QT Dispersion in Uncomplicated Human Obesity

Objective: Because obese patients generally may be prone to ventricular arrhythmias, this study was designed to measure the interval between Q- and T-waves of the electrocardiogram (QT) interval dispersion (QTD) in uncomplicated overweight and obese patients. QTD is an electrocardiographic parameter whose prolongation is thought to be predictive of the possibility of sudden death caused by ventricular arrhythmias. To better evaluate the association between obesity per se and QTD, the study population was intentionally selected because they were free of complications. Research Methods and Procedures: QTD (defined as the difference between the maximum and the minimum QT corrected interval [QTc] across the 12-lead electrocardiogram) was measured manually in 54 obese patients (Group A: mean body mass index [BMI] of 38.1 ± 0.9 kg/m2 [SEM], 15 males and 39 females), 35 overweight patients (Group B: mean BMI of 27.3 ± 0.2 kg/m2, 10 males and 25 females), and 57 normal weight healthy control subjects (Group C: mean BMI of 21.9 ± 0.2 kg/m2, 17 males and 40 females). The obese and overweight patients had no heart disease, hypertension, diabetes, or impaired glucose tolerance and did not have any hormonal, hepatic, renal or electrolyte disorders. The study subjects were matched in terms of age (mean age 38.4 ± 1.2 years) and sex. Results: The QTDs were comparable among the three groups: Group A, 56.4 ± 2.6 ms; Group B, 56.7 ± 2.1 ms; and Group C, 59.4 ± 2.1 ms; not significant. The QTc intervals of Group A and Group B were similar to that of Group C (411.8 ± 3.3, 407.2 ± 3.9, and 410.3 ± 3.9 ms, respectively [not significant]) and did not correlate with BMI. An association was found between QTD and QTc (r = 0.24, p < 0.005). Using multivariate stepwise regression analysis of the study population, QTD did not correlate with age, BMI, waist circumference, or abdominal sagittal diameter. Discussion: These data suggest that QTD in uncomplicated obese or overweight subjects is comparable with that in age- and sex-matched normal weight healthy controls. In this study population, no association was found between QTD and anthropometric parameters reflecting body fat distribution.