Clinical differences between drug-induced type 1 Brugada pattern and syndrome

Background: Diagnosis of Brugada syndrome (BrS) may be established by exposing a Type 1 Brugada pattern using a sodium channel blocker. Data on the outcomes of different patient populations with drug-induced Type 1 Brugada pattern are limited. The present study reports on the characteristics and outcome of subjects with ajmaline induced Type 1 Brugada pattern. Methods: A multicenter retrospective study including all consecutive cases of ajmaline-induced Type 1 Brugada pattern from seven centers. Results: A total of 260 patients (69.9% males, mean age 43.4 +/- 13.5) were included. Additional characteristics included history of syncope (n = 56, 21.5%), family history of BrS (n = 58, 22.3%) or sudden cardiac death (n = 47, 18.1%) and ventricular fibrillation (n = 3, 1.2%). Patients were divided into those meeting current diagnostic criteria for drug-induced BrS (DIBrS) and compared to the drug-induced Brugada pattern (DIBrECG). Females were significantly overrepresented in the DIBrS group (n = 50, 40% vs. n = 29, 21.5%, p = .001). A significantly higher prevalence of type 2/3 Brugada ECG at baseline was found in the DIBrECG group (n = 108, 80.8% vs. n = 75, 60% in the DIBrS, p = .026). During a median follow up of three (IQR 1.50-5.32) years, a single event of significant arrhythmia occurred in the DIBrS group. Conclusion: Less than half of subjects with ajmaline-induced Brugada pattern met current criteria for BrS. These individuals had very low rate of adverse outcomes during a follow up of 3 years, irrespective of the indication for the test or eligibility for the BrS diagnosis.