Background: Suppressed plasma B-type natriuretic peptide (BNP) levels have been reported in obese individuals with heart failure (HF). However, the precise mechanism and significance of this relationship in the clinical setting of HF are unknown. Recently, we reported a close association between BNP levels and left ventricular end-diastolic wall stress (EDWS) as the underlying mechanism of BNP secretion; therefore, we investigated the relationship between BMI and plasma BNP levels in HF while adjusting for EDWS.
Methods and results: In 245 consecutive patients who presented with HF, we measured plasma BNP levels and performed echocardiography and cardiac catheterization. Meridional EDWS was calculated from echocardiographic and hemodynamic parameters. The body mass index (BMI) for the total population was 22.9 +/- 0.2 kg/m2; 21% were lean (BMI < 20) and 27% overweight and obese (BMI > or = 25). The correlation between plasma BNP and EDWS [r = 0.771 (P <.001)] was more robust than any other echocardiographic or hemodynamic parameter as well as any patient's characteristics. By a univariate analysis, BMI was inversely correlated with both BNP levels and EDWS (P <.001 in both). However, a multivariable regression analysis that took into account EDWS demonstrated a significant inverse association between BMI and BNP (P <.001).
Conclusion: The present study demonstrates that BMI determines the BNP level in a manner that is independent of the hemodynamic load in patients with HF. Overweight and obesity should be considered to be associated with the interindividual variability of plasma BNP levels in the diagnosis and management of HF patients.