There exist a lot of concern about a possible relation between the syndrome under discussion and other syndromes, particularly right ventricular dysplasia. The recent discovery of the genetic abnormalities of Brugada syndrome in the gene SCN5A located in chromosome 3 should be sufficient to finish this discussion, because the loci so far described in right ventricular dysplasia are located in other chromosomes.

In spite of these considerations, of course it is perfectly possible that some patients manifest two different diseases at the same time, and also there exists electrocardiograms that look similar to Brugada syndrome, but are not caused by the disease (pseudo-Brugada syndrome). Ikeguchi and co-workers (personal communication) have studied a patient with Wolff-Parkinson-White syndrome who was successfully treated by means of radiofrequency catheter ablation. The patient died suddenly two years after ablation. Analysis of the electrocardiograms of this case shows that he also suffered from Brugada syndrome. Thus, he had two syndromes at the same time. It is not unthinkable, therefore, that some patients may suffer from right ventricular dysplasia and Brugada syndrome simultaneously.

Other diseases may result in electrocardiographic manifestations similar to Brugada syndrome. For instance, it is interesting to observe the pictures published from Buenos Aires in 1982 (picture 14). In patients with Chagas' disease Chiale et al. showed that the intravenous administration of ajmaline was of value to uncover latent conduction disturbances, but also what they called "latent disease". In patients with positive serology severe conduction disturbances occurred in one third after the administration of intravenous ajmaline. In 8% of patients they observed the appearance of ventricular arrhythmias and in 7% elevation of the ST segment in the right precordial leads (picture 14). The question arises of the relation between Chagas' disease and Brugada syndrome in these patients. Chiale and co-workers actually considered the ajmaline challenge as a non-specific test capable of detecting myocardial damage. On the light of the recent discovery of the genetic defect underlying Brugada syndrome, the question also arises about the possible occurrence of damage to the sodium channel by Chagas' disease. Although there exist major differences between Chagas' disease and Brugada syndrome, the final common pathway leading to sudden death may be the same: damage to the sodium channel (infectious and inmunologic in Chagas' disease, genetic in Brugada syndrome) with conduction and repolarisation disturbances leading to electrical chaos and ventricular fibrillation.

Other conditions may result in electrocardiograms simulating Brugada syndrome: Steinert's disease (picture 15), pectus excavatum, and mediastinal tumors (Farre J). These should be excluded before diagnosing Brugada syndrome.