Obesity influences B-type natriuretic peptide levels in patients with decompensated heart failure

Abstract

Background: It has been described that adipose cells express the clearance receptor for natriuretic peptides. Therefore, obesity may be responsible, at least in part, for low natriuretic peptide activity observed in some patients with heart failure (HF). Objectives: We sought to describe the relationship between obesity and B-type natriuretic peptide (BNP) levels in patients who present to the emergency department with HF. Methods: From April 2001 through August 2003, 260 patients presented to an emergency department complaining of dyspnea and were included in a study which assessed the utility of BNP measurement using a point of care assay in the diagnosis and prognosis of HF. Among these patients, 124 (48%) had a final diagnosis of HF as the cause of dyspnea and were included in this analysis. Mean age was 72±28 years and 61 (49.2%) were male. All patients were NYHA class III or IV. We assessed the relationship between body mass index (BMI) and BNP values, controlling for confounding factors. According to BNP levels, the patients were classified into three categories: less than 500 pg/mL, 500 to 1,000 pg/mL, and above 1,000 pg/mL. Results: Mean BMI was 28.3±4.6 Kg/m2 and 42 (34%) were obese (IMC>30 Kg/m2). Despite similar age, NYHA class, left ventricle ejection fraction, and serum creatinine, BNP levels were significantly lower in obese patients as compared to non-obese (806±212 vs 1,126±320 pg/mL, p<0.0001). Independent predictors of lower BNP levels (< 500 pg/mL) were age<70 years, (p=0.0002), creatinine<1.3 mg/dL (p=0.0034) and IMC>30 Kg/m2 (p=0.0042). Conclusion: This study suggests that obesity influences BNP levels in patients with decompensated HF.