Impact of Atrial and Dual‐Chamber Leadless Pacing on Subcutaneous Implantable Cardioverter‐Defibrillator Screening Eligibility

INTRODUCTION: Leadless pacemakers (LPs) are increasingly used in patients at high risk of transvenous lead complications. If indications for implantable cardioverter-defibrillator (ICD) therapy arise later, a subcutaneous ICD (S-ICD) may represent an attractive option. However, S-ICD implantation requires pre-implant electrocardiographic screening, and pacing may impact implantation eligibility. Thus, the purpose of the present analysis was to evaluate S-ICD screening eligibility in patients with right atrial (RA) and dual-chamber (DR) LP during intrinsic rhythm, atrial pacing, and dual-chamber pacing. METHODS AND RESULTS: Patients implanted with active-fixation RA and dual-chamber LP systems underwent S-ICD screening using the automated screening tool. Electrocardiographic parameters were assessed during intrinsic rhythm, atrial pacing (AAI), and dual-chamber pacing (DDD). Screening eligibility was assessed separately for each rhythm. Combined eligibility was defined as the presence of at least one acceptable vector in intrinsic and paced rhythms. Forty-one patients were included (median age 67 years; 61% female). During intrinsic rhythm, at least one acceptable vector was present in 91.4% of patients. Screening eligibility remained high during atrial pacing (77.1%) but decreased substantially during dual-chamber pacing (33.3%). Primary and secondary sensing vectors demonstrated the highest screening success across rhythm conditions, with positive rates of 60.0% and 62.3% for AAI, and 18.5% and 11.1% for DDD pacing. CONCLUSION: In patients with RA and DR LPs, S-ICD screening eligibility is preserved in most cases during intrinsic rhythm and atrial pacing, but markedly reduced during DDD pacing. Pacing mode should be considered when evaluating the feasibility of combining LP systems with an S-ICD.