BACKGROUND: The aim of this study was to characterize N-terminal pro-B-type natriuretic peptide (NT-proBNP) in terms of determinants of levels and of its prognostic and discriminatory role in heart failure with mid-range (HFmrEF) versus preserved (HFpEF) and reduced (HFrEF) ejection fraction.

METHODS AND RESULTS: In 9847 outpatients with HFpEF (n = 1811; 18%), HFmrEF (n = 2122; 22%) and HFrEF (n = 5914; 60%) enrolled in the Swedish Heart Failure Registry, median NT-proBNP levels were 1428, 1540, and 2288 pg/mL, respectively. Many determinants of NT-proBNP differed by ejection fraction, with atrial fibrillation (AF) more important in HFmrEF and HFpEF, diabetes and hypertension in HFmrEF, and age and body mass index in HFrEF and HFmrEF, whereas renal function, New York Heart Association functional class, heart rate, and anemia were similar. Hazard ratios for death and death/HF hospitalization for NT-proBNP above the median ranged from 1.48 to 2.00 and were greatest for HFmrEF and HFpEF. Areas under the receiver operating characteristic curve for death and death/HF hospitalization were greater in HFmrEF than in HFpEF and HFrEF and were reduced by AF in HFpEF and HFmrEF but not in HFrEF.

CONCLUSIONS: In HFpEF and especially HFmrEF, NT-proBNP was more prognostic and discriminatory, but also more affected by confounders such as AF. These data support the use of NT-proBNP for eligibility, enrichment, and surrogate end points in HFpEF and HFmrEF trials, and suggest that cutoff levels for eligibility should be carefully tailored to comorbidity.