RESUMO
BACKGROUND: Cystatin C has emerged as a new biomarker of renal function that has been found to predict adverse cardiovascular outcomes, especially heart failure (HF). Evidence of the usefulness of cystatin C in patients with heart failure with preserved ejection fraction (HFPEF) remains sparse. It is hypothesized that serum cystatin C levels in HFPEF has prognostic value. METHODS AND RESULTS: Cystatin C, urea nitrogen, creatinine, and N-terminal proBNP-type natriuretic peptide levels were measured on admission in 218 consecutive patients with HF and left ventricular ejection fraction >45%, as measured by Doppler echocardiography. The primary end point was all-cause mortality and/or readmission at 1 year. We determined the adjusted hazard ratio (HR) by Cox regression model. During the 1-year follow-up period, 70 patients (32.2%) died, and 126 patients (57.8%) died and/or required rehospitalization. Serum cystatin C levels by quartiles were associated with increased risk for adverse events. Kaplan-Meier survival curves showed significantly increased primary end point with each quartile of cystatin C (log rank <0.001). Patients in the highest quartile of cystatin C level were at increased adjusted risk for the primary end point (HR 3.40; 95% confidence interval [CI] 1.86-6.21; P < .0001) and all-cause mortality (HR 8.14; 95% CI 1.21-23.26; P < .01). Furthermore, high serum cystatin C levels were also associated with poor prognosis despite normal or mildly reduced renal function. CONCLUSIONS: Serum cystatin C level on admission in patients with HFPEF is a strong and independent predictor of an unfavorable outcome. This relationship remains in patients without advanced renal dysfunction.