Beta-blocker is the first line drug therapy for congenital long QT syndrome. However, in some children this drug is ineffective. In a non-responder patient, Shimizu et al. used Mexiletine to suppress the ventricular arrhythmias, obtaining a good result. In the high risk patient, the ICD is necessary. However the implantation of a device in small children can have technical problems. We report a case of a child affected by long QT syndrome with recurrent episodes of syncope due to self-limiting torsade de point/ventricular fibrillation, successfully treated by an association of mexiletin and propanolol, and in whom an ICD was implanted with a new subcutaneous approach.