Brugada syndrome / J wave syndrome [27 genes]

These two entities are produced by the abnormal functioning of some of the cardiac ion channels. They are included in this section because the pathophysiological mechanism is very similar; some authors even postulate that they are part of the same spectrum of diseases.

Brugada syndrome is an inherited arrhythmogenic disorder characterized by elevation of the ST segment in the right precordial leads that predisposes to syncope, malignant ventricular arrhythmias, and sudden death. It is estimated that it may be involved in 18-28% of sudden unexplained deaths.

J wave syndrome is characterized by elevation of the J point ≥1 mm in ≥2 adjacent inferior and/or lateral leads of the electrocardiogram (early repolarization pattern). However, it has been reported that this pattern is overrepresented in patients who have survived cardiorespiratory arrest. The approximate prevalence is 6% in the healthy population, being more frequent in young men and athletes. The genetic etiology has not yet been established, and the level of evidence of causal association with some genes is currently low, so the performance of the genetic study is unknown.

• 1/2,000 individuals

The result of the genetic study on Brugada syndrome has diagnostic and prognostic implications, although with a lower level of evidence than long QT syndrome. Relatives of an index case with a confirmed diagnosis may present asymptomatic, with a normal electrocardiogram and still be exposed to a malignant arrhythmic event in certain situations. In these cases, the genetic study allows us to detect at-risk carriers who must have adequate clinical follow-up, lifestyle recommendations and treatment. On the other hand, patients with pathogenic variants in SCN5A more frequently present conduction disorders and a worse prognosis.

• Presence of an ECG with a spontaneous type I Brugada pattern or a drug-induced type I.
• Patients with suspicion of the disease who present some of the following characteristics: personal or family history of sudden death, previous history of syncope of undetermined origin, and/or presence of ventricular fibrillation of origin indeterminate.
• Survivors of cardiorespiratory arrest of unexplained cause with J-Point Elevation pattern.

• 15-30%