Efficacy of complex signal identification-guided redo ablation for atrial fibrillation
H Kono, K Hiroshima, H Nagai, H Chinen, N Oyanagi, K Misonou, K Onuki, M Kuroda, J Hirokami, T Katsuki, R Kuji, K Korai, M Fukunaga, M Nagashima, K AndoAbstract
Background
Fractionated electrograms represent areas of conduction heterogeneity that may harbor arrhythmogenic substrate in atrial fibrillation (AF). The CARTO 3 Version 8 system introduces the Complex Signal Identification (CSI) module, enabling automated detection and quantification of electrogram fractionation. Although CSI-guided ablation has shown feasibility in de novo AF ablation, its value during repeat ablation procedures remains uncertain.
Purpose
This study aimed to evaluate the procedural characteristics and clinical outcomes of CSI-guided ablation in patients undergoing repeat ablation for recurrent atrial arrhythmias after prior pulmonary vein isolation (PVI).
Methods
We retrospectively analyzed 100 consecutive patients who underwent redo ablation for recurrent atrial arrhythmias between January 2024 and May 2025 using the CARTO 3 system. Substrate mapping was obtained during sinus rhythm or atrial pacing. When PV reconnection was observed, re-isolation (re-PVI) was completed. Subsequently, arrhythmia induction was performed; non-PV triggers were identified based on the CSI algorithm and targeted for ablation. In cases without clear triggers, substrate modification was guided by regions with a CSI score ≥8.5. Post-procedural follow-up was conducted at 3, 6, and 12 months with 12-lead ECG or Holter monitoring.
Results
The mean age was 69 ± 10 years, and 61 patients (61%) were male. Non-PV triggers were documented in 47 patients (47%), and CSI-guided ablation was applied. Re-PVI was required in 55 patients (19 [40%] in CSI-guided and 36 [68%] in non-CSI cases). A total of 110 non-PV foci were identified, with a mean CSI score of 9.3 ± 1.4. Mean procedure and fluoroscopy times were 177 ± 54 and 25 ± 16 minutes in the CSI group versus 141 ± 55 and 18 ± 11 minutes in the non-CSI group, respectively. Additional ablation lines such as box isolation, roof line, and CTI ablation were performed as needed. During a median follow-up of 200 days, the arrhythmia-free survival rate tended to be higher in the CSI group (hazard ratio 0.47; 95% CI 0.16–1.35; p = 0.16), though statistical significance was not reached.
Conclusion
CSI-guided ablation demonstrated a favorable trend toward improved arrhythmia-free survival in redo AF procedures, suggesting that automated identification of complex electrograms may facilitate the recognition of non-PV substrates. The integration of CSI mapping could support individualized substrate modification strategies, warranting further prospective validation in larger cohorts.Outcome of CSI-guided ablationPatient Characteristics