Analysis of ventricular late potentials in signal-averaged ECG of people with epilepsy

Authors


Address correspondence to Dr. Konrad Rejdak, Department of Neurology, Medical University of Lublin, 8 Jaczewskiego Str., 20-954 Lublin, Poland. E-mail: krejdak@europe.com

Summary

Purpose:  There has been growing interest in cardiac disturbances in epilepsy patients and their etiologic role in the context of sudden death. Ventricular late potentials (VLPs) recorded on signal-averaged electrocardiography (SAECG) reflects delayed ventricular depolarization and identifies the structural or functional substrate for the ventricular tachycardia in the reentry mechanism. Therefore, abnormal SAECG poses the potential of identifying patients at increased risk of malignant ventricular arrhythmias and sudden cardiac death. The aim of this exploratory study was to screen epilepsy patients who were treated with established doses of antiepileptic drugs (AEDs) on the presence of VLPs.

Methods:  Forty-five consecutive patients with the diagnosis of epilepsy and 19 healthy volunteers, aged younger than 46 years, participated in the study. Exclusion criteria included symptoms or signs of diseases other than epilepsy, in particular relating to heart disease or medication influencing the cardiovascular system, as well as seizure reported by patients that occurred <3 days before the ECG examination. The electrocardiogram was recorded according to the standard protocol. The seizure frequency was calculated based on the available data of epileptic events within the preceding 3 months. Disease duration was estimated by determining the time from the first reported seizure to the present.

Key Findings:  There were 22 patients (48%) in the epilepsy group and only one patient (5%) in the control group fulfilling the criteria for VLP (p = 0.0005). Subsequently, epilepsy patients were divided into two subgroups according to VLP presence. Patients with VLP had longer disease duration (p = 0.03) compared to those without VLP. Similarly, patients with VLP more frequently had refractory epilepsy (p = 0.03) and had higher monthly seizure frequency (p = 0.02). Analysis of the proportions of generalized seizures (GS) and focal seizures (FS) showed a tendency for higher number of generalized tonic–clonic seizures in the VLP group, but this did not reach statistical significance (p = 0.06). VLP patients tended to be more often on polytherapy (defined as more than one AED per patient) (p = 0.07) as compared to epilepsy patients without VLP. However, if the numbers of AEDs per patients among the subgroups were compared, patients with VLP were treated with more AEDs than patients without VLP (p = 0.01). The study was not sufficiently powered to pinpoint any particular drug or AED combination to influence the appearance of VLP in epileptic patients. In particular, there was no difference in valproate or carbamazepine exposure, considering the percentage of patients exposed or the total daily dose administered.

Significance:  Epilepsy patients more frequently display abnormal SAECGs with VLPs as compared to the control population, and their presence correlates with the disease duration, uncontrolled seizures, and polytherapy. Further longitudinal studies are needed in order to stratify the risk of life-threatening ventricular events in epilepsy patients with VLPs.

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