WASHINGTON — Patients with refractory epilepsy may be at increased risk for cardiac arrhythmias and resultant cardiac ischemia during seizures, as well as interictal sinus rhythm pauses, Dr. Maromi Nei reported in a poster at the joint annual meeting of the American Epilepsy Society and the American Clinical Neurophysiology Society.
In some cases, such arrhythmias may be a contributing factor to sudden unexpected death in epilepsy (SUDEP), said Dr. Nei of the Jefferson Comprehensive Epilepsy Center, Philadelphia, although more study is necessary to confirm this association.
SUDEP accounts for 8%–17% of deaths among people with epilepsy and is most common in those with refractory disease. SUDEP is defined as sudden, unexpected, nontraumatic, nondrowning death in an individual with epilepsy, witnessed or unwitnessed, in which postmortem examination does not reveal an anatomic or toxicologic cause for the death.
Using an implantable cardiac monitoring device, Dr. Nei recorded heart rhythm in 14 patients (mean age 40 years) with refractory epilepsy for a mean of 10 months. Epilepsy was idiopathic generalized in two, symptomatic generalized in three, and partial in nine. They had failed a mean of seven antiepileptic drugs, and eight had failed epilepsy surgery. None of the patients had a history of heart disease.
A subcutaneous cardiac loop recording device was implanted in all patients. The cardiac monitor was programmed to record when the heart rate fell below 30 beats per minute (BPM) or when it exceeded 180 BPM. Patients were asked to activate the device at the time of any seizures, episodic loss of consciousness, presyncope, or palpitations. They also kept diaries documenting these events.
At the conclusion of monitoring, patients had experienced a mean of 37 seizures each (range 2–236). Their mean ictal heart rate was 110 BPM (range 76–198).
Two patients had T wave inversions during their seizures. One patient had ST segment elevation during seizures, and one patient had frequent atrial premature contractions in the postictal period. Sinus arrest of up to 4.8 seconds occurred in one patient during sleep that was not associated with seizure. All other patients had sinus rhythm pauses or sinus tachycardia associated with their seizures. The significance of these rhythm disturbances is unknown, Dr. Nei said in an interview.
The premature atrial contractions are probably not clinically significant, but are consistent with an increase in autonomic stimulation occurring with the seizure, she added.
The case of sinus arrest suggests that there could be an increase in vagal tone that might result in an increased risk for sinus arrest, particularly during sleep. “This is important because SUDEP often occurs during sleep, and this finding suggests that one possible mechanism for SUDEP is sinus arrest,” she said.