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.