(P125) IS THE COHABITATION OF SUBCUTANEOUS DEFIBRILLATORS AND LEADLESS PACEMAKERS SAFE?

Background: Subcutaneous implantable cardioverter defibrillators (S-ICDs) and leadless pacemakers (LPs) represent advances in electrophysiology that help prevent lead-related complications associated with transvenous devices. One downside of S-ICDs is their inability to perform anti-bradycardia pacing and anti-tachycardia pacing (ATP), limiting the number of patients eligible for an S-ICD implant. By pairing an S-ICD with an LP, patients in need of both ventricular pacing and sudden cardiac death prevention could benefit from these non-transvenous alternatives. Thus, this study aims to report the safety and non-inferiority in shock efficacy of an S-ICD cohabiting with an LP.

METHODS AND RESULTS: The medical records of 11 patients (5 women) with both an S-ICD and an LP at the Montreal Heart Institute were analyzed from 2013 to 2024. Five (45.5%) patients had the S-ICD before the cohabitation, five (45.5%) originally had an LP, and 1 (9.1%) patient had both devices implanted simultaneously. The mean patient age was 66 ± 6.2 years old, with a mean ejection fraction of 43.6 ± 13.6 %, and 7 (63.7%) patients in secondary prevention. The types of LP included in this study were the Micra VR (8), the Micra AV (2), and the AVEIR VR (1). Two patients were also implanted with a HeartMate device. All patients had an AV block, 4 had complex congenital heart diseases. Five (45.5%) patients were pacemaker dependent. Nine (81.8%) patients previously had a transvenous device, and 8 (72.7%) of them had experienced lead-related complications or infections. During a mean follow-up period of 32.9 ± 19.2 months of device cohabitation, no inappropriate nor appropriate shock occurred. During defibrillation testing (DFT), ventricular fibrillation (VF) was induced in 3 patients with a previously implanted LP and all 3 were successfully terminated without any mis sensing. Five patients had oversensing during the follow-up: 2 dependent patients developed charging episodes, without any inappropriate shocks, and displayed oversensing on their current S-ECGs in clinic, and 3 patients had oversensing episodes detected as atrial fibrillation (AF).

Conclusion: In conclusion, the cohabitation of an S-ICD and an LP does not increase the risk of inappropriate shocks, although pacing-dependent patients should be closely monitored for oversensing. Furthermore, the presence of the LP does not diminish the efficacy of the delivered shocks. This study could allow for more patients in need of pacing to benefit from leadless devices. The upcoming MODULAR ATP trial on communicating ATP-enabled LPs and S-ICDs should fix these interactions.