P884A review of the ECGs of patients on antiepileptic medications in an epilepsy monitoring unit

Abstract

Introduction: Epilepsy monitoring units (EMUs) are becoming increasingly used to supervise treatment of patients with epilepsy who are on regular anti-epileptic drugs (AEDs). A number of AEDs are known to have both bradycardic and tachycardic side effects (SEs). However, little is known about the prevalence of abnormal baseline ECG findings in the population of patients routinely treated with these medications. We therefore aim to analyse the ECGs on all new EMU admissions over a period of time and review their AEDs. Method(s): We prospectively reviewed all new admissions to an EMU from January to March 2017. Ethical clearance was obtained from the local ethics committee. Baseline 12-lead electrocardiograms (ECGs) were done on all patients after informed consent. AEDs taken by all patients prior to admission were recorded and their cardiac SEs were catalogued. Heart rate, rhythm, PR interval, QRS duration, QTc interval and T waves were all reviewed. Data were analysed on statistical analysis software and expressed as percentages and means. Result(s): Forty-six patients (21 male, 25 female) on a total of 91 AEDs (mean 2 per patient, mean 6 cardiac SEs per AED) with confirmed epilepsy were admitted to the EMU over a 77-day period. Mean age was 35 years (17-64). One patient (2%) had a prior history of cardiac arrhythmia and had a permanent pacemaker, but otherwise, no patient had any significant cardiac history. For baseline ECGs, 17 (37%) were normal sinus rhythm (NSR) and 29 (63%) were classified as abnormal. Of the abnormal ECGs, 2 (4%) had sinus tachycardia (ST, heart rate (HR) >100bpm), 8 (17%) had sinus bradycardia (SB, HR <50bpm), 3 (7%) had first degree AV block (1oAVB, PR interval >200ms), 3 (7%) had right bundle branch block (RBBB, QRS >120ms with RSR pattern in V1), 11 (24%) had abnormal T-wave inversion (TWI), 1 (2%) had a delta wave with short PR interval, and 1 (2%) was atrial paced (AP). Of the 13 different types of AED used, 77% (10/13) were associated with arrhythmic SEs. Of note, 92% (11/12) of those with conduction system abnormalities (SB, 1oAVB or AP), 73% (8/11) of those with abnormal TWI and 100% (3/3) of those with RBBB were on AEDs with arrhythmic SEs. Conclusion(s): In a comparatively young population of patients diagnosed with epilepsy on regular AEDs and without prior cardiac history, there was a higher than expected prevalence of abnormal baseline ECG findings. Relevantly, the majority of patients with abnormal ECGs were on AEDs with known arrhythmic SEs (particularly the groups with bradycardia, RBBB or abnormal TWI). Further studies may elucidate whether an abnormal ECG at baseline puts patients with epilepsy on regular AEDs at an increased risk for future arrhythmic events.