QTcmin, QTcmax, and QTcd in the electrocardiogram may be used to distinguish children's vasovagal syncope (VVS) from epilepsy, says an article published in the Italian Journal of Pediatrics.
Transient loss of consciousness (TLOC) is a brief loss of consciousness that occurs spontaneously and is followed by a full recovery. The electrocardiogram, a common testing method in clinics, can reveal alterations in autonomic nerve function. The QT interval, which is controlled by the autonomic nervous system, is the total amount of time that a cardiomyocyte depolarizes and repolarizes. Both vasovagal syncope and epilepsy cause momentary unconsciousness and might be challenging to distinguish from one another. In order to better understand the role of QT interval in the distinction between VVS and epilepsy in children, Xin Wang and colleagues undertook this study.

A total of 131 kids who experienced a brief loss of consciousness without apparent cause were chosen. The average age of the 56 children with VVS (VVS group), 37 boys and 19 females, is 9.88 ± 2.55 years old. There are 57 epileptic children (epilepsy group), 36 of them male and 21 of them female, with an average age of 8.96 ± 2.67 years. The 60 healthy individuals (control group) were also analyzed for age and sex at the same time. Three groups' QT intervals on 12-lead electrocardiograms were measured and statistically evaluated using SPSS 24.0.
The key findings of this study were:
1. QTcmax, QTcmin, and QTcd were substantially longer in the VVS group compared to the control group (P 0.05), QTmax and QTmin were significantly shorter in the VVS group (P 0.05), and QTd did not change significantly between the two groups (P > 0.05).
2. The epilepsy group's QTmax and QTmin were substantially shorter (P 0.05), while the two groups' QTd, QTcmax, QTcmin, and QTcd did not vary significantly (P > 0.05). There were no significant changes in QTd, QTmax, or QTmin between the two groups (P > 0.05), however the VVS group's QTcmax, QTcmin, and QTcd were considerably longer than those of the epilepsy group (P 0.05).
3. The specificity and sensitivity of detecting VVS were 62.5% and 77.19%, 82.14% and 50.88%, 82.14% and 38.60%, respectively, when QTcmax > 479.84 ms, QTcmin > 398.90 ms, and QTcd > 53.56 ms.
In conclusion, since heart rate may have an impact on QTd, QTmax, and QTmin, there is no discernible difference between the two groups (P > 0.05). Thus, QT interval markers have some therapeutic relevance in distinguishing between VVS and epilepsy in young patients.
Reference:
Wang, X., Wang, S., Xiao, H., Zou, R., Cai, H., Liu, L., Li, F., Wang, Y., Xu, Y., & Wang, C. (2022). The value of QT interval in differentiating vasovagal syncope from epilepsy in children. In Italian Journal of Pediatrics (Vol. 48, Issue 1). Springer Science and Business Media LLC. https://doi.org/10.1186/s13052-022-01388-2