Sodium channel blocker tests allow a clear distinction of electrophysiological characteristics and prognosis in patients with a type 2 or 3 Brugada electrocardiogram pattern

BackgroundPatients with a type 2 or 3 Brugada syndrome (BS) pattern and a negative sodium channel blocker challenge (SCBC) are not considered as affected. Their arrhythmic prognosis is generally considered good, but it has never been specifically evaluated.ObjectiveThe purpose of this study was to evaluate the arrhythmic prognosis in patients with a type 2 or 3 electrocardiogram (ECG) not converted to type 1 ECG during an SCBC.MethodsClinical data, 12-lead ECG, results of the SCBC and electrophysiological study (EPS), and follow-up were collected.ResultsAmong the 500 patients who underwent an SCBC in our institution, 158 displayed a type 2 or 3 ECG. After the SCBC, 93 (59%) had a type 1 ECG (positive group [PG]), whereas 65 (41%) remained negative (negative group [NG]). An EPS was performed in 31 (33%) PG patients and 15 (23%) NG patients. Ventricular fibrillation was induced in 21 PG patients (67%), whereas no patient in the NG was inducible (P <.001). During a follow-up of 37 ± 17 months, no sudden death occurred. Three syncopes were observed in the NG versus one syncope, two ventricular tachycardias, and one appropriate shock in the PG.ConclusionThis study demonstrates that the presence or absence of coved type ST-segment elevation during the SCBC denotes a profound electrophysiological difference as demonstrated by the absence of inducibility during EPS in the NG that may be responsible for the good prognosis of patients with a type 2 or 3 ECG pattern not converted to type 1.