Inappropriate Shocks in Brugada Syndrome Patients With a Subcutaneous Implantable Cardioverter Defibrillator

BACKGROUND: This study aimed to compare inappropriate shock (IAS) rates between subcutaneous implantable cardioverter-defibrillator (S-ICD) and transvenous ICD (TV-ICD) in Brugada syndrome (BrS) patients and identify risk factors for IAS in S-ICD use. METHODS: We enrolled consecutive patients with BrS who underwent ICD implantation between 2013 and 2023. Data on clinical characteristics, S-ICD screening test data, and IAS occurrence were retrospectively analyzed. RESULTS: In total, 74 patients (40 with S-ICDs and 34 with TV-ICD) were enrolled in the study. During a median follow-up of 4.6 years, IAS occurred in nine S-ICD and three TV-ICD patients, exhibiting a non-statistically significant trend (log-rank p = 0.103) toward a higher incidence in the S-ICD group. The incidence of IAS related to non-atrial tachyarrhythmia (non-AT) causes was significantly higher in the S-ICD group than in the TV-ICD group (log-rank p = 0.014). Fewer electrocardiography (ECG) sensing vectors passing the screening test at both the baseline and exercise test (hazard ratio [HR] 0.31, 95% confidence interval [CI] 0.09-0.85; p = 0.21) and detection of ATs (HR 5.25, 95% CI 1.15-24.05; p = -0.048) were associated with IAS in patients with S-ICD. CONCLUSION: No significant difference was observed in the overall incidence of IAS between the S-ICD and TV-ICD groups; however, IAS due to non-AT causes occurred more frequently in the S-ICD group. Fewer ECG sensing vectors passing screening were significantly correlated with the IAS when exercise test results were considered. Therefore, ECG screening, including exercise testing, is preferable for S-ICD candidates.