Impact of Myocardial Function on Cystatin C Measurements in Chronic Systolic Heart Failure

Background: The influence of myocardial function on plasma levels of cystatin C (CysC), a sensitive marker of renal function, in chronic systolic heart failure (HF) has not been well established. Methods: We prospectively identified 139 subjects with stable, chronic HF (left ventricular ejection fraction ≤ 35%) and measured plasma levels of CysC. We prospectively tracked patients' long-term adverse clinical outcomes (death, cardiac transplantation, and HF hospitalizations). Results: Plasma levels of CysC were elevated in 41% of patients with preserved renal function and directly correlated with N-terminal prohormone brain natriuretic peptide (r = 0.57, P < .0001). There was a significant association between CysC and mitral E/septal E' ratio (r = 0.34, P < .001), right ventricular systolic dysfunction severity (r = 0.30, P < .001), and mitral regurgitation severity (r = 0.31, P < .001), but not left ventricular ejection fraction. At the cutoff of 1.23 mg/dL, CysC remains a significant independent risk factor for adverse clinical outcomes (hazard ratio 1.88, 95% confidence interval 1.15-3.09, P = .012) after adjusting for estimated glomerular filtration rate, left ventricular ejection fraction, and E/septal E'. Conclusion: CysC is associated with more advanced left ventricular diastolic dysfunction and right ventricular systolic dysfunction and remains an independent predictor of long-term prognosis in chronic systolic HF after adjusting for myocardial factors.