KCND3 and polymorphic ventricular tachycardia: Recent studies have demonstrated that Brugada syndrome-associated Ito gain-of-function mutations in KCND3-encoded Kv4.3 is believed to mediate an alteration of transmural voltage gradient (epicardium > endocardium), and result in a net outward shift in current and heterogeneous loss of the action potential dome, ST segment elevation on electrocardiogram (ECG), and the development of potentially fatal polymorphic ventricular tachycardia or ventricular fibrillation via phase II reentry [15].