Two patients, ages 19 and 12 years, and a review of 8 previous cases of prolonged QT syndrome presenting as epilepsy are reported from the Department of Neurology and Hospital for Joint Diseases Epilepsy Center, New York University, New York. The 19 year old woman presented with “blackout spells” at 13 years. Some were a transient light-headedness and weakness, while other attacks progressed to tonic-clonic seizures with loss of consciousness. CT, EEG, ECG, and Holter monitor were normal. Echocardiogram showed mitral valve prolapse. Carbamazepine was ineffective, and within 2 months she was found dead at home. Review of ECGs revealed a prolonged QT interval, previously unrecognized. The 12 year old boy was referred with intractable seizures since 4 years of age. He also had “panic attacks” with tachycardia, dyspnea, palm sweating, and limpness. Numerous AEDs were without benefit. EEG and ECG were normal. A Holter monitor revealed ventricular tachycardia and prolonged QT syndrome. Of a total of 10 patients, 5 had family histories consistent with congenital prolonged QT syndrome (ie. sudden death or deafness). The first convulsion occurred at an average age of 4 years. Time to diagnosis ranged from 1 to 28 years. Presyncope and “lifelessness” prior to seizures were common complaints. The beta blocker, propranolol, the mainstay of therapy, is successful in most patients. Some require a pacemaker or implantable cardiac defibrillator. 
COMMENT. Diagnosis of this life-threatening condition may be difficult, but several factors should alert the neurologist to the cardiac origin of the seizures: 1) history of tachycardia, and presyncopal or lifeless feelings prior to onset of convulsive attacks; 2) normal neurologic exam and EEG: 3) family history of deafness, cardiac arrhythmia, or unexpected sudden death; and 4) lack of response to antiepileptic drugs. Familial, autosomal recessive or dominant, and acquired types of prolonged QT interval are recognized. The mortality may be as high as 70% if unrecognized and untreated.