Assessing the Malignant Ventricular Arrhythmic Substrate in Patients With Brugada Syndrome

Abstract Background Guidelines recommend the use of implanted cardioverter-defibrillators in patients with Brugada syndrome and induced ventricular tachyarrhythmias, but there is no evidence supporting it. Objectives This prospective registry study was designed to explore clinical and electrophysiological predictors of malignant ventricular tachyarrhythmia inducibility in Brugada syndrome. Methods A total of 191 consecutive selected patients with (group 1; n = 88) and without (group 2; n = 103) Brugada syndrome–related symptoms were prospectively enrolled in the registry. Patients underwent electrophysiological study and substrate mapping or ablation before and after ajmaline testing (1 mg/kg/5 min). Results Overall, before ajmaline testing, 53.4% of patients had ventricular tachyarrhythmia inducibility, which was more frequent in group 1 (65.9%) than in group 2 (42.7%; p  2 ; p  2 best identified patients with inducible arrhythmias (area under the curve: 0.98; p  Conclusions In Brugada syndrome dynamic substrate variability represents the pathophysiological basis of lethal ventricular tachyarrhythmias. Substrate size is independently associated with arrhythmia inducibility, and its determination after ajmaline identifies high-risk patients missed by clinical criteria. Substrate ablation is associated with electrocardiogram normalization and not arrhythmia reinducibility. (Epicardial Ablation in Brugada Syndrome [BRUGADA_I]; NCT02641431; Epicardial Ablation in Brugada Syndrome: An Extension Study of 200 BrS Patients; NCT03106701)