Abstract 19230: Is Sodium Channel-Blocker Test Justified in All Subjects With a Non-Diagnostic Brugada-Like ECG?
Background: Non diagnostic Brugada-like ECG abnormalities, which overlap with normal early repolarization, include J point elevation ≥2 mm with a saddle-back ST-segment elevation, either ≥1mm (type 2) or <1mm (type 3). Conversion of type 2 or 3 to type 1 (i.e. coved-type ST-segment elevation ≥2mm) after sodium channel blocker (SCB) administration is considered diagnostic for Brugada syndrome and is currently tested in the clinical practice for differential diagnosis. This study was designed to assess whether systematic SCB test impacts risk stratification and outcome of individuals with a non diagnostic Brugada-like ECG.
Methods: We studied 152 patients (127 males; age 42±14 years) with type 2 or 3 Brugada ECG who underwent a SCB test, either by flecainide (74 pts; 39%) or by ajmaline (78 pts; 61%). The abnormal ECG was identified during the investigation of syncope of unknown origin in 40 patients (26%), aborted sudden death (SD) in 4 (3%), study of family members of patients with Brugada syndrome or SD in 43 (28%), or routine ECG screening in 65 (43%).
Results: The SCB test was positive in 75 of 152 (49%) patients. Afterwards 48 of 75 (64%) patients underwent a programmed ventricular stimulation, 19 (25%) were inducible, and 13 (17%) received an ICD. During a follow-up of 49±30 months, 9 patients experienced arrhythmic events such as syncope (n=4), appropriate ICD discharges (n=4), and SD (n=1). Individuals with a positive SCB test had a significantly higher rate of events [8/75 (10.6%) vs 1/77 (1.33%); log rank=0.015]. Induction of a diagnostic type 1 ST-segment elevation by SCB test was a significant predictor for events in patients with a positive family history and/or symptoms (log rank=0.014), while in subjects with a negative familial/personal history was not (log rank=0.343). There were no significant differences in the predictive value of flecainide- and ajmaline-SCB test.
Conclusions: In the absence of a positive family history or symptoms, systematic SCB test is not justified in individuals with non-diagnostic Brugada-like ECG abnormalities because it does not provide additional value for clinical management and prevention of SD. Instead, SCB test may contribute to arrhythmic risk stratification in patients with a positive clinical history.
- © 2010 by American Heart Association, Inc.