Elevated Cystatin C Predicts Higher Mortality in Chronic Heart Failure Independently of Renal Function.

Introduction: Cystatin C (CysC) is a known prognostic marker in cardiovascular diseases and its role in acute heart failure (HF) has been documented.

Methods: We prospectively recruited HF patients followed in a HF clinic. Inclusion criteria: HF diagnosed ≥6 months, optimized evidence-based therapy, and ejection fraction <40% (Heart Failure with reduced ejection fraction). Exclusion criteria: renal replacement therapy and hospitalizations or therapeutic adjustments in the previous 2 months. A venous blood sample and 24-hour urine were collected. Follow-up: 5 years; endpoint: all-cause mortality. CysC was measured and creatinine clearance (CrCl) was calculated using 24-hour urine creatinine excretion. A Receiver operating characteristic curve was used to assess association of CysC with 5-year mortality. The prognostic role of CysC was determined using Cox-regression analysis. The multivariate model included CrCl (24-hour urine).

Results: We evaluated 215 chronic stable Heart Failure with reduced ejection fraction patients. Mean age was 68 years, 72.1% were male. Median CysC = 1.15 mg/L, creatinine = 1.20 mg/dL, and CrCl = 63.6 mL/min. During follow-up, 103 (47.9%) patients died. The area under the curve for CysC in predicting mortality was 0.77 (0.70-0.83). Best cut-off value for death prediction = 1.00 mg/L with a sensitivity = 83.5%, specificity = 56.2%, positive predictive value = 63.7%, and negative predictive value = 78.7%. Multivariate-adjusted (age-, B-type natriuretic peptide-, evidence-based therapy, New York Heart Association class, and CrCl) 5-year mortality Hazard ratio = 2.40 (95% Confidence interval, 1.25-4.61), P value = 0.008 when CysC ≥1.00 mg/L.

Conclusions: Patients with CysC <1.00 mg/L have almost 80% probability of being alive at 5 years; If CysC ≥1.00 mg/L, there is almost 2.5-fold higher death risk independently of B-type natriuretic peptide and CrCl.