Functional Gaps and Atrial Fibrosis as Predictors of Early Arrhythmia Recurrence After Robotic-Enhanced Hybrid Ablation for Persistent Atrial Fibrillation.

Background: Robotic-enhanced hybrid ablation (RE-HA) is a promising strategy for persistent (PsAF) and long-standing persistent atrial fibrillation (LS-PsAF). The impact of post-epicardial conduction gaps and atrial fibrosis on early arrhythmia recurrence (EAR) is unclear.

Objective: To assess whether conduction gaps and atrial fibrosis predict EAR within 3 months after the epicardial stage of RE-HA.

Methods: Forty-two PsAF/LS-PsAF patients underwent RE-HA with left atrial appendage closure. High-density endocardial mapping at 3 months identified fixed (present in all maps) and functional (present in ≥1 but not all maps) conduction gaps. Atrial fibrosis was quantified by pre-procedural cardiac magnetic resonance (CMR).

Results: Gaps were found in 18 patients (42.3%): functional in 10 (23.8%) and fixed in 13 (31.0%), with 5 (12%) showing both. EAR occurred in 12 patients (28.6%), AFL in 10/12 (83.3%). Gaps predicted AFL (OR 4.56; p = 0.003) and EAR (OR 3.50; p = 0.005). Left atrium LGE ≥ 10% independently predicted EAR (OR 7.50; p = 0.019) with no interaction with gap presence (p = 0.24). Total RF time was similar between groups despite more gaps in recurrence cases, reflecting procedural factors beyond gap count. Roof-line gaps predominated and colocalized with epicardial fat on CMR.

Conclusion: Delayed high-density mapping after RE-HA reveals fixed and functional conduction gaps, especially at the roof line, that-together with pre-ablation fibrosis-independently predict EAR. These findings highlight distinct anatomical and electrophysiological risk domains and support substrate assessment with targeted endocardial completion in a staged workflow.