The basic manifestations of dystrophic changes in heart of children suffering form diabetes mellitus type 1 (DM1) are disturbances of repolarization and depolarization processes, including QT and QTc intervals prolongation. Research objective: to evaluate indices of QT and QTc in children with DM1, to reveal interrelation of the observed changes with the duration of disease, age, sex, levels of cholesterol (CH) and glycemie, BMI, blood pressure, pulse rate.
Materials and methods: QT and QTc were evaluated on ECG in 164 children with DM1 (middle age 13.4±0.92 years, duration of disease 5.85±0.89 years) and in 60 sex- and age-matched healthy children. Level of HbA1c in children with DM1 made up 9.65±0.51% (N to 7.5%; P<0.0005).
Results: QT and QT are increased in children with DM1 in comparison with control group (363.51±8.5 ms and 421.13±12.5 ms, 352.97±15.1 ms and 392.73±13.0 ms respectively, P<0.0001). Values of QTc in girls with DM1 are higher than that values in boys (425.36±14.8 ms versus 416.24±14.8 ms, P<0.002). 21.59% of girls and 15.79% of boys with DM1 have QTc>440 ms. At the same time values of fructozamine level are higher in boys than in girls (412.88±11.35 and 377.66±8.76 mkmol/l respectively, P<0.001). The difference in pulse rate between girls and boys is insignificant for the group studied. Connection of QTc with age (r=0.334, P<0.0003) and level of HbA1c (r=0.37, P<0.0001) was established. Feedback connection of QT with pulse rate was revealed (r=−0.48, P<0.0001). Reliable correlation between QTc and values of BMI, level of CH, duration of the disease and values of systolic and diastolic blood pressure was not established.
Conclusions: The increase of QT and QTc is noticed in children with DM1. Age, level of glycemie, pulse rate and sex are the factors defining values of QTc.