Usefulness of B-type natriuretic peptide levels to predict left ventricular filling pressures in patients with body mass index >35, 31 to 35, and < or =30 kg/m2.

Noninvasive left ventricular (LV) pressure estimation in obese patients has not been well described. Simultaneous B-type natriuretic peptide (BNP) and echocardiographic Doppler examinations were performed in patients with dyspnea undergoing cardiac catheterization. Patients were divided into body mass index (BMI) >35 (markedly obese), 31 to 35 (obese), and < or =30 kg/m2 (nonobese). BNP levels and mitral early diastolic/tissue Doppler annular velocity (E/Ea) were compared with invasively measured LV end-diastolic and pre-atrial (pre-A) pressures. Seventy-two patients were studied. Except for BMI, LV mass index, and LV diastolic dimension, there were no significant differences in baseline, echocardiographic Doppler, or hemodynamic characteristics among the groups. However, BNP was significantly lower in markedly obese compared with obese and nonobese patients (116 +/- 187 vs 241 +/- 674 and 277 +/- 352 pg/ml, respectively; p = 0.03). BNP did not correlate with LV pre-A pressure in markedly obese patients (R = 0.13, p = 0.47), whereas BNP significantly correlated with this variable in the obese (R = 0.64) and nonobese (R = 0.58) groups. Mitral E/Ea significantly correlated with LV pre-A and LV end-diastolic pressures in all BMI groups. In markedly obese patients with dyspnea, BNP did not correlate with invasively measured LV filling pressure, whereas this correlated in obese and nonobese patients. However, mitral E/Ea significantly correlated with LV filling pressures in all BMI groups. In conclusion, BNP is not recommended for LV filling pressure estimation in ambulatory patients with dyspnea with BMI >35 kg/m2.