Progressive HRV (Heart Rate Variability) and QTc-intervals changes have been reported in people with SUDEP (Sudden Unexpected Death in Epilepsy). We evaluated interictal cardiac biomarkers recorded during EMU admissions in nine patients with medically refractory epilepsy (MRE); six patients succumbed to probable or definite SUDEP, two to SUDEP+, and one survived near-SUDEP.
SUDEP is a common cause of death in young adults and risk factors include a history of bilateral or generalized uncontrolled seizures. SUDEP is due to post-ictal cardiorespiratory arrest, but underlying mechanisms may vary. Proposed cardiac biomarkers include decreased HRV and prolonged QTc-intervals, reflecting brainstem-mediated and cardiac mechanisms, respectively.
Artifact-free awake and sleep EEG samples were identified in the first and last hours of the EMU evaluations, in part to evaluate the effect of seizures and medications. Ten consecutive QT-intervals and RR-intervals were measured in each sample over a 60-second period. QT-intervals were corrected for heart rate (QTcF), and the root mean squares of successive differences between normal heartbeats (RMSSD) were calculated to provide a measure for HRV.
Mean age at SUDEP was 34.8+/-9.6. Females had more prolonged QTc-intervals (412 vs 376 msec). HRV measured for EMU stay closest to SUDEP was 28+/-3 for both sexes. HRV decreased in 2 females and 1 male over the course of the EMU stay, but increased in two males. Over the course of 2-4 EMU evaluations, HRV decreased by 7 and 6 msec in one male and female, but remained unchanged in a second female.
HRV appears to be lower in our patients when compared to healthy individuals.
Changes in HRV during an EMU study were noted in females, who also had longer QTc-intervals, suggesting increased susceptibility of autonomic and cardiac remodeling in women.
HRV values decreased over time in two patients, supporting progressive autonomic and cardiac changes associated with MRE.