Right ventricular performance in severe obesity. Effect of weight loss

Background: The effects of severe obesity on right ventricular function in the absence of associated cardiopulmonary disease are not well known. Right myocardial performance index (R-MPI) is an echocardiographic index to non-invasively assess the right ventricular function. The aim of our study was to assess R-MPI in individuals with severe but uncomplicated obesity before and after a significant weight loss induced by bariatric surgery. Patients and methods: Fifteen obese females (OB) without cardiovascular and pulmonary diseases were examined. In all subjects, R-MPI was calculated by Doppler echocardiography as the sum of isovolumetric contraction time and isovolumetric relaxation time divided by ejection time. Furthermore, pulmonary function test (PFT) and 6-min walking test (6mWT) were performed. Ten healthy subjects with normal weight (HS) were also evaluated as controls. R-MPI, PFT and 6mWT were also re-evaluated one year later in 12 obese subjects treated with gastric banding after a consistent weight loss (> 20%). Results: A prolongation of R-MPI was found in OB before bariatric surgery in comparison to the HS (0.47 +/- 0.04 and 0.29 +/- 0.05, respectively; P < 0.001). R-MPI significantly improved in OB 12 months after surgery (0.32 +/- 0.03) and was no longer different from HS. R-MPI positively correlated to body mass index (BMI). A significant association was found between the reduction of BMI after bariatric surgery and the distance walked during the 6mWT. Conclusions: These results show a right ventricular dysfunction in severe uncomplicated obesity, associated with an impaired functional capacity which recovers after consistent weight loss.