Brugada syndrome--an update.

A diagnostic triad characterizes Brugada syndrome. It consists of a right bundle branch block, ST-segment elevation in leads V1-V3 and sudden cardiac death (SCD). Approximately 50% of patients with Brugada syndrome noted to have familial occurrence, this suggests a genetic component of the disease. Mutations in gene SCN5A, an encoder for human cardiac sodium channel on chromosome 3p21, causes Brugada syndrome. Before considering the diagnosis of Brugada syndrome, exclude precordial ST-segment elevation secondary to acute coronary syndrome, electrolyte imbalance, myocarditis, drug over dosage (cocaine, tricyclic antidepressants), and arrhythmogenic right ventricular cardiomyopathy/dysplasia. Intravenous administration of ajmaline, flecainide, and procainamide may exaggerate the ST-segment elevation, or unmask it when it is initially absent in patients with suspected Brugada syndrome. Programmed electrical stimulation (PES) may help in risk stratification, and in some cases, establish the diagnosis. However, the accuracy of PES in predicting outcome is debatable, especially in patients showing an asymptomatic Brugada ECG, and reporting no family history of SCD. Treatment with an implantable cardioverter-defibrillator (ICD) is the only established effective therapy for the disease. With ICD therapy, the mortality rate at a 10 year follow-up was 0%. Supporting data for long-term pharmacological therapy with quinidine, or isoproterenol for prevention of SCD, in these patients, is uncomplete. Future advances in understanding the molecular mechanisms of Brugada syndrome may provide answers to many of the controversial issues in the management of this disease.