Recurrence risk of ictal asystole in epilepsy

Abstract

Objective: To determine the recurrence risk of ictal asystole (IA) and its determining factors in people with epilepsy.

Methods: We performed a systematic review of published cases with IA in 3 databases and additionally searched our local database for patients with multiple seizures simultaneously recorded with ECG and EEG and at least one IA. IA recurrence risk was estimated by including all seizures without knowledge of the chronological order. Various clinical features were assessed by an individual patient data meta-analysis. A random mixed effect logistic regression model was applied to estimate the average recurrence risk of IA. Plausibility of the calculated IA recurrence risk was checked by analyzing the local dataset with available information in chronological order.

Results: Eighty patients with 182 IA in 537 seizures were included. Recurrence risk of IA amounted to 40% (95% confidence interval [CI] 32%-50%). None of the clinical factors (age, sex, type and duration of epilepsy, hemispheric lateralization, duration of IA per patient) appeared to have a significant effect on the short-term recurrence risk of IA. When considering the local dataset only, IA recurrence risk was estimated to 30% (95% CI 14%-53%). Information whether IA coincided with symptoms (i.e., syncope) or not was given in 60 patients: 100 out of 142 IAs were symptomatic.

Conclusion: Our data suggest that in case of clinically suspected IA, the recording of 1 or 2 seizures is not sufficient to rule out IA. Furthermore, the high short-term recurrence risk favors aggressive treatment, including pacemaker implantation if seizure freedom cannot be achieved.

Figure 1. Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow chart of search strategy and study selection

*With at least 1 ictal asystole and more than 1 seizure simultaneously recorded with EEG and ECG.

Figure 2. Distribution of recurrence risk of ictal asystole (IA) and of number of IAs

(A) Individual recurrence risk of IA is plotted vs the total number of recorded seizures per patient. A jitter was used to avoid overplotting. The black line indicates the estimated average recurrence risk of IA with the 95% confidence interval (blue rectangle). (B) Individual number of IAs is plotted vs the total number of recorded seizures per patient.

Figure 3. Histograms of the individual recurrence risk of ictal asystole (IA) and of mean IA duration per patient

(A) The individual IA recurrence risk (as calculated by the model in %, bin size 10%) is plotted vs the absolute frequencies. (B) The mean IA duration per patient (in seconds; bin size 3 seconds) is plotted vs the absolute frequencies. One observation with an IA of 96 seconds is not included in the graph.