Effect of weight loss on ventricular repolarization in normotensive severely obese patients with and without heart...

Obesity has been reported to be associated with delayed ventricular repolarization. The purpose of this study was to assess ventricular repolarization in normotensive severely obese subjects with and without heart failure (HF) and to assess the effect of weight loss on ventricular repolarization in such patients.

Twenty-eight patients with and 39 patients without HF (body mass index ≥ 40 kg/m(2)) were studied before and after weight loss from bariatric surgery. Corrected QT interval (QTc) was measured on 12-lead electrocardiograms using Bazett's formula. QTc dispersion was calculated by subtracting the minimum from the maximum QTc on each 12-lead electrocardiogram. Electrocardiograms and transthoracic echocardiograms were performed preoperatively and at the nadir of postoperative weight loss.

Mean QTc and QTc dispersion were significantly longer/greater in subjects with HF than in those without HF (P < 0.0001). Weight loss produced significant reductions in mean QTc and QTc dispersion in both subgroups (P < 0.0001). Pre-weight loss left ventricular (LV) mass/height and presence or absence of HF independently predicted pre-weight loss QTc and QTc dispersion (P < 0.0001). Weight loss-induced decrease in LV mass/height independently predicted weight loss-induced decreases in QTc and QTc dispersion (P < 0.0001).

HF independently predicts QTc and QTc dispersion in normotensive severely obese patients. Decrease in the LV mass resulting from weight loss independently predicts reduction in QTc and QTc dispersion in such patients.