Congenital long QT syndrome (LQTS) is an inherited disorder characterized by QT prolongation and polymorphic ventricular tachycardia known as torsade de pointes. The underlying cellular mechanism is prolonged ventricular repolarization caused by mutations in genes encoding cardiac ion channels or membrane adaptors. The disease can be diagnosed at any age and, very rarely, it can be diagnosed prenatally or in the neonatal period. Isolated noncompaction of the ventricular myocardium (INCVM) is defined as the presence of prominent ventricular trabeculations and deep intertrabecular recesses within the endomyocardium. This report describes a newborn baby presenting with polymorphic ventricular tachycardia whose diagnosis was LQTS and INCVM. Ventricular tachycardia did not respond to medical treatment, and a transient epicardial pacemaker was inserted surgically on his 30th day of life for atrioventricular block and bradycardia. The transient epicardial pacemaker was upgraded to an epicardial intracardiac defibrillator on his 40th day. The concomitant occurrence of INCVM, LQTS, and atrioventricular block needs to be evaluated further.