Enhanced QT shortening and persistent tachycardia after generalized seizures

Abstract

Objective: Generalized tonic-clonic seizures (GTCS) are a major risk factor for sudden unexpected death in epilepsy (SUDEP). We investigated whether ictal/postictal cardiac features were dependent on seizure type within individual patients.

Methods: ECG data from patients with medically refractory temporal lobe epilepsy (TLE) undergoing presurgical investigation who had both complex partial seizures and secondarily GTCS during video-EEG telemetry were retrospectively reviewed. Peri-ictal heart rate (HR), corrected QT interval (QTc), HR variability, and cardiac rhythm were assessed.

Results: Twenty-five patients were included in this study. Secondarily GTCS led to higher ictal HR, persistent postictal tachycardia, and decreased postictal HR variability. Moreover, abnormal shortening of QTc occurred in 17 patients mainly during the early postictal phase and significantly more often in secondarily GTCS. Abnormal QTc prolongation occurred in 3 patients with no significant association with GTCS. Benign cardiac arrhythmias occurred in 14 patients and were independent of seizure type.

Conclusions: Our data suggest a substantial disturbance of autonomic function following secondarily generalized tonic-clonic seizures (GTCS) in patients with medically refractory temporal lobe epilepsy. The observed alterations could potentially facilitate sudden cardiac death and might contribute to the association of sudden unexpected death in epilepsy with GTCS.

Figure 1 Secondarily generalized tonic-clonic seizures (SGTCS) last longer, have higher ictal heart rate (HR), and display sustained tachycardia and decreased HR variability (HRV) postictally (A) HR at different time points (white bars: complex partial seizures [CPS]; green bars: SGTCS; pi: postictal). Number of pairs from left to right: 25, 22, 25, 25, 22, 22, 21, 19, 19. p Values from left to right: 1.0, 0.006, 0.002, 0.002, 0.002, 0.002, 0.001, 0.001, 0.001. (B) HRV was similar before seizures (p = 1, 19 pairs), whereas postictal HRV was lower in SGTCS (p = 0.007, n = 19 pairs). (C) Duration of seizures (green bar: SGTCS; p = 0.046, 24 pairs). For all panels: asterisks indicate significance.

Figure 2 Shortening of QT interval (QTc) is more frequent in secondarily generalized tonic-clonic seizures (SGTCS) and predominantly occurs in the early postictal phase (A) QT values corrected with Fridericia formula at different time points. Number of pairs from left to right: 25, 10, 17, 18, 18. p Values: 0.97, 1.0, 0.0011, 0.001, 0.23. (B) Number of seizures with normal QTc (white) and short QTc (green) in complex partial seizures and SGTCS. Twenty pairs with respective available QTc data were included. (C) Number of observations with short QTc at the time of occurrence (pi: postictal). For all panels: asterisks indicate significance.