Impact of Different Pacing Sites on Pre-Implantation Screening Test of Subcutaneous Implantable Cardioverter Defibrillators.

BACKGROUND

Pre-implantation screening is a crucial step in preventing inappropriate sensing in patients with subcutaneous implantable cardioverter defibrillators (S-ICDs). Paced QRS-T morphology may influence screening outcomes. We aimed to explore the impact of pacing rhythm and different pacing sites on pre-implantation screening of S-ICD.

METHODS AND

RESULTS

This prospective, single-center study enrolled patients referred for radiofrequency ablation, with both left and right-heart access. A contact-force ablation catheter was used to mimic ventricular pacing at different sites. Automatic screening tests for S-ICD eligibility were performed during pacing and sinus rhythm. The impact of pacing sites on S-ICD eligibility was assessed. Thirty patients (age 54.0 ± 15.0 years, 73.3% male) were enrolled. The overall passing rate during intrinsic sinus rhythm was 86.7%. Compared with sinus rhythm, conduction system pacing from His bundle or left bundle branch demonstrated comparable pass rates and the number of passed vectors, whereas right ventricular septum (RVS) pacing exhibited significantly lower pass rates and less pass vectors. Among all RVS pacing sites, the lowest pass rate was observed at the apical portion, followed by middle and basal portion (p < 0.001 for all comparisons).

CONCLUSION

Conduction system pacing preserves patient eligibility for S-ICD comparable to sinus rhythm, while RVS pacing significantly impairs sensing performance, with the greatest deterioration observed in apical pacing. These findings underscore the advantages of conduction system pacing in optimizing sensing function for patients eligible for both S-ICDs and pacemakers.