Proposed mechanisms by which sudden unexplained death syndrome in epilepsy (SUDEP) occurs include cardiac dysrhythmias. We hypothesized that individuals dying of SUDEP would have enlarged hearts compared with normal, increasing the risk of sudden cardiac death should the autonomic nervous system initiate a dysrhythmia. We performed a retrospective case-control study in a medical examiner population, comparing the mean heart mass in a group of individuals who died of SUDEP to a group of individuals with epilepsy who died suddenly due to some unrelated cause (non-SUDEP). We found no significant difference in the mean heart mass between the 2 groups when analyzing the unadjusted data. Upon stratifying the cases by age, however, we found a significant reduction in the frequency of SUDEP in individuals 40 or more years of age with an increased heart mass compared with those younger. This reduced frequency disappeared when cases where the cause of death was indeterminate between SUDEP and heart disease were reclassified from non-SUDEP to SUDEP. With increasing age, the likelihood of finding a cause of death that competes with the possibility of SUDEP increases, making SUDEP appear to be a phenomenon of the young. The inclusion of seizure deaths evaluated in a medical examiner office in studies of SUDEP would provide the benefit of a more certain diagnosis in each given case. Moreover, the inclusion of cases from the medical examiner population would stem attrition in a clinical study due to loss to follow-up.
Epilepsy has the potential to cause sudden death, a condition sometimes identified as sudden unexplained death syndrome in epilepsy (SUDEP). SUDEP is identified by Earnest et al1 as death due to epilepsy with no anatomic cause found at autopsy. Various mechanisms by which SUDEP may occur have been proposed, including asphyxiation,1 cardiac arrhythmia precipitated by a seizure discharge acting via the autonomic nervous system, respiratory arrest,2 and autonomically induced metabolic derangements.3 Individuals with large hearts are at risk for developing a dysrhythmia, independent of the cause of enlargement.4 We hypothesized, therefore, that individuals dying of SUDEP might have large hearts, making them more susceptible to sudden cardiac death should the autonomic nervous system initiate a dysrhythmia. This study compares the mean heart mass of individuals who died of SUDEP to the mean heart mass of individuals with epilepsy who died suddenly due to some cause other than SUDEP.