Reproducibility and diagnostic usefulness of repeated sodium channel blocker test at higher precordial electrocardiogram recording in a patient with Brugada syndrome

Brugada syndrome was reported for the first time in 19921 and is associated with a characteristic ST-segment elevation in the right precordial leads (V1–V3) in the absence of demonstrable structural heart disease as well as sudden cardiac death owing to ventricular fibrillation (Vf). Brugada syndrome is diagnosed when a coved-type ST-segment elevation is observed in ≥1 right precordial lead in the presence or absence of a sodium channel blocking agent. The diagnostic criteria have been changing and the characteristics of the disease have been assessed continuously.2, 3 It is well known that spontaneous circadian and daily variation of ST-segment morphology is observed in patients with Brugada syndrome, and the sodium channel blocker test can unmask the concealed electrocardiogram (ECG) manifestations of Brugada syndrome, which plays an important role in making the diagnosis.2, 3 However, the reproducibility of the sodium channel blocker test at the usual fourth intercostal space has not been evaluated systematically, much less at higher intercostal spaces, and there have been few reports describing the role of the repeated sodium channel blocker test for the diagnosis. In this report, we present an interesting case of a patient who exhibited different responses to the repeated sodium channel blocker test, which played an important role in the diagnosis.