Abstracts

Rationale: SUDEP (Sudden Unexpected Death in Epilepsy) is thought to occur as a consequence of peri-ictal lethal cardiac arrhythmias such as Torsades de Pointes. In this study, our objective was to identify how common ECG variables were altered in patients with recurrent epileptic seizures. Previous attempts at answering this question have produced inconsistent results, and have compared epilepsy patients to healthy controls, an approach that does not control for exposure to medications that may themselves alter ECG variables. Methods: After obtaining IRB approval, we performed a retrospective chart review of patients admitted to the BIDMC Epilepsy Monitoring Unit in the past 2 years. We excluded patients younger than 18 or over 65 years of age, implanted with a cardiac pacemaker, displaying significant electrolyte abnormalities on admission, or who were febrile, and/or taking medications known to alter QT intervals (other than antidepressant and antipsychotic medications). Based on EEG telemetry reports, we identified patients with DEFINITE EPILEPSY / DE (those with a clinical history consistent with recurrent unprovoked seizures, at least one electroclinical seizure and interictal epileptiform discharges) and NONEPILEPTIC SEIZURES / NES (those with EEG proven non-epileptic events). In subgroup analysis, we divided DE patients into those with primary generalized epilepsy and localization-related epilepsy, and further subdivided the latter, into those with seizures arising from the left or right hemisphere. Hodges formula was used to calculate the rate corrected QT (QTc). Results: DE (n=51) and NES (n=24) groups were matched in age (~40yo), sex (~40% male), antidepressant (~40%) and antipsychotic use (~15%). The average total number of antiepileptic medications taken at the time of admission was only marginally greater in DE patients (2.2 versus 1.4). DE patients had a larger QTc interval and displayed a more leftward axis deviation, while displaying similar PR intervals and ventricular rates. Preliminary subgroup analysis has revealed no differences between patients with primary generalized and localization-related epilepsy, and between left- and right-sided seizures. QTc intervals were significantly greater in women and directly proportional to age. Conclusions: Compared to patients with nonepileptic seizures, patients with recurrent epileptic seizures displayed a greater QTc interval and leftward axis deviation, suggesting a predisposition towards cardiac arrhythmias associated with early repolarization. We continue to build on our analysis' sample size to explore how specific forms of adult epilepsy may be associated with such ECG changes, and perhaps confer an increased risk for SUDEP. These data validate this experimental approach as being able to isolate clinical features that are uniquely associated with epileptic seizures and addresses certain confounding variables such as medication exposure. Overall, these data may provide insights into the bidirectional links between epilepsy and cardiac arrhythmias.