B-type natriuretic peptide levels in obese patients with advanced heart failure

OBJECTIVES This study aimed to examine the influence of obesity on the predictive value of the B-type natriuretic peptide (BNP) assay in heart failure (HF). BACKGROUND Recent studies show that obesity, or elevated body mass index (BMI), is associated with lower circulating levels of BNP both in the general population and in patients with HF. METHODS We analyzed data from 316 systolic HF (left ventricular ejection fraction [LVEF] <= 40%) patients [age, 53 +/- 13 years; mean LVEF, 24 +/- 7%; 48% ischemic] followed up at a university HF center. Patients were divided into categories of BMI: lean (BMI <25 kg/m(2)), overweight (BMI = 25 to 29.9 kg/m(2)), and. obese (BMI >= 30 kg/m(2)). RESULTS The BNP levels were significantly lower in overweight and obese compared with lean patients (p = 0.0001); median BNP (interquartile range) for the lean (n = 131), overweight (n = 99), and obese (n = 86) groups was 747 (272 to 1,300), 380 (143 to 856), and 332 (118 to 617) pg/ml, respectively. In each BMI category, elevated BNP was significantly associated with worse symptoms and higher pulmonary capillary wedge pressure. Higher BNP was also a significant independent predictor of survival independent of BMI. Optimal BNP cutoff for prediction of death or urgent transplant in lean, overweight, and obese HF patients was 590, 471, and 342 pg/ml, respectively. CONCLUSIONS Although BNP levels are relatively lower in overweight and obese HF patients, BNP predicts worse symptoms, impaired hemodynamics, and higher mortality at all levels of BMI.