More evidence-based data are required for a consensus on the aetiology of the so-called Brugada Syndrome

Dear Editor

In the Consensus Report,¹‘Proposed Diagnostic Criteria for the Brugada Syndrome’ the authors assume that this is mainly a functional syndrome related to abnormal repolarization. Although it is popular to classify this syndrome as a channelopathy, it should be noted that SCN5A genetic abnormalities are present in only 10–30% of these patients, and in other populations without the syndrome, as recently reported by Splawski. The presence of the SCN5A mutations, neither explains nor exclude, the presence of structural cardiac abnormality. In addition, the Sudden Unexplained Death Syndrome (SUDS) and Brugada syndrome share the same ECG pattern; however, the SCN5A mutation could not be found in families with this inherited condition described by Sangwatanaroj. The only careful systematic autopsy study of 18individuals who died of SUDS, performed by Kirshner in 1986 showed pathological changes, primarily in the conduction system in virtually all of the hearts. There is other evidence of structural heart disease reported in patients with a typical ‘Brugada ECG’. There have been several studies, including our own, that have clearly shown that this ECG pattern (related to a depolarization abnormality), is present in some patients with concealed forms of right ventricular cardiomyopathy/dysplasia.²Recently, Corrado et al. found that 5% of patients who died suddenly and had autopsied proven ARVC/D had ST segment elevation in the right precordial leads.³Also, Takagi et al. showed wall motion abnormalities by electron beam tomography in the right ventricular outflow tract (n=17) and inferior wall (n=7) in 21 of 26 patients with the Brugada syndrome.⁴Although functional explanations for these abnormalities have been suggested, it will require autopsy data to determine the true cause of these abnormalities.

The elegant experiments of Antzelevitch with in vitro perfused wedged preparationsof canine hearts must be confirmed by clinical evidence, particularly anatomic studies, so that we can better understand whether these ECG abnormalities have an organic or functional basis or can be due to a combination of both.⁵