Brugada Syndrome

It is a rare hereditary arrhythmia that increases the risk of cardiac arrest and does not produce structural alterations in the heart.

Brugada syndrome is an inherited cardiac disorder that produces arrhythmia and increases the predisposition to sudden cardiac death even when the heart has a normal structure. Its diagnosis is based on an electrocardiogram study characterized by an ST-segment elevation of 0.2 mV in the right precordial leads (V1 to V3).

This pathology is transmitted following an autosomal dominant pattern of inheritance. However, in a significant proportion of patients, the disease may be sporadic, that is, absent in other relatives. The first gene to be linked to Brugada syndrome is SCN5A, which codes for the cardiac sodium channel. It is now known that this syndrome is heterogeneous and more genes are implicated in its development such as KCND3, SCN3B and CACNA1C.

The worldwide prevalence estimate is 1 case per 2,000 population, however, it may vary depending on ethnicity and geographic region. In Asian and Middle Eastern countries the prevalence is higher (1/270-625) than in Europe (1/10,000) and North America (1/20,000).

Symptoms

The disease is more common in men than in women (with a sex ratio of 8:1) and usually appears during the third or fourth day of life.

Brugada syndrome usually manifests with tachycardia at rest or during sleep. In some cases, the tachycardia does not resolve spontaneously and can lead to sudden death. Triggers for arrhythmia include fever, large meals, or certain drugs (including antiarrhythmics or antidepressants). Most patients are asymptomatic, 20-30% have syncope and 8-12% suffer at least one cardiac arrest.

Disease management

The use of an implantable cardioverter defibrillator (ICD) is the only proven therapeutic option for primary and secondary prophylaxis of sudden death. The drug quinidine is recommended for the prevention of primary manifestations, although its use in asymptomatic patients is controversial.

A new therapeutic option in higher-risk patients is epicardial ablation of the right ventricular outflow tract.

It is important to avoid the use of medications that may cause or exacerbate arrhythmias.

Genes analyzed

SCN5A

Bibliography

Baruteau AE, Kyndt F, Behr ER, et al. SCN5A mutations in 442 neonates and children: genotype-phenotype correlation and identification of higher-risk subgroups. Eur Heart J. 2018 Aug 14;39(31):2879-2887.

Brugada R, Campuzano O, Sarquella-Brugada G, et al. Brugada Syndrome. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle. 2005 Mar 31 [updated 2022 Aug 25].

Veltmann C, Barajas-Martinez H, Wolpert C, et al. Further Insights in the Most Common SCN5A Mutation Causing Overlapping Phenotype of Long QT Syndrome, Brugada Syndrome, and Conduction Defect. J Am Heart Assoc. 2016 Jul 5;5(7):e003379.