cystatin C level was the one of independent predictor for cardiac events (hazard ratio, 1.94; 95% confidence interval, 1.29-6.64; P < .01). The cardiac event rate was markedly higher in patients with elevated cystatin C level (>= 1.0 ng/mL) than in those with normal level (<= 1.0 ng/mL) (38.7% versus 10.3%, P < 0.001). Furthermore in patients with normal creatinine levels (n = 91), the cardiac event rate was similarly higher in patients with elevated cystatin C than in those with normal levels (29.2% versus 7.5%, P = .002). Conclusion: Elevation of serum cystatin C, a new marker of renal function, provides promising prognostic information for clinical outcome in patients with mild to moderate heart failure.