Aims: Patients with chronic heart failure are often characterized by impaired renal function, also referred to as cardiorenal syndrome (CRS). The aim of this study was to assess whether novel markers of kidney injury are elevated in chronic heart failure and CRS.
Methods and results: The new renal biomarkers kidney injury molecule-1 (KIM-1), N-acetyl-ß-d-glucosaminidase (NAG) and neutrophil gelatinase-associated lipocalin (NGAL) were assessed from urine samples of 173 individuals. Patients with chronic heart failure (n= 150) were characterized by decreased ejection fraction (32 ± 9% vs. controls 62 ± 4%, P < 0.001) and increased plasma N-terminal pro-brain natriuretic peptide (median 1460 pg/mL, interquartile range (IQR) 630-3000 pg/mL vs. controls 56, IQR 25-64l pg/mL, P < 0.001). Urinary analysis showed that KIM-1 was significantly elevated in heart failure patients compared with healthy controls (1100, IQR 620-1920 vs. 550, IQR 320-740 ng/g urinary creatinine, P < 0.001). Further, KIM-1 increased significantly with decreasing left ventricular function (r = -0.37, P < 0.001) and severity of New York Heart Association (NYHA)-class (r = 0.5, P < 0.001). N-acetyl-ß-d-glucosaminidase showed a weaker response but correlated significantly with left ventricular dysfunction (r = -0.18, P= 0.015) and more severe clinical condition (r = 0.22, P= 0.04). In contrast, NGAL showed no significant correlation. Kidney injury molecule-1 and NAG were also predictors of all-cause mortality and the composite of all-cause mortality and rehospitalization for heart failure (all P < 0.05).
Conclusions: Kidney injury molecule-1 and NAG are elevated in symptomatic heart failure. This finding may be present in patients with apparently normal kidney function and indicates tubular injury in chronic heart failure. Kidney injury molecule-1 and NAG are potential markers of CRS with additional prognostic value.