Effect of Obesity on Ventricular Repolarization in Children

Obesity is known to be a risk factor of cardiac death, associated above all with cardiac arrhythmias. Delayed cardiac repolarization leading to the prolongation of the QT interval is a well recognized precursor of arrhythmias. The QT interval dispersion (QTD) and corrected QT interval dispersion (QTcD) reflect inhomogeneity of repolarization, and are measurable indices of ventricular arrhythmia risk. The aim of this study was to asses QT, QTc, QTD, and QTcD values in obese children, and find out whether repolarization abnormalities begin in childhood. Thirty-four obese children (6-16 years, mean 10,7±2,5 years) were included in the study. Obesity was defined according to the body mass index (BMI). Sixty control patients (7-15,5 years, mean 10,6±2,4 years) were matched in age and gender with the obese patients. A 12-lead conventional electrocardiogram was performed in all children. A blood sample was obtained for measuring hemoglobin and of concentrations plasma electrolytes. Hemoglobin and electrolyte levels showed no statistically significant difference between patients and controls. QT and QTc intervals were similar in both groups (p>0,05), but QTD and QTcD values were significantly higher in obese children than in controls (p<0,001) (patients QTD=51±18 ms, QTcD=72±24 ms; controls; QTD=40±10 ms, QTcD=48±10 ms). There was no correlation between BMI values and the QT intervals. Our findings suggest that, increased QTD and QTcD in obese children indicate ventricular repolarization abnormalities, and that these changes start in the childhood period of obesity.