Amino-terminal pro-brain natriuretic Peptide, renal function, and outcomes in acute heart failure: redefining the cardiorenal interaction?

OBJECTIVES: We sought to study the individual and integrative role of amino-terminal pro-brain natriuretic peptide (NT-proBNP) and parameters of renal function for prognosis in heart failure.

BACKGROUND: Amino-terminal pro-BNP and renal impairment both predict death in patients with heart failure. Worsening of renal function in heart failure even defines the "cardiorenal syndrome."

METHODS: Seven hundred twenty subjects presenting with acute heart failure from 4 university-affiliated medical centers were dichotomized according to NT-proBNP concentration and baseline glomerular filtration rate. In addition, patients were divided according to changes in renal function. The primary end point was 60-day mortality.

RESULTS: The combination of a glomerular filtration rate (GFR) <60 ml/min/1.73 m2 with an NT-proBNP >4,647 pg/ml was the best predictor of 60-day mortality (odds ratio 3.46; 95% confidence interval 2.13 to 5.63). Among subjects with an NT-proBNP above the median, those with a GFR <60 ml/min/1.73 m2 or a creatinine rise > or =0.3 mg/dl had the worst prognosis, whereas in subjects with a NT-proBNP below the median, prognosis was not influenced by either impaired renal function at presentation or the development of renal impairment during admission.

CONCLUSIONS: The combination of NT-proBNP with measures of renal function better predicts short-term outcome in acute heart failure than either parameter alone. Among heart failure patients, the objective parameter of NT-proBNP seems more useful to delineate the "cardiorenal syndrome" than the previous criteria of a clinical diagnosis of heart failure.