In obesity, changes in the heart structure can be partially explained by the increase of total blood volume leading to volume overload, hypertension, left ventricular hypertrophy (LVH), and/or left ventricular dysfunction (LVD). Although patients with LVH have improved survival rates when medicated in the early stages of the disease, diagnosis may be difficult. Aminoterminal pro-brain natriuretic peptide (NT-proBNP), secreted from the left cardiac ventricle as a response to overload and ventricular damage, correlates with echocardiographic results. Therefore, the introduction of a serum assay that provides accurate information on the cardiac status of a patient may be useful. Because of the superiority of bariatric surgery, including laparoscopic adjustable gastric banding (LAGB), for the reduction of comorbidities, the researchers evaluated the effect of weight loss on NT-proBNP levels.

Thirty-four patients were enrolled (5 men, 29 women; mean age 40.65 [+ or -] 9.86 years) when they were referred to the Outpatient Obesity Department for surgery (LAGB group). All patients underwent LAGB (Lap-Band, BioEnterics, Carpinteria, CA). A healthy, non-obese, age- and sex-matched group of 34 participants was recruited from the hospital staff. All enrolled subjects were examined at the beginning of the study period, and the LAGB group again after a follow-up period of 12.13 [+ or -] 4.7 months. Blood samples were gathered after a 12-hour fast and a 10-minute rest in a lying position.

The cumulative weight loss in the LAGB group was 18.37 kg for the mean study period of 12 months. Subjects with LAGB weighed 127.3 [+ or -] 18.41 kg before and 107.75 [+ or -] 17.45 kg after surgery, which resulted in a reduction of BMI from 43.22 [+ or -] 3.42 kg/[m.sup.2] to 37.08 [+ or -] 5.86 kg/[m.sup.2] and a percentage of excess weight loss of 31.81 [+ or -] 18.51%. Systolic and diastolic blood pressure were lowered significantly after LAGB, but was still significantly higher after surgery when compared with controls. Plasma NT-proBNP concentration was significantly higher before LAGB than in normal-weight subjects. At 12 months post-LAGB, NT-proBNP concentration decreased significantly. Compared with normal weight subjects, NT-proBNP levels still remained significantly elevated in the LAGB group.

This study demonstrated elevated levels of NT-proBNP in morbidly obese patients and its decrease as an effect of significant weight reduction after LAGB. Recently, BNP and NT-proBNP have received major attention as cardiovascular markers because these peptides are secreted in cases of volume overload and increased ventricular wall tension. Because the morbidly obese subjects in the present study were still moderately overweight at the end of the study, NT-proBNP levels remained significantly higher compared with lean subjects. The extent of weight loss might contribute to the reduction of NT-proBNP because changes in NT-proBNP levels were significantly lower in the group of poor responders than in the group with greater weight loss. Therefore, in obesity, NT-proBNP might be useful as a routine screening method for identifying left ventricular hypertrophy and/or left ventricular dysfunction.