Background: People with epilepsy experience higher rates of cardiac arrhythmia and sudden death than the general population, with the highest risk in genetic epilepsies. Despite growing evidence of a possible cardiac contribution, routine cardiac screening for epilepsy patients is rarely performed. Methods: We performed a single center, retrospective review of patients with developmental epileptic encephalopathies caused by genetic variants expressed in the heart and brain. Clinical history, medications, age, and cardiac evaluation data were extracted. Results: Among 67 patients (56% female), 54 (81%) had at least one ECG. Twenty (37%) had an abnormal ECG. Forty-one had a repeat ECG: 8 showed persistent abnormalities, 7 resolution of abnormalities, and 7 a new abnormality. Five patients with an abnormality did not receive a follow up ECG. Two patients each had histories of cardiac arrest, syncope, and sudden death in a family member. Cardiac phenotypes differed in patients who experienced generalized tonic-clonic seizures and patients with epilepsy for 3+ years. Conclusions: Almost 1/3 of our high-risk epilepsy cohort had history of cardiac events or abnormalities on cardiac testing. Seizure type and epilepsy duration were associated with altered cardiac phenotypes. Since some findings were potentially clinically significant, routine cardiac screening of high-risk epilepsy patients may be warranted.