Background: The aim of the study was to assess the QTc interval and the dispersion of QT interval (dQT) in neonates with cardiac arrhythmias.
Material and methods: The study group consisted of 109 neonates with arrhythmias, divided into three groups according to ECG result: group I - 56 babies with premature beats, group II - 35 with bradycardia (heart rate below 80/min) and group III - 18 with tachyarrhythmia (heart rate above 180/min). The control group consisted of 35 healthy neonates.
Results: QTc in the neonates with arrhythmias was calculated from 0.280 s to 0.474 s, with a mean of 0.39 s. In 8 babies it was longer than 0.44 s. The dispersion of QT interval ranged from 10 ms to 80 ms, with a mean of 31 ms. In the control group QTc ranged from 0.324 to 0.432, with a mean of 0.382 s, and dQT from 10 ms to 30 ms, with a mean of 19 ms. The neonates with arrhythmias had significantly longer (p < 0.05) mean values of QTc and dQT compared with the control group. QTc and dQT were also significantly (p < 0.05) longer in the neonates with myocarditis. At the time of discharge from hospital, when the children were aged nearly one month, only 14% had cardiac arrhythmias. After one year follow-up arrhythmias were detected in 8% of them and the mean dispersion of QT was significantly lower (p < 0.05) at this time.
Conclusions: Cardiac arrhythmias in neonates are fairly benign and may disappear during the neonatal period. Greater values of the dispersion of the QT interval in the neonates can be a predisposing factor for arrhythmia. The neonates with myocarditis had greater values of QTc and the dispersion of QT. The neonates with myocarditis had increased values of QTc and QT dispersion.