Cystatin C in heart failure is nothing more than a bystander of glomerular filtration.

Background: Cystatin is an ubiquitous protease inhibitor involved in degradation of cellular proteins and has recently been associated with increased risk of cardiovascular disease and heart failure independent of renal function. We tested whether cystatin in heart failure is only associated with renal function or also with echocardio-Doppler parameters and factors of myocardial remodeling (C-reactive protein, endothelin, and natriuretic peptides).

Methods: This was an observational study conducted in 100 adult Caucasian outpatients with NYHA class I-II heart function without diabetes and ischemic heart, 50 with idiopathic dilated cardiomyopathy (DCM) and 50 with uremic cardiomyopathy undergoing hemodialysis (HD). Multiple linear regression analysis was performed on cystatin concentration using clinical, laboratory (creatinine, high sensitivity C-reactive protein, endothelin, B-type natriuretic peptide [BNP]) and echocardio-Doppler data as explanatory variables.

Results: The heart was more severely involved in DCM patients (worse ejection fraction, diastolic volume index, index of myocardial performance, left ventricular mass index). Mean values of cystatin, creatinine, BNP and C-reactive protein in HD compared with DCM patients were 6, 9, 5 and 3 times higher, respectively. Mean values of endothelin were comparable in both groups. Cystatin significantly correlated with creatinine in both groups (r=0.50 in DCM and r=0.37 in HD, and r=0.95 in pooled groups). In the multiple regression analysis, only disease group and creatinine within groups were significant independent factors that accounted for 94% of the variability of cystatin.

Conclusion: Renal function was the determinant of cystatin in a concentration range of 6 times regardless of severity of heart involvement.