Brugada Syndrome : Diagnosis Clinical Manifestations Risk Stratification
Electrocardiographically characterized by a distinct ST-segment elevation in the right precordial leads Brugada syndrome (BrS) is an arrhythmogenic disease reported to be responsible for at least 4% of all sudden deaths (at least 20% of sudden deaths in those without structural heart disease) and is a leading cause of death in subjects under the age of forty years. Global prevalence of the BrS varies from 5% to 20% in every 10000 inhabitants worldwide and it is considered endemic in Asian and Southeast Asian countries.
The diagnosis is mainly based on electrocardiographic features and may be hampered by incomplete penetrance particularly because of dynamic ECG manifestations.
As far as we know inheritance occurs via an autosomal dominant mode of transmission and about eighteen genes have been associated with BrS; thus far genetic abnormalities are found in 30-50% of genotyped BrS patients. Mutations in the cardiac sodium channel gene SCN5A are identified in 11–28% of patients with BrS with over 300 different mutations of SCN5A having been identified as the list still grows. Because a genotype remains lacking for at least half of BrS probands a negative genetic test does not rule out BrS.
Febrile states dysionia and many drugs such as vagotonic agents sodium channel blockers á-adrenergic agonists â-adrenergic blockers antidepressants and alcohol and cocaine toxicity may unmask the electrocardiographic concealed ECG manifestations of BrS.
Identifying patients with BrS at risk of malignant arrhythmias and sudden cardiac death remains the most important objective and therefore the fundamental question remains on the best strategy for assessing the real disease-associated arrhythmic risk especially in asymptomatic patients.