Electrophysiological Study Prognostic Value and Long-Term Outcome in Drug-Induced Type 1 Brugada Syndrome: The IBRYD Study

Objectives: This study aimed to retrospectively assess long-term outcome and the prognostic role of electrophysiological study (EPS) for risk stratification of drug-induced type 1 Brugada syndrome (BrS) patients.

Background: BrS is a hereditary cardiac disease, predisposing to sudden cardiac death. Few real-world data are available on long-term outcomes of drug-induced type 1 BrS patients, and questions about risk stratification still remain unanswered.

Methods: The IBRYD (Italian Brugada Syndrome) study is a multicenter observational retrospective study. A total of 226 drug-induced type 1 BrS patients were enrolled from 9 Italian tertiary referral institutions. Primary endpoint was a composite of appropriate implantable cardioverter-defibrillator (ICD) therapy and sudden cardiac death. The authors further assessed clinical predictors to ICD implantation, as well as for arrhythmia induction at EPS, along with EPS as potential risk factor for the outcomes of interest.

Results: 142 patients (62.8%) received an ICD due to syncope and/or inducible ventricular tachyarrhythmias at EPS. During a median follow-up of 106 months, 11 patients (4.9%) experienced primary outcome events. The ICD therapy median annual incidence over 8 years was 0.38% (interquartile range: 0% to 1.47%). Ventricular tachyarrhythmia inducibility during EPS was not predictive of arrhythmic events in ICD recipients versus non-ICD patients and in symptomatic versus asymptomatic subgroups, showing a low positive predictive value (9.6% and 8.9%, respectively) versus a high negative predictive value (96.6% and 95%, respectively). The authors reported 29 ICD-related complications and 4.9% inappropriate shocks.

Conclusions: Drug-induced type 1 BrS patients have a very low arrhythmic risk. Clinical decision for implantation is supported by syncope and/or EPS positivity, though they fail to stratify high-risk patients. A better risk-to-benefit ratio should be pursued, considering both arrhythmic risk and ICD-related complications.