Natriuretic Peptides, Body Mass Index, and Clinical Outcomes in Heart Failure With Mildly Reduced or Preserved Ejection Fraction

BACKGROUND Natriuretic peptides are the primary biomarkers recommended in heart failure (HF) guidelines to risk stratify patients in clinical practice and serve as key eligibility criteria in contemporary clinical trials. However, threshold levels typically do not account for measures of adiposity, such as body mass index (BMI). OBJECTIVE To evaluate the association between N-terminal pro-B-type natriuretic peptide (NT-proBNP) with clinical outcomes in individuals with HF and mildly reduced or preserved ejection fraction (HFmrEF/HFpEF), stratified according to BMI. METHODS In this participant-level pooled analysis of 4 global, randomized, outcomes trials including adults with HFmrEF/HFpEF, the association between NT-proBNP and clinical outcomes (cardiovascular death or HF hospitalization, cardiovascular death, HF hospitalization, and all-cause death) was evaluated according to BMI as a continuous and categorical variable. RESULTS Among 14,750 participants (mean age, 72±9 years; 50% female; mean BMI, 30±6 kg/m2; median NT-proBNP, 836 pg/mL), higher baseline BMI was significantly and non-linearly associated with lower NT-proBNP levels. Over a median follow-up of 2.8 years, each doubling of baseline NT-proBNP was associated with a 40% higher covariate-adjusted rate of cardiovascular death or HF hospitalization (hazard ratio, 1.40; 95% CI, 1.36-1.43; P<0.001). However, this association appeared incrementally blunted with higher baseline BMI (Pinteraction=0.008). For the same absolute risk of cardiovascular death or HF hospitalization (5 events per 100 person-years), NT-proBNP levels in participants without atrial fibrillation were nearly 3-fold lower among those with BMI ≥35 kg/m2 (158 pg/mL) vs. <35 kg/m2 (450 pg/mL). At a contemporary NT-proBNP-based trial eligibility threshold, absolute risk of cardiovascular death or HF hospitalization ranged from 3.5 per 100 person-years among persons with BMI <30 kg/m2 to 7.3 per 100 person-years among those with BMI ≥40 kg/m2. CONCLUSIONS In this analysis, current NT-proBNP thresholds substantially underestimated the absolute risk of adverse HF outcomes among persons with higher BMI. These data question single fixed thresholds and instead suggest that lower NT-proBNP cutoffs may more appropriately risk stratify patients at higher BMI.