Successful Elimination of Significant Arrhythmia Burden with Flecainide in an Adolescent with Long QT Syndrome Type 3

Congenital Long QT syndrome (LQTS) is a cardiac channelopathy, which leads to prolongation of the QT interval. This prolongation can lead to ventricular tachyarrhythmias, syncope, and sudden cardiac death. There are various types of LQTS associated with the mutations, which affect the genes coding the ion channels in the myocardial cells. Because of the differences in the ion channel physiology, clinical presentation of the subtypes can show significant differences. The most common types of LQTS are LQT1, LQT2, and LQT3. In LQT1 and LQT2, mutations are in the genes encoding Potassium channels (KCNQ1 and KCNH2 genes). These two subtypes show sensitivity to adrenergic stimuli. In LQT1, episodes are usually exercise-triggered, and in LQT2, episodes are more likely to be related to sudden arousal and emotional stress. Therefore treatment of LQT1 and LQT2 is mainly based on antiadrenergic therapy. LQT3 on the other hand, is a result of a mutation of SCN5A gene, which encodes the Sodium channels. In this type, patients are sensitive to vagal stimuli and episodes tend to occur at rest. Therefore, treatment choices between different subtypes of LQTS vary. In this case report, we report a patient with congenital LQT3 (Y1795C mutation) presenting with implantable cardioverter defibrillator (ICD) storm. Patient's arrhythmia burden was eliminated following successful treatment with flecainide.