Should All Individuals With A Non Diagnostic Brugada-Electrocardiogram Undergo Sodium Channel Blocker Test?

BACKGROUND: The diagnostic Br-ECG is characterized by "coved type" ST-segment elevation (type 1) in V1-V2/V3. The sodium channel blocker test is clinically used to unmask diagnostic Br-ECG in patients with non-diagnostic "saddle-back" Br-ECG (type 2 and 3). OBJECTIVES: To assess the prognostic value of the sodium channel blockers test in individuals with a non diagnostic Brugada-ECG (Br-ECG). METHODS: We studied 153 consecutive patients (128 males; age 41.7\ub114.0 years) with a type 2/3 Br-ECG who underwent a sodium channel blocker test with either flecainide (48%) or ajmaline (52%). Non-diagnostic Br-ECGs were identified during evaluation of cardiac arrest in 5 patients (3%), syncope in 36 (24%), cascade family screening in 48 (31%), and incidental ECG in 64 (42%). A spontaneous type 1 Br-ECG was systematically excluded by serial ECGs (6.1\ub10.4) and recording of right precordial leads both at standard and 3(th) -2(nd) intercostal spaces. RESULTS: Sodium channel blocker test was positive in 76 (50%) patients. During a follow-up of 59\ub133 months, 9 (5.9%) patients experienced events such as syncope (n=4), appropriate interventions of defibrillator (n=4) or sudden death (n=1). A positive sodium channel blocker test was associated with a significantly higher event rate in symptomatic patients (p=0.01), but not in asymptomatic individuals (p=0.18). No events occurred among asymptomatic individuals with an incidental non diagnostic Br-ECG. CONCLUSIONS: In asymptomatic individuals with a non diagnostic Br-ECG, the incidence of events is low regardless of sodium channel blocker test result while in symptomatic patients a positive sodium channel blocker test is associated with an adverse arrhythmic outcome and may contribute to risk stratificatio