Interaction of Body Mass Index on the Association Between N‐Terminal‐Pro‐b‐Type Natriuretic Peptide and Morbidity and Mortality in Patients With Acute Heart Failure: Findings From ASCEND‐HF (Acute Study of Clinical Effectiveness of Nesiritide in Decompensated Heart Failure)

Abstract

Background Higher body mass index ( BMI ) is associated with lower circulating levels of N‐terminal‐pro‐b‐type natriuretic peptide ( NT ‐pro BNP ). The Interaction between BMI and NT ‐pro BNP with respect to clinical outcomes is not well characterized in patients with acute heart failure. Methods and Results A total of 686 patients from the biomarker substudy of the ASCEND ‐ HF (Acute Study of Clinical Effectiveness of Nesiritide in Decompensated HF ) clinical trial with documented NT ‐pro BNP levels at baseline were included in the present analysis. Patients were classified by the World Health Organization obesity classification (nonobese: BMI <30 kg/m 2 , Class I obesity: BMI 30–34.9 kg/m 2 , Class II obesity BMI 35–39.9 kg/m 2 , and Class III obesity BMI ≥40 kg/m 2 ). We assessed baseline characteristics and 30‐ and 180‐day outcomes by BMI class and explored the interaction between BMI and NT ‐pro BNP for these outcomes. Study participants had a median age of 67 years (55, 78) and 71% were female. NT ‐pro BNP levels were inversely correlated with BMI ( P <0.001). Higher NT ‐pro BNP levels were associated with higher 180‐day mortality (adjusted hazard ratio for each doubling of NT ‐pro BNP, 1.40; 95% confidence interval, 1.16, 1.71; P <0.001), but not 30‐day outcomes. The effect of NT ‐pro BNP on 180‐day death was not modified by BMI class (interaction P =0.24). Conclusions The prognostic value of NT ‐pro BNP was not modified by BMI in this acute heart failure population. NT ‐pro BNP remains a useful prognostic indicator of long‐term mortality in acute heart failure even in the obese patient. Clinical Trial Registration URL: http://www.clinicaltrials.gov . Unique identifier: NCT00475852.