Sodium channel blockade (SCB) with a class Ia or Ic antiarrhythmic agent (eg, ajmaline or procainamide, respectively) is used in the unmasking and diagnosis of Brugada syndrome (BrS). SCB is performed frequently as part of family screening or in symptomatic patients with a suggestive electrocardiogram (ECG), and concurrent medications known to potentiate arrhythmias or contraindicated in BrS are withheld prior to testing.1 Lamotrigine (LTG) is currently not contraindicated in BrS or known to be potentially arrhythmic during testing with SCB agents. We report a case illustrating its arrhythmogenic potential and the implications of its concurrent usage during such testing in clinical practice.