Abstracts

Rationale: Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in many epilepsy populations. The most significant risk factors for SUDEP are inadequate seizure control and generalized tonic clonic seizures (GTCS). SUDEP is a heterogeneous event usually occurring following GTCS. Severe and prolonged respiratory dysfunction with hypoxemia and hypercapnia often occur following GTCS. In the small number of SUDEP cases captured in epilepsy monitoring units (EMU), respiratory dysfunction, postictal generalized EEG suppression, and impaired arousal were implicated in SUDEP pathophysiology. In SUDEP captured in EMUs, seizure-induced primary cardiac death was uncommon and some patients may have had pre-existing cardiac disease. There is significantly increased incidence of cardiac channelopathy gene mutations in SUDEP cases relative to controls. Cardiac mechanisms may contribute to some cases of SUDEP. Non-sustained ventricular tachycardia (NSVT), bradyarrhythmias and sinus arrest are associated with respiratory disturbance. GTCS are most frequently associated with sinus tachycardia. However, potentially high-risk arrhythmias (PHA) such as bradycardia, asystole, atrioventricular nodal block, and atrial or ventricular tachyarrhythmias are also reported. We investigated cardiac arrhythmias following secondary generalized tonic clonic seizures in our EMU and possible associations with seizure duration and the severity of associated respiratory dysfunction. Methods: Electrocardiographic (EKG) and pulse oximetry (SpO2) data were recorded concurrently with video and EEG. We retrospectively reviewed data from seventy patients with 186 secondary generalized tonic-clonic seizures who had usable pulse oximetry and EKG data. One minute of preictal EKG and 2 minutes of postictal data were reviewed for each seizure. Seizures with bradyarrhythmia and/or sinus pauses or NSVT were considered as PHA. The Mann-Whitney Rank Sum Test was used to compare seizures with PHA versus seizures with only tachyarrhythmias. Results: EKG arrhythmia findings in the preictal period and in the ictal/postictal period are shown in Table 1. Statistical analysis of seizures with only ictal/postictal sinus tachyarrhythmia and those with PHA are shown in Table 2. The occurrence of PHA are significantly associated with the duration of peri-ictal oxygen desaturation. The odds-ratio of a PHA is 6.09 for desaturation durations ≥100 sec versus desaturations < 100 sec (p=0.028). The odds-ratio increases to 11.75 (p=0.002) for desaturation durations ≥125 sec and further increases to 20.56 (p < 0.001) for desaturation durations ≥ 150 sec. Conclusions: Potentially high-risk cardiac arrhythmias occur after GTCS and are significantly associated with the duration of peri-ictal oxygen desaturation. These findings may be relevant in the pathophysiology of SUDEP in a subset of patients. Funding: None