B-type natriuretic peptide and N-terminal pro B-type natriuretic peptide are depressed in obesity despite higher left ventricular end diastolic pressures

Background B-Type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are frequently used in diagnosing and monitoring patients with heart failure. Recent studies have demonstrated that concentrations of these pepticles are decreased in obese patients, but whether lower natriuretic pepticle concentrations are really due to different hemodynamics is unknown. The relationship between these markers and left ventricular end diastolic pressure (LVEDP) in obesity has not been elucidated. Methods We examined patients undergoing cardiac catheterization who had creatinine of < 2.0, no evidence of myocardial infarction or pulmonary embolism, and no cardiac transplant. Body mass index and LVEDP were determined, and BNP and NT-proBNP obtained at the start of each case. Obesity was defined as body mass index of >= 30 kg/m(2). Results Of 203 patients enrolled, 101 were obese. The groups were similar in respect to race, creatinine, cholesterol, and history of dyslipidemia and cardiomyopathy. The obese patients tended to be younger, were more likely to have diabetes and hypertension, and were less likely to have coronary artery disease. The obese patients had higher LVEDP but reduced BNP and NT-pro-BNP. The relationship between the natriuretic pepticles and LVEDP was poor, with r values of < 0.1. Conclusions Obese patients have reduced concentrations of BNP and NT-proBNP compared to nonobese patients despite having elevated LVEDP. This suggests that factors other than cardiac status impact on BNP and NT-proBNP concentrations. The poor relationship between natriuretic peptide concentrations and LVEDP also suggests that these concentrations should not be considered surrogates for cardiac filling pressures or volumes.