Potentially high-risk cardiac arrhythmias with focal to bilateral tonic-clonic seizures and generalized tonic-clonic seizures are associated with the duration of periictal hypoxemia.

To investigate potentially high-risk cardiac arrhythmias (PHAs) following focal to bilateral tonic-clonic seizures (FBTCSs) and generalized tonic-clonic seizures (GTCSs) and to study the association of PHAs with seizure characteristics and the severity of associated ictal respiratory dysfunction.

Electrocardiographic (EKG) and pulse oximetry (SpO2 ) data were recorded concurrently with video-electroencephalographic telemetry in the epilepsy monitoring unit (EMU). One minute of preictal EKG, the ictal EKG, and 2 min of ictal/postictal data were reviewed for each seizure. Nonsustained ventricular tachycardia, bradyarrhythmia, and/or sinus pauses were considered as PHAs. FBTCSs/GTCSs with PHAs were compared to those that had only ictal sinus tachycardia.

Data from 69 patients with 182 FBTCSs/GTCSs with usable SpO2 and EKG recordings were available. There were 10 FBTCSs/GTCSs in 10 patients with a PHA. The presence of PHAs was not associated with seizure duration or SpO2 nadir. FBTCSs/GTCSs with a PHA were significantly associated with the duration of oxygen desaturation < 90% when compared with FBTCSs/GTCSs with only sinus tachycardia (Mann-Whitney, p = 0.042). Desaturation duration of <100 s was not significantly associated with occurrence of PHAs (p = 0.110) when compared with seizures that had only sinus tachycardia. The odds ratio for occurrence of PHA was 7.86 for desaturation durations ≥ 125 s versus desaturations < 125 s (p = 0.005). The odds ratio increased to 13.09 for desaturation durations ≥ 150 s (p < 0.001). Preictal and ictal/postictal arrhythmias occurred with focal seizures that did not progress to FBTCSs. Four patients with focal seizures had ictal/postictal PHAs without preictal PHAs. Two of these patients had evidence for prior cardiac disturbance.

PHAs following a single FBTCS/GTCS in the EMU are significantly associated with the duration of ictal/postictal hypoxemia. It is possible that FBTCS/GTCS-associated hypoxemia may trigger fatal cardiac arrhythmias in a subset of susceptible patients dying of sudden unexpected death in epilepsy.