Prognostic utility of B-type natriuretic peptides in patients with heart failure and renal dysfunction

BACKGROUND Renal dysfunction is considered a confounding variable in the interpretation of B-type natriuretic peptides (BNPs) and their amino-terminal fragments (NT-ProBNP) in patients with heart failure (HF). Our aim was to investigate the prognostic utility of BNPs and NT-proBNP in HF outpatients with renal dysfunction, and compare the prognostic significance of the corresponding BNP/NT-ProBNP levels in patients with and without renal dysfunction. METHODS A total of 2076 patients from 13 HF clinics in the Norwegian Heart Failure Registry were investigated. The BNP/NT-ProBNP levels were categorized centre-wise into four groups using the quartile limits found in patients with preserved renal function. Patients with renal dysfunction, i.e. glomerular filtration rate (GFR) ≤60 mL/min/1.73 m2, were then assigned to BNP groups 1-4 centre-wise according to their level of natriuretic peptides. RESULTS Renal dysfunction was present in 37.5% of the patients, of whom the majority (59.1%) had levels of natriuretic peptide in the highest BNP group. Patients with renal dysfunction and BNP levels in the lower three BNP groups had similar 2-year survival as patients without renal dysfunction and comparable BNP levels [crude hazard ratio (HR) 1.25, 95% CI 0.82-1.89, P = 0.302, multiple adjusted HR 0.85, 95% CI 0.54-1.33, P = 0.457]. Beyond 2 years of follow-up, renal dysfunction predicted all-cause mortality irrespective of the level of natriuretic peptides at the start of follow-up. CONCLUSION In HF outpatients, the BNP/NT-ProBNP level predicted 2-year mortality irrespective of renal function and provided important prognostic information on patients with renal dysfunction.