Prolonged QT dispersion in the infants of diabetic mothers

Myocardial hypertrophy and cardiac dysfunction frequently occur in newborns of diabetic mothers. The authors hypothesized that wall hypertrophy or disproportionate left ventricular wall thickness in newborns of diabetic mothers may affect both QT and QTc dispersion. This study aimed to assess whether left ventricular hypertrophy affects the QT variables of infants born to diabetic mothers. This prospective cross-sectional study was conducted with 47 consecutively selected neonates of gestational diabetic mothers and 30 healthy neonates born to healthy mothers. All the subjects were evaluated during the neonatal period. Electrocardiography with echocardiography was performed for the patients and the control subjects. The newborns of the diabetic mothers were classified according to septal thickness as group 1 (16 newborns with septal hypertrophy) or group 2 (31 newborns without septal hypertrophy). The study group consisted of three cohorts: groups 1, 2, and 3 (control group). Both QT and QTc dispersion were computed from a randomly selected beat as well as from an average beat derived from 12 beats included in a 10-s electrocardiography. A total of 16 infants (34%) had a septal thickness of 6 mm or greater. The left ventricular end-systolic diameter in group 1 was smaller (p = 0.0029) than in groups 2 and 3 (p = 0.003). The interventricular septal thickness at end diastole (IVSTd) and the left ventricular posterior wall thickness at end diastole in group 1 were higher than in of groups 2 and 3. The QT and QTc dispersion intervals were longer in group 1 than in groups 2 and 3 (p < 0.001), and a highly significant positive correlation was detected between IVSTd and QT dispersion (r = 0.514, p = 0.042). Elevated QT and QTc dispersions may be risk factors for the development of arrhythmias in newborns of diabetic mothers. These patients may critically need systematic cardiac screening.