Cardiac Autonomic Modulation in Seizure Disorders With and Without Interictal Epileptiform Discharges: A...

Background Cardiac autonomic dysfunction is increasingly recognized in epilepsy and has been implicated in cardiovascular complications and sudden unexpected death in epilepsy (SUDEP). Heart rate variability (HRV) provides a non-invasive measure of cardiac autonomic modulation; however, the influence of interictal epileptiform discharges (IEDs) on resting HRV remains uncertain. This study compared HRV among patients with seizure disorders with and without IEDs and a non-seizure neurological comparison group using ECG signals extracted from archived routine electroencephalography (EEG) recordings. Methods This retrospective observational study included 45 adults (15 per group): seizure disorder with IEDs, seizure disorder without IEDs, and non-seizure neurological complaints. A stable, artifact-free five-minute lead II ECG segment was extracted from archived digital EEG recordings after completion of activation procedures. Short-term HRV analysis was performed using LabChart Pro (ADInstruments, Dunedin, New Zealand) and included time-domain, frequency-domain, and nonlinear parameters. Groups were compared using one-way ANOVA or the Kruskal-Wallis test, with appropriate post hoc analyses. Results Demographic characteristics were comparable across the three groups. pNN50 differed significantly among the groups (F(2,42) = 5.127, p = 0.010), with higher values in the non-seizure group than in both seizure groups. Total power (F(2,42) = 3.353, p = 0.045) and high-frequency (HF) power (F(2,42) = 3.905, p = 0.028) also differed significantly, with post hoc differences observed between the non-seizure comparison group and the seizure without IED and seizure with IED groups, respectively. No significant differences were observed in LF power, LF/HF ratio, or nonlinear HRV indices. No HRV parameter differed significantly between the two seizure groups. Conclusions Patients with seizure disorders demonstrated lower vagally mediated HRV than the non-seizure neurological comparison group, whereas the presence of IEDs was not associated with measurable additional alterations in resting cardiac autonomic modulation.