Abstract 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.

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