True right bundle branch block masking the typical ECG in Brugada syndrome.

A patient with a family history of sudden cardiac death and a structurally normal heart presented with a resting ECG intermittently displaying a saddle-type Brugada-ECG, which could be reproducibly converted to a coved-type ECG pattern suggestive of Brugada syndrome. However, no ST-segment changes occurred in the presence of a true right bundle branch block (RBBB) in the same patient. In consideration of the inalienable diagnostic criterion of dynamic ECG abnormalities in the right precordial leads in Brugada syndrome, setting the diagnosis in patients with true RBBB may be unattainable.