The relationship between Tonic-Clonic sizures in children and increased time of ventricular repolarization

Background: Long QT syndrome (LQTS) is a disorder in which electrical cardiac ventricular repolarization is impaired. It results in an increased risk of an irregular heartbeat which can result in palpitations, fainting, drowning, or sudden death. Long QT Syndrome may present as tonic-clonic seizure or a seizure-like disorder. By taking a superficial electrocardiogram (ECG) and proper diagnosis, Sudden death, one of the most important complications of Long QT syndrome can be easily prevented. Methods: This is a prospective case-control study that was conducted in the emergency department of Taleghani Children's Hospital of Gorgan University during 2017. Four hundred and eighty subjects in three groups (two cases and one control groups), were included in this study. These comprised as patients with afebrile convulsion (n: 160), patients with seizures associated with fever (n: 160), and the control group (patients who have been hospitalized for any reason other than seizure (n: 160)). Those with severe cerebral palsy, acute meningitis, prolonged loss of consciousness, severe disturbances of electrolytes and those who were taking drugs that affect the QT interval were excluded. Once admitted with a primary diagnosis of seizure, a 12 leads superficial ECG was performed. Results:  In the group of patients with febrile convulsion, 123 children were Low probability Long QT syndrome, 33 cases were Intermediate and 4 were high probability Long QT syndrome. Probability of Long QT syndrome in children with afebrile seizures showed that 112 children were in Low probability Long QT syndrome, 42 children in Intermediate and 6 children in High probability Long QT syndrome group. Comparison of Probability of Long QT syndrome among the three evaluated groups showed that children with afebrile seizure (48 children) and subsequently children with febrile seizure (37 children) were more in Intermediate and High categories than others. Only 11 children in the control group were in the Intermediate and High groups. Chi-square test results showed a significant difference with P<0.001. Conclusion:  The results of this study show that in patients who present with seizure as the initial symptom, it is always mandatory to account Long QT syndrome into differential diagnosis. Doing a simple electrocardiogram makes it easy to distinguish two issues and prevent sudden death.