Urinary NT-proBNP is Independently Associated with Long-term Prognosis of Mortality in Chronic Heart Failure

Aims: Plasma NT-proBNP is the established heart failure marker. Recently, several studies showed that NT-proBNP may have potential as a urinary marker due to its renal arterio-venous clearance. The objective of this study was to assess the prognostic capacity of urinary NT-proBNP for patients with chronic heart failure. Methods: NT-proBNP (Elecsys proBNP®, Roche) was assessed simultaneously in fresh spot urine and plasma from 149 patients with chronic heart failure. During a 5-year-follow-up, data was obtained regarding allcause mortality (n= 47) and a combined endpoint of all-cause-mortality and rehospitalisation due to congestive heart failure (n= 67). Results: Urinary and plasma NT-proBNP were both significantly elevated in patients suffering from an event compared to patients without event (each p< 0.05). Urinary NT-proBNP above the 75th percentile incorporated significant prognostic information regarding all-cause mortality and the combined endpoint (each p<0.05). In cox-regression analysis, urinary NT-proBNP as well as plasma NT-proBNP were both independent predictors for all-cause mortality (each p< 0.05), beside age, diabetes and ejection fraction (EF). Only plasma NT-proBNP was a significant predictor for the combined endpoint (p <0.05; urinary NTproBNP p= n.s.), beside age, male gender, diuretic use and EF. The combination of urinary NT-proBNP and plasma NT-proBNP showed additive prognostic value compared with plasma NT-proBNP alone. Conclusions: Urinary NT-proBNP incorporated significant and independent predictive value, especially regarding all-cause mortality. Measurement of urinary NT-proBNP seems to be a promising method for heart failure prognostication.