Lengthening of corrected QT during epileptic seizures.
OBJECTIVE
To measure the corrected QT cardiac repolarization time before and during epileptic seizures.


METHODS
Thirty-nine video-EEG/ECG/SAO(2) (electroencephalography/electrocardiography/oxygen saturation) telemetry patients were included in this prospective study. Epileptic seizures were identified both clinically and electrographically. RR intervals and associated QT intervals were measured 5 min prior to the onset of the identified seizure. Consecutive RR and associated QT intervals were then measured from the seizure onset until the seizure had ended and the EEG had resumed its preseizure trace. Averaged RR and QT intervals over nine consecutive beats were applied to Bazett's, Hodge's, Fridericia's, and Framingham's formulas to compare the corrected QT values before and during the seizures.


RESULTS
A total of 156 seizures had corrected QT analysis performed. Nine generalized tonic-clonic seizures (5 patients), 34 absences (6 patients), 12 tonic seizures (6 patients), 27 temporal lobe seizures (14 patients), 58 frontal lobe seizures (4 patients), and 16 subclinical seizures (4 patients). All formulae reported a statistically significant difference in corrected QT (p < 0.001) during total seizure data compared to total preseizure values. According to Bazett's formula, 21 seizures (nine patients) transiently increased their corrected QT beyond normal limits, with a maximum corrected QT of 512 ms during a right temporal lobe seizure.


CONCLUSIONS
Significant lengthening of corrected QT cardiac repolarization time occurred during some epileptic seizures in this study. Prolonged corrected QT may have a role in sudden unexplained death in epilepsy (SUDEP).
Brotherstone
Ruth
R
Department of Clinical Neurophysiology, Western General Hospital, Edinburgh, United Kingdom. ruth.brotherstone@luht.scot.nhs.uk
Blackhall
Bethia
B
McLellan
Ailsa
A
D000293:Adolescent; D000328:Adult; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D016757:Death, Sudden, Cardiac; D004562:Electrocardiography / Q000379:methods / Q000706:statistics & numerical data*; D004569:Electroencephalography / Q000706:statistics & numerical data; D004828:Epilepsies, Partial / Q000175:diagnosis / Q000453:epidemiology; D004827:Epilepsy / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care; D011446:Prospective Studies; D013686:Telemetry; D014743:Videotape Recording