Abstracts

Rationale: Cardiac arrhythmias may potentially contribute to cardiovascular-related mortality and sudden unexpected death in epilepsy (SUDEP) in patients with chronic drug resistant epilepsy. However, the incidence and nature in this population remain poorly characterized. Methods: This was a prospective cohort study of patients with chronic (disease duration of ≥5 years) drug-resistant epilepsy, recruited following inpatient video-EEG monitoring at The Royal Melbourne Hospital, The Alfred Hospital, or Monash Medical Centre, Melbourne, Australia. An established history of any heart disease was an exclusion criterion. All participants underwent a standard 12-lead ECG, followed by insertion of an implantable cardiac monitor (ICM). The primary outcome was characterization of cardiac arrhythmias in this population. Cardiac arrythmias were defined as: sustained sinus tachycardia (>30s) consisting of ≥140 beats per minute (bpm); sinus bradycardia ≤40 bpm for ≥3 seconds; sinus arrest with pauses or asystole ≥3 seconds; high-degree atrioventricular (AV) block (second-to-third-degree AV block) ≤40 bpm lasting ≥3 seconds; atrial fibrillation defined as the absence of p waves and the presence of R-R irregularity for ≥15s; and ventricular fibrillation. Patients were also instructed to document seizure occurrence in a seizure diary. Results: Thirty-one patients underwent ICM insertion between May 2016 and December 2018. Median age was 41 (range 21 to 67) years, median duration of epilepsy of 23 (range 5 to 62) years, and 17/31 (54.8%) were male. Of the 31 patients, 24 (77.4%) had focal epilepsy, 6 (19.4%) generalized epilepsy, and 1 (3.2%) with unclassifiable epilepsy. 27/31 (87.1%) patients were on antiepileptic drug (AED) polytherapy, and 4 (12.9%) on AED monotherapy. 28 (90.3%) patients were on sodium channel blockers. Cardiac arrhythmias were detected in 28/31 (90.3%) patients during a median follow-up duration of 1.0 years (range 0.3 to 2.8). 25/31 (80.6%) patients were found to have sustained sinus tachycardia and 10/31 (32.3%) patients had sinus bradycardia. Other arrhythmias included slow sinus rate with occasional junctional escape beats in 1/31 (3.2%) patient, wide complex tachycardia with regular QRS complex in 1/31 (3.2%) patient, and sinus rhythm with intermittent bundle branch block and atrial ectopy in 1/31 (3.2%) patient. Most notably, 3/31 (9.7%) patients had serious cardiac arrhythmias, including sinus arrest with ventricular asystole 2/31 (6.5%) and probable ventricular tachycardia (VT) 1/31 (3.2%), requiring urgent cardiologist intervention. In one patient with right temporal lobe epilepsy, sinus arrest occurred with a focal impaired awareness seizure, which was subsequently treated with a permanent pacemaker insertion. In another patient with right temporal lobe epilepsy sinus arrest was asymptomatic. Probable VT was detected twice in the same patient with genetic epilepsy with febrile seizures plus (GEFS+), and in each case, was associated with a tonic-clonic seizure with with fever. Conclusions: Approximately 1 in 10 patients with chronic, drug-resistant epilepsy have a serious cardiac arrhythmia that will go unrecognised in routine monitoring. Cardiac monitoring with an ICM can lead to detection and appropriate management of these arrhythmias. Further studies are required to determine which patients should be referred for monitoring with an ICM, and the significance that this may have in term of prevention of premature mortality. Funding: S.S. is supported by a Ball Grant from the Royal Melbourne Hospital Neuroscience Foundation. R.P. is supported by a Postgraduate Scholarship from the National Health and Medical Research Council (APP1169358). P.P. is supported by an Early Career Fellowship from the National Health and Medical Research Council (APP1163708), and by the Viertel Clinical Investigator Award from the Sylvia and Charles Viertel Charitable Foundation. P.K. is supported by a Medical Research Future Fund from the National Health and Medical Research Council of Australia (APP1136427). P.S. is supported by an Educational Grant from Abbott Medical. T.O. is supported by a Program Grant from the National Health and Medical Research Council of Australia (APP1091593), and the Royal Melbourne Hospital Neuroscience Foundation. In-kind donations were provided by Abbott Medical for cardiac diagnostic devices.