N‐acetyl‐b‐D‐glucosaminidase: A potential cardiorenal biomarker with a relevant impact on ICD shock therapies and mortality

AIMS: Chronic heart failure may lead to chronic kidney disease. Previous studies suggest tubular markers N-acetyl-b-D-glucosaminidase (NAG) and Kidney-injury-molecule-1 (KIM-1) as potential markers for the cardiorenal syndrome (CRS). The prognostic value of NAG and KIM-1 regarding implantable cardioverter defibrillator (ICD) shock therapies is unknown. METHODS: We included 314 patients with an ICD and collected plasma and urine samples. Urine-values of NAG and KIM-1 got related to urinary creatinine. Outcomes of interest were sustained adequate shock therapies and a combined endpoint of all-cause mortality, rehospitalisation due to congestive heart failure and adequate shock therapies. Follow up time was 32 months (IQR 6-35 months). RESULTS: KIM-1 and NAG were positively correlated with NT-proBNP (KIM-1: r = .34, P < .001; NAG: r = .47, P < .001). NAG was significantly elevated in patients with primary prevention compared with secondary prevention ICD indication (P = .003). According to Kaplan Meier analysis, NAG as well as NT-proBNP were significant predictors for adequate ICD shock therapies and for the combined endpoint (each P < .001). Elevated KIM-1 showed no significant differences (each P = n.s.). In multivariate cox regression analysis, NAG as well as NT-proBNP were both independent predictors for adequate ICD shock therapies as well as the combined endpoint, beside ejection fraction <35% (each P < .05). Diabetes, primary prevention ICD indication, coronary artery disease, eGFR and age were no significant predictors for both endpoints (each P = n.s.). CONCLUSION: Similar to NT-proBNP, NAG showed promising value for overall prognostication in ICD patients. Especially, NAG seems to incorporate an additional prognostic value regarding occurrence of ICD shock therapies.