Abstracts

Rationale: Children with familial long QT syndrome are predisposed to episodic ventricular arrhythmias, torsades de pointe, syncope and generalized seizures. Because long QT syndrome can manifest as a neurological disorder (syncope, seizures), many children receive a primary neurological neurological evaluation including a routine EEG. Our previous retrospective study suggested an increased incidence of prolonged QTc as read in the EEG of patients with syncope. The purpose of this study is to assess the accuracy of the EEG QTc reading when compared with the 12-lead EKG in children with syncope. Methods: The study was approved by the University Institutional Review Board. The EEG database of the Section of Neurology of our institution was searched to identify recordings of children with a history of syncope since January 2005. The results were cross-matched with the EKG database in the Section of Cardiology to identify patients who also had an EKG. The EEG QT and RR interval were measured digitally three times and the QTc was calculated as the QT interval divided by the square root of the RR interval (Bazett’s method). The average of the three sets of values was used for analysis. The EKG QTc was manually measured by an experienced cardiologist. The readings of the EKG were blind from the EEG results. The Abnormal QTc was defined as ≥ .450 in boys and ≥ .460 in girls. Pearson correlation was performed using SPSS. Results: A total of 42 children, 10 boys and 32 girls, between 5 and 17 years of age, with a history of syncope were included in the study. There was no significant correlation between QTc readings in the EEG and the EKG (r=0.04). Two boys with prolonged QTc on the EKG had normal QTc in the EEG and 2 girls and 1 boy with prolonged QTc in the EEG had normal QTc in the EKG. The time between the EEG and EKG recordings in the patients with a prolonged QTc in either test was less than 2 weeks. Conclusions: There was no correlation between the EEG and the EKG QTc readings. EEG failed to identify 2 patients with prolonged QTc in the EKG and overestimated the QTc in 3 patients who had normal QTc in the EKG. Contrary to our previous research, the present study suggests that interpretation of the QTc segment in the EEG is limited. Future studies with simultaneous EEG and EKG recording in a larger population are needed to validate these results.