Vagus nerve stimulation reduces cardiac electrical instability assessed by quantitative T‐wave alternans analysis in patients with drug‐resistant focal epilepsy

Summary Objective The cardiac component of risk for sudden unexpected death in epilepsy (SUDEP) and alterations in cardiac risk by vagus nerve stimulation (VNS) are not well understood. We determined changes in T‐wave alternans (TWA), a proven noninvasive marker of risk for sudden cardiac death in p...

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Bibliographic Details
Published in:Epilepsia (Copenhagen) 2014-12, Vol.55 (12), p.1996-2002
Main Authors: Schomer, Andrew C., Nearing, Bruce D., Schachter, Steven C., Verrier, Richard L.
Format: Article
Language:English
Subjects:
Adult
Arrhythmias, Cardiac - etiology
Arrhythmias, Cardiac - therapy
Biophysics
Electrocardiography, Ambulatory
Epilepsies, Partial - complications
Epilepsies, Partial - physiopathology
Epilepsies, Partial - therapy
Female
Heart Rate - physiology
Heart rate variability
Humans
Male
Middle Aged
Monitoring, Physiologic
Sudden unexpected death in epilepsy
T‐wave alternans
Vagus nerve stimulation
Vagus Nerve Stimulation - methods
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Summary:Summary Objective The cardiac component of risk for sudden unexpected death in epilepsy (SUDEP) and alterations in cardiac risk by vagus nerve stimulation (VNS) are not well understood. We determined changes in T‐wave alternans (TWA), a proven noninvasive marker of risk for sudden cardiac death in patients with cardiovascular disease, and heart rate variability (HRV), an indicator of autonomic function, in association with VNS in patients with drug‐resistant focal epilepsy. Methods Ambulatory 24‐h electrocardiograms (N = 9: ages 29–63, six males) were analyzed. Results Mean TWA during the interictal period was 37 ± 3.1 μV (mean ± SEM) in lead V1 for nine patients monitored following implantation of the VNS system (n = 7) or battery change (n = 2). Of these, six patients also monitored prior to implantation (n = 5) or battery change (n = 1) showed abnormally high TWA levels pre‐VNS (60.0 ± 4.3 μV), which were significantly reduced by 24.3 μV (to 35.7 ± 4.8 μV, p = 0.02) after VNS settings were adjusted for desired clinical response. TWA in four (67%) of the six patients was reduced in association with VNS to levels below the 47‐μV cut point of abnormality. The decrease in TWA was correlated with VNS intensity (r = 0.88, p 
ISSN:0013-9580
1528-1167
DOI:10.1111/epi.12855