Abstracts

Rationale: Patients with epilepsy are at a higher risk of cardiac dysrhythmias both during the peri-ictal period (tachy- or bradyarrhythmias) and the interictal period (reduced heart rate variability, prolonged QT intervals or atrioventricular block), and the biological mechanisms underlying this vulnerability are poorly understood. Interictal electrocardiograms (ECGs) provide an inexpensive and quick screening modality to discover cardiac conduction abnormalities that may identify individuals at risk for ictal dysrhythmias, including those that may underlie Sudden Unexpected Death in Epilepsy (SUDEP). In this study, we describe the relative infrequency with which ECGs are obtained for patients admitted to our epilepsy monitoring unit (EMU). Methods: After obtaining IRB approval, we performed a retrospective chart review of patients admitted to the EMU at the BIDMC over the past two years. Like many busy EMUs around the country, this is a resident-run clinical service supervised by a board certified attending epileptologist. We excluded patients younger than 18 or over 65 years of age. Using electronic medical records and the admission initial note, we collected demographic data, information about comorbidities and ECG results. Results: Out of 186 patients admitted to the EMU that met eligibility criteria, only 57% (106) received 12-lead electrocardiograms as a part of their admission testing. The two groups ("ECG" or "NO ECG") were matched in age (41.3 versus 39.7, respectively) and sex (~39% male versus 30% male, respectively). There was no significant difference between the groups in the incidence of thyroid abnormalities, hypertension, hyperlipidemia, asthma or anxiety/depression. Cardiac disease was not an exclusion criterion. We did identify a greater incidence of a diagnosis of migraine headaches amongst patients who did not receive an ECG (p<0.05, Fisher's exact test). Conclusions: Many EMU patients have medically-refractory epilepsy, and their admissions often involve withdrawal of anticonvulsants for event characterization or presurgical localization. Since previous studies have shown that seizures can be associated with both tachy- and bradyarrhythmias, the lack of baseline assessments of cardiac rhythms prior to anticonvulsant withdrawal/titration is concerning. We identified no specific practice patterns to explain why certain patients received an ECG and why others did not; the two groups were similar in age, sex and major medical comorbidities. As we continue to gather data to help us predict the likelihood of potentially lethal ictally-associated arrhythmias, common easily identifiable ECG abnormalities must be excluded in EMU patients, particularly in cases where seizures may be provoked by anticonvulsant withdrawal. These data suggest that ordering ECGs should be part of all EMU admission protocols.