Key result
Early post-convulsive ECGs in children showed a transiently higher rate of QTc prolongation (>440 ms) compared to follow-up ECGs 1-9 days later (23.3% vs 3.3%, p=0.0003).
Why the study?
Does a recent seizure cause transient prolongation of the QT interval in children?
Observational (n=60)
Does a recent seizure cause transient prolongation of the QT interval in children?
Absolute Event Rate: 23.3% vs 3.3%
p-value: p=0.0003
Slight to moderate post-convulsive prolongation of the QT interval is a common but transient finding in pediatric patients, which should be differentiated from congenital long QT syndrome.
Transient post-convulsive QTc prolongation warrants ECG caution in pediatric seizure evaluation; leaves open its arrhythmic significance.
AIM: An important differential diagnosis of seizures in childhood is the long QT syndrome. Childhood epilepsy occurs about 400 times more often than long QT syndrome. We had observed children with slight post-convulsive prolongation of QT time more often than the reported incidence of long QT syndrome. We therefore conducted a prospective study to define the characteristics of post-convulsive prolongation of QT time in children. METHODS: We investigated 30 consecutive infants and children (3 mo to 14 y) within 2 h after seizures. A follow-up ECG was obtained 1-9 d later. We also obtained ECGs from 30 healthy age- and gender-matched controls. We calculated the QT interval corrected for heart rate (QTc) by Bazett's formula in leads II, V5, V6, QT dispersion and the number of notched T waves. RESULTS: We found a QTc interval of more than 440 ms in one or more leads in the first ECG in seven of 30 infants and children compared to 1 of 30 in the follow-up ECG (p=0.0003) and two of 30 in the healthy controls (p=0.14). Average QTc was higher for all leads in the first ECG. This was statistically significant in leads II (414 vs 402 ms, p=0.008), V5 (416 vs 404 ms, p=0.002) and V6 (415 vs 399 ms, p=0.001). Compared to healthy controls, QT dispersion was slightly larger in the early post-convulsive ECG (36 vs 31 ms, p=0.03). Notched T waves occurred more frequently in the early compared to the late post-convulsive ECGs (p=0.009). CONCLUSION: Slight to moderate post-convulsive prolongation of the QT interval is not rare but transient in paediatric patients.
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Kändler et al. (2005) conducted an observational in Seizures (n=60). Recent seizure (within 2 hours) vs. Follow-up (1-9 days later) and healthy controls was evaluated on QTc interval > 440 ms in one or more leads (p=0.0003). Early post-convulsive ECGs in children showed a transiently higher rate of QTc prolongation (>440 ms) compared to follow-up ECGs 1-9 days later (23.3% vs 3.3%, p=0.0003).
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