Diagnostic and prognostic value of cystatin C in acute heart failure

Background: The accurate early diagnosis of acute kidney injury (AKI) in patients with acute heart failure (AHF) is an unmet clinical need. Cystatin C might improve the early detection of AKI. Methods: 207 patients presenting to the emergency department with AHF were enrolled. Cystatin C was measured in plasma in a blinded fashion at presentation and serially thereafter. The potential of Cystatin C levels to predict AKI was assessed as the primary endpoint. Long-term mortality was assessed as a secondary endpoint. Results: At presentation, creatinine (140 mu mol/L [91-203] vs. 97 mu mol/L [76-132], p < 0.01) and Cystatin C (2.00 mg/L [1.30-3.08] vs. 1.45 mg/L [1.00-1.90], p < 0.01) levels were significantly higher in AKI compared to Non-AKI patients. The diagnostic accuracy for AKI quantified by the area under the receiver operating characteristic curve was mediocre and comparable for both markers (creatinine 0.68; 95% CI 0.58-78 vs. Cystatin C 0.67; 95% CI 0.58-0.76). Serial measurements of Cystatin C did not further increase the prognostic accuracy for AKI. Cystatin C levels were significantly higher in decedents than in survivors (1.90 mg/L [1.30-2.70] vs. 1.30 mg/L [1.0-1.6], p < 0.001). The combination of Cystatin C and BNP levels significantly improved the prediction of mortality provided by either parameter alone. In multivariable regression analysis Cystatin C remained independently associated with mortality (HR 1.41; 95% CI 1.02-1.95). Conclusion: Plasma Cystatin C levels do not adequately predict AKI in patients with AHF. However, in multivariable regression analysis Cystatin C predicted mortality after the adjustment for baseline renal function, AKI, BNP levels and heart failure risk factors.