Increased QT dispersion in epileptic children

Akalin F, Tirtir A, and Yilmaz Y (2003) Increased QT dispersion in epileptic children. Acta 75 Paediatr 92:8 916–20

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Abstract: AIM: Epilepsy is a common paroxysmal disorder in childhood. Tachyarrhythmia, bradyarrhythmia, asystole, atrioventricular block, ventricular fibrillation or sudden death may occur during seizures. Mutations of ion-channel coding genes are found in patients with idiopathic or cryptogenic epilepsy. The ion channels also play a role in arrhythmogenesis. QT dispersion is a non-invasive method for assessment of regional repolarization differences within the myocardial tissue. This study investigated QT and QTc dispersion (QTcd) and the risk of dysrhythmia in epileptic children. METHODS: The first group included 28 patients with newly diagnosed epilepsy and not taking antiepileptic treatment (range 10 mo to 15 y, mean +/- SD 6.86 +/- 3.92 y), the second group included 34 patients taking antiepileptic treatment (range 1-14 y, mean +/- SD 7.51 +/- 3.68 y) and the control group included 52 healthy children (range 4 mo to 15 y, mean +/- SD 6.94 +/- 3.92 y). Twelve-lead ECGs were obtained and heart rate, RR interval, P wave amplitude and duration, PR interval, QRS duration, QRS axis and QT intervals were measured, and QTc, QTd, QTcd were calculated in all subjects. The measurements were repeated in the first group under antiepileptic treatment. RESULTS:While no significant difference in terms of heart rate, RR interval, P wave amplitude and duration, PR interval, QRS duration, QRS axis, QT intervals or QTc intervals was found, QTd and QTcd values were significantly increased in epileptic children compared with the control group. QTd was 58.1 +/- 13.4 ms and 35.9 +/- 9.3 ms and QTcd was 91.0 +/- 22.9 and 68.6 +/- 18.0ms in patients and controls, respectively. Antiepileptic treatment did not affect QT dispersion. CONCLUSION: QT dispersion is increased in epileptic children. Further investigation is needed to reveal the pathogenesis of myocardial repolarization abnormalities in epileptic patients.

Keywords: Dysrhythmia, epilepsy, ion channels, QT dispersion, ventricular repolarization

Comments and Context

• Study of patients newly diagnosed with epilepsy and others already taking medication, both in comparison with children free of epilepsy. QT dispersion, a measure of the variability of repolarization of myocardium across different regions of the ventricles (Higham and Campbell), was increased in children with epilepsy. This suggests that the presumptive ion channel abnormalities underlying idiopathic epilepsy may also affect the function of the heart (see Donahue et al.). This finding could have implications for cardiac dysfunction in SUDEP. As AEDs could also affect heart function, another important finding of this study was that QT dispersion was no different in the two groups of children with epilepsy, and also no different in the newly diagnosed patients before versus after starting medication, indicating that AEDs have little effect on this heart function parameter. The study included 62 patients with epilepsy and 52 epilepsy-free children. AEDs used in the newly-prescribed group were valproate, CBZ and phenobarbitol. Relative differences in QT intervals between EKG leads could be influenced by the shorter baseline QT intervals seen in epilepsy patients (Teh et al.). For further discussion of QT intervals see annotation at Aurlien et al. Also of note, an effect of CBZ on QT dispersion has been reported (Spina et al.). Measurements of QT in this paper were done manually by a single observer and it is not clear whether he or she was blinded to the group status of patients when measurements were made.