Predictors of inappropriate shock in Brugada syndrome patients with a subcutaneous implantable cardiac defibrillator

Background: Subcutaneous implantable cardioverter defibrillators (S-ICDs) avoid complications secondary to transvenous leads, but inappropriate shocks (ISs) are frequent. Furthermore, IS data from patients with Brugada syndrome (BrS) with an S-ICD are scarce. Objective: We aimed to establish the frequency and predictors of IS in this population. Methods: We analyzed the clinical and electrocardiographic characteristics, automated screening test data, device programming, and IS occurrence in adult patients with BrS with an S-ICD. Results: Thirty-nine patients were enrolled (69% male, mean age at diagnosis 46 ± 13 years, mean age at implantation 48 ± 13 years). During a mean follow-up of 26 ± 21 months, 18% patients experienced IS. Patients with IS were younger at the time of diagnosis (36 ± 8 vs. 48 ± 13 years, p =.018) and S-ICD implantation (38 ± 9 vs. 50 ± 23 years, p =.019) and presented with spontaneous type 1 Brugada electrocardiogram pattern more frequently at diagnosis or during follow-up (71% vs. 25%, p =.018). During automated screening tests, patients with IS showed lower QRS voltage in the primary vector in the supine position (0.58 ± 0.26 vs. 1.10 ± 0.35 mV, p =.011) and lower defibrillator automated screening score in the primary vector in the supine (123 ± 165 vs. 554 ± 390 mV, p =.005) and standing (162 ± 179 vs. 486 ± 388 mV, p =.038) positions. Age at diagnosis was the only independent predictor of IS (hazard ratio = 0.873, 95% confidence interval: 0.767–0.992, p =.037). Conclusion: IS was a frequent complication in patients with BrS with an S-ICD. Younger age was independently associated with IS. A more thorough screening process might help prevent IS in this population.