QT dispersion in uncomplicated human obesity

Objective: Because obese patients generally may be prone to ventricular arr hythmias, this study was designed to measure the interval between Q- and T- waves of the electrocardiogram (QT) interval dispersion (QTD) in uncomplica ted overweight and obese patients. QTD is an electrocardiographic parameter whose prolongation is thought to be predictive of the possibility of sudde n death caused by ventricular arrhythmias. To better evaluate the associati on between obesity per se and QTD, the study population was intentionally s elected 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 ele ctrocardiogram) was measured manually in 54 obese patients (Group A: mean b ody mass index [BMI] of 38.1 +/- 0.9 kg/m(2) [SEM], 15 males and 39 females ), 35 overweight patients (Group B: mean BMI of 27.3 +/- 0.2 kg/m(2), 10 ma les and 25 females), and 57 normal weight healthy control subjects (Group C : mean BMI of 21.9 +/- 0.2 kg/m(2), 17 males and 40 females). The obese and overweight patients had no heart disease, hypertension, diabetes, or impai red glucose tolerance and did not have any hormonal, hepatic, renal or elec trolyte disorders. The study subjects were matched in terms of age (mean ag e 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 signif icant. The QTc intervals of Group A and Group B were similar to that of Gro up 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 bet ween QTD and QTc (r = 0.24, p < 0.005). Using multivariate stepwise regress ion 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 overweigh t subjects is comparable with that in age- and sex-matched normal weight he althy controls. In this study population, no association was found between QTD and anthropometric parameters reflecting body fat distribution.