Cystatin C and muscle mass in patients with heart failure

ABSTRACT Background Estimated glomerular filtration rate (GFR) from cystatin C (eGFRcys) is often considered a more accurate method to assess GFR compared to estimated GFR from creatinine (eGFRcr) in the setting of heart failure (HF) and sarcopenia because cystatin C is hypothesized to be less affected by muscle mass than creatinine. We evaluated: 1) the association of muscle mass with cystatin C; 2) the accuracy of eGFRcys; 3) association of eGFRcys with mortality given muscle mass. Methods and Results We included 293 patients admitted with HF. Muscle mass was estimated with a validated creatinine excretion-based equation. Accuracy of eGFRcys and eGFRcr was compared to measured creatinine clearance (mClcr). Cystatin C and creatinine were 31.7% and 59.9% higher per 14 kg higher muscle mass at multivariable analysis (both p 0.19). Conclusions Cystatin C levels were associated with muscle mass in patients with HF, which could potentially decrease the accuracy of eGFRcys. In HF where aberrations in body composition are common eGFRcys, like eGFRcr may not provide accurate GFR estimations and results should be interpreted cautiously.