Sodium channel blockade unmasked Brugada electrocardiographic pattern in a patient with complete right bundle branch block and early repolarization in the lateral leads.

Early repolarization syndrome (ERS) and Brugada syndrome (BrS) share many electrocardiographic and clinical features, and recently have been collectively grouped as J wave syndrome. However, the effects of sodium channel blockers on the J waves differ greatly between ERS and BrS.