[Brugada's syndrome]

Abstract

Brugada syndrome is an inherited arrhythmogenic disease, that may cause syncope and sudden cardiac death in young individuals with a normal heart. It is characterized by a typical electrocardiographic pattern: complete or incomplete right bundle branch block and ST segment elevation in leads V1-V3. Thus far, the only gene linked to this syndrome is the gene SCN5A, the gene encoding for the cardiac sodium channel, that is also responsible of the LQT3 form of the Long QT syndrome. Mutations in SCN5A, responsible for Brugada syndrome, cause a functional reduction in the availability of cardiac sodium current. However, only 20-25% of patients affected by this syndrome have mutations on this gene. Therefore, the diagnosis of the syndrome is difficult, because it could manifest at first time as cardiac arrest without any previous symptom and the electrocardiographic pattern could be intermittent, thus a pharmacological challenge with antiarrhythmic class I drugs is required to unmask ST elevation. The clinical management is still empiricial because pharmacological therapies lack to show effectiveness and the only life-saving option is an implantable cardioverter defibrillator (ICD). So the identification of clinical parameters as predictors of adverse outcome for risk stratification has became of outmost importance for the clinical management of these patients, to discover which patients really need an ICD. This review presents clinical and genetic features of Brugada syndrome and the most recent diagnostic criteria. It will be discussed, therefore, the prognostic value of clinical tests, and especially of the programmed electrical stimulation, as prognostic predictors of sudden cardiac death to identify higher risk patients.