Congenital long QT syndrome presenting with a history of epilepsy: Misdiagnosis or relationship between channelopathies of the heart and brain?

Summary A 60-year-old man with a long history of epilepsy was referred for cardiologic evaluation. An earlier diagnosis of epilepsy was made on the basis of his clinical manifestation of tonic–clonic seizure. Electroencephalography (EEG) demonstrated paroxysmal slow waves in response to intermittent photic stimulation. However, electrocardiography (ECG) revealed bradycardia (heart rate, 48 bpm) and marked QT prolongation (QTc 477 ms). ECG monitoring confirmed remarkable QT prolongation; ventricular ectopy triggering torsades de pointes was recorded during seizure. The patient underwent temporary antitachycardia pacing, and an implantable cardioverter defibrillator (ICD) was finally implanted. Long QT syndrome (LQTS) genetic testing was conducted and a diagnosis of LQT2 was confirmed by the identification of mutation in KCNH2 (HERG). LQTS is associated with abnormal channel function due to mutations in ion channel genes. Epilepsy, a disorder of neural function, is also associated with abnormal channel function. The possibility that some channelopathies can manifest as both LQTS and epilepsy is discussed.