Summary

The differential diagnosis of syncope versus seizures represents a daily challenge for cardiologists and neurologists. Long Q-T syndrome and hypertrophic cardiomyopathy (HCM) are two hereditary arrhythmogenic heart conditions causing syncope in early adulthood. We report the cases of two patients who were reassessed for transient loss of consciousness (TLOC) with convulsions despite treatment. The first patient, a 40-year-old woman, had been diagnosed with epilepsy and was given phenytoin. Her episodes took place while swimming or when in emotional distress and were not followed by post-ictal confusion. An electrocardiogram showed a very prolonged Q-Tc interval. The second patient, a 30-year-old man with HCM in whom a defibrillator had been implanted on the assumption that he was having cardiogenic syncopes, was actually found to have epilepsy. Adequate treatment rendered both patients asymptomatic. In conclusion, the clinical history and 12-lead electrocardiography remain crucial in the management of TLOC, ideally involving both cardiologists and neurologists.