PURPOSE: The effect of weight loss on ventricular repolarization in morbid obesity is unknown. The purpose of this study was to assess the effect of substantial weight loss on ventricular repolarization in normotensive morbidly obese subjects.
METHODS: The study population consisted of 39 patients (31 females, 7 males, mean age: 37 ± 8 years) who were free from organic heart disease not directly related to obesity based on clinical, electrocardiographic, radiographic and echocardiographic evaluation. Standard 12 lead electrocardiograms (paper speed: 25 mm/sec) and transthoracic echocardiograms were performed just prior to and following bariatric surgery at the nadir of weight loss. QTc was derived using Bazett’s formula and QT dispersion was calculated by subtracting the minimum QT interval from the maximum QT interval on the 12 lead electrocardiogram. Left ventricular (LV) mass was calculated using the formula of Devereux and Reichek.
RESULTS: Weight loss from 126% to 39% overweight produced significant reductions in mean QTc (from 428.5 ± 19.0 ms to 411.3 ± 13.4 ms, p < 0.001) and QT dispersion (from 44.1 ± 11.3 ms to 38.1± ms, p < 0.001). Change in QTc correlated positively and significantly with change in left ventricular mass/height index (r = 0.602, p < 0.001), systolic blood pressure (r = 0.440, p < 0.01), LV end - systolic wall stress (r = 0.377, p = 0.018) and LV internal dimension in diastole (r = 0.472, p = 0.002). Similarly, change in QT dispersion correlated positively and significantly with LV mass/height index (r = 0.623, p < 0.001), systolic blood pressure (r = 0.454), p < 0.004), LV end-systolic wall stress (r = 0.677, p < 0.001) and LV internal dimension in diastole (r = 0.447, p = 0.004).
CONCLUSION: Substantial weight loss produces significant reductions in QTc and QT dispersion. These changes are strongly associated with reductions in LV mass and the loading conditions that contribute to LV mass.
CLINICAL IMPLICATIONS: Substantial weight loss improves ventricular repolarization in morbidly obese persons possibly reducing arrhythmogenic risk.
DISCLOSURE: Rita Mukerji, No Financial Disclosure Information; No Product/Research Disclosure Information