Cardiac> Sudden, Unexplained Death in Epilepsy

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Cardiac Dysrhythmias May Be an Important Cause of Sudden, Unexplained Death

in Epilepsy

Laurie Barclay, MD

Dec. 17, 2004 — Cardiac dysrhythmias may be important as a cause of sudden,

unexplained death in epilepsy, according to the results of a prospective,

long-term study published in the Dec. 18/25 issue of The Lancet.

" We have shown that implantable loop recorders can identify potentially fatal

cardiac abnormalities in patients with epilepsy, and suggest that the

incidence of bradycardia and asystole has previously been under-reported, "

senior

author S. Duncan, from the National Hospital for Neurology and Neurosurgery

in London, U.K., says in a news release. " Asystole underlies a proportion of

sudden unexpected deaths in epilepsy, which could be prevented by

cardiac-pacemaker insertion. "

At one hospital in the U.K., 20 patients with refractory focal seizures

received an implantable loop recorder programmed to record automatically in the

presence of bradycardia (<40 beats per minutes) or tachycardia (>140 beats per

minute). If a seizure developed, patients and relatives could also begin ECG

recording with an external activator device. Implantable loop recorder data were

analyzed regularly and correlated with seizure diaries.

During more than 220,000 patient-hours monitored over 24 months, ECGs were

captured on implantable loop recorders in 377 seizures. One patient withdrew

from the study. In 16 patients, median heart rate during habitual seizures was

greater than 100 beats per minute. Ictal bradycardia (less than 40 beats per

minute) occurred in only eight recorded events (2.1%) in seven patients. Of four

patients (21%) with bradycardia or periods of asystole who subsequently had

permanent pacemaker insertion, three patients (16%) had potentially fatal

asystole.

" Clinical characteristics of patients with peri-ictal cardiac abnormalities

are closely similar to those at greatest risk of sudden unexpected death in

epilepsy, " the authors write. " Asystole might underlie many of these deaths,

which would have important implications for the investigation of similar

patients

and affect present cardiac-pacing policies. "

Study limitations include small sample size.

The authors report no conflict of interest. Medtronic supported this study

and supplied the Reveal Plus devices. The Research and Development Directorate

of University College London Hospitals NHS Trust provided financial support.

In an accompanying commentary, Lawrence J. Hirsch and W. Hauser, from

Columbia University in New York, N.Y., call for larger confirmatory studies

before considering changes in clinical practice.

" The study provides the first real hope that some cases of sudden unexplained

death in epilepsy (SUDEP) might be preventable, " they write. " Although

non-cardiac causes remain difficult to prevent, permanent pacemaker insertion

might

prevent the consequences of bradyarrhythmias including SUDEP. " " This study

suggests that patients at high risk for SUDEP should be studied with

subcutaneous

electronic loop recorders for long periods, or until a potentially fatal

arrhythmia is recorded, " they conclude. " These cases show it is clearly

inadequate

to simply record electrocardiograms for a few weeks or a few seizures. "

The editorialists report no conflict of interest.

The Lancet. 2004; 364:2212-2219

Reviewed by D. Vogin, MD