Abstract Details

Title Comparative Acute Impact of Focal and Generalized Tonic-clonic Seizures on Cardiac Electrical Instability in the Epilepsy Monitoring Unit

Topic Epilepsy/Clinical Neurophysiology (EEG)

Presentation(s) S13 - Epilepsy/Clinical Neurophysiology (EEG) 1 (2:36 PM-2:48 PM)

Poster/Presentation
Number 009

Objective

We compared the effects of acute generalized tonic-clonic, focal, and nonepileptic seizures on T-wave alternans (TWA), a marker of cardiac electrical instability linked to sudden cardiac death.

Background

Sudden cardiac arrest is 3-fold greater in patients with chronic epilepsy than in the general population. We hypothesized that because generalized tonic-clonic seizures (GTCS) are associated with greater disruption of autonomic function as compared with focal seizures and nonepileptic seizures, the ictal impact on cardiac electrical instability would be greatest during GTCS.

Design/Methods In 15 patients in the epilepsy monitoring unit, we analyzed the effect of acute seizures on heart rate and TWA.

Results Focal seizures (n=7 patients) provoked significant increases in TWA (from 2±0.5 to 30±3.3 µV ictally, p<0.0001) (Figure) but maximum TWA levels did not exceed the 47-µV cutpoint of abnormality in any patient. By comparison, GTCS (n=5 patients) resulted in more marked increases in TWA (from 2±0.3 to 70±6.1 µV, p<0.0001), which exceeded the 60-µV cutpoint of severe abnormality in every patient. Heart rate increases during GTCS (from 62±5.8 to 134±8.6 beats/min, an increase of 72±7.2 beats/min) were greater (p=0.014) than during focal seizures (from 70±5.2 to 118±6.3 beats/min, an increase of 48±2.6 beats/min). In 3 patients with nonepileptic seizures, TWA was only mildly elevated (from 2±0.3 to 28±6.3 µV). The associated increases in heart rate likely reflect the reciprocal increase in sympathetic activity and decrease in cardiac vagal tone, factors known to increase TWA.

Conclusions This is the first study to demonstrate that GTCS provoke highly significant ictal increases in TWA. Further, the levels observed have been associated with heightened risk for sudden cardiac death in other populations. By comparison, focal seizures induced moderate increases in TWA ictally, whereas effects on TWA during nonepileptic seizures were only mild despite concurrent heart rate increases.

Authors/Disclosures
Trudy Pang, MD (Beth Israel Deaconess Medical Center) PRESENTER	Dr. Pang has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Stratus an Alliance Company.
	No disclosure on file
	No disclosure on file
Steven C. Schachter, MD, FAAN	Dr. Schachter has received personal compensation in the range of $0-$499 for serving as a Consultant for Supernus Pharmaceuticals. Dr. Schachter has received personal compensation in the range of $50,000-$99,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Elsevier. Dr. Schachter has received intellectual property interests from a discovery or technology relating to health care. Dr. Schachter has received publishing royalties from a publication relating to health care. Dr. Schachter has received publishing royalties from a publication relating to health care.
	No disclosure on file

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