Long QT syndrome (LQTS) is one of several primary electrical disorders or hereditary arrhythmia syndromes along with the short QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia. Since its initial recognition in 1957 by Jervell and Lange-Nielsen (Am Heart J. 1957;54:59-68), LQTS has been intimately associated with risk for sudden cardiac death. The implantable defibrillator was developed by Morowski et al (N Engl J Med. 1980;303:322-4) as a treatment to prevent sudden cardiac death. Consequently, implanted cardioverter-defibrillator therapy deserves serious consideration as an important therapy for LQTS.