Electrocardiogram interpretation and class I blocker challenge in Brugada syndrome

Brugada syndrome is characterized by the presence of an electrocardiographic pattern of ST-segment elevation in leads V1 to V3 and a history of sudden cardiac death in the absence of structural heart disease [Brugada P, Brugada J. Right bundle branch block, persistent ST segment elevation and sudden cardiac death: a distinct clinical and electrocardiographic syndrome. A multicenter report. J Am Coll Cardiol 1992;20(6):1391]. The disease usually affects individuals in their 40s, at the prime of their life, and the appearance of cardiac arrest in these otherwise healthy individuals brings an important burden to families and to health care. Brugada syndrome is in several instances a familial disease, caused by mutations in SCN5A in up to 25% of the individuals [Chen Q, Kirsch GE, Zhang D, Brugada R, Brugada J, Brugada P, et al. Genetic basis and molecular mechanism for idiopathic ventricular fibrillation. Nature 1998;392(6673):293]. The identification of the electrocardiographic pattern in an individual will therefore trigger an important cascade of events in the families. Several family members, including children, will be under the scrutiny of a cardiologist to decide on preventive measures, especially if there is a history of sudden death in the family. The presence of abnormal repolarization patterns, which in otherwise sporadic individuals might be classified under normal variations, have become a diagnostic challenge for clinicians facing a family with the disease [Hong K, Brugada J, Oliva A, Berruezo-Sanchez A, Potenza D, Pollevick GD, et al. Value of electrocardiographic parameters and ajmaline test in the diagnosis of Brugada syndrome caused by SCN5A mutations. Circulation 2004;110(19):3023].