Left Atrial Posterior Wall Functional Remodeling in Paroxysmal and Persistent Atrial Fibrillation. A Pilot Study

The left atrial posterior wall (LAPW) is often targeted in atrial fibrillation (AF) ablation due to its shared properties with pulmonary veins. However, substrate-guided approaches using structural markers have shown inconsistent results. We investigated posterior wall conduction time (PWCT) as a novel and functional marker of LAPW remodeling in AF patients.

In our pilot study, 40 patients undergoing first-time AF ablation (20 paroxysmal, 20 persistent AF) were included. AF cycle length (AF CL), PW linear conduction, PW conduction area (PWCA) and PWCT were evaluated on electroanatomical mapping at different pacing CLs. Major decremental PWCT was defined as PWCT increase ≥ 17% at 400 ms compared to 600 ms.

Persistent AF patients had a larger posterior wall area (PWA; 20.4 ± 5.2 vs. 16.8 ± 4.9 cm², p = 0.033), greater low voltage area (LVA; 16.5 ± 25.8% vs. 6.1 ± 19.8%, p = 0.044) and shorter left atrial appendage AF CLs (shortest AF CL 146.2 ± 36.3 vs. 179.1 ± 37.1 ms, p = 0.012) than paroxysmal AF patients. PWCT was numerically longer in persistent AF, with major ΔPWCT observed exclusively in 6 persistent AF patients. In this subgroup, PWCA was reduced at each 10 ms increment during 400 ms pacing, a finding not observed in non-major ΔPWCT subgroup. Major ΔPWCT did not correlate with PWA size, LVA, or AF CL.

PWCT may represent a novel functional biomarker of LAPW remodeling, independent of structural changes, potentially identifying patients who may benefit from targeted LAPW ablation. Further studies are needed to validate PWCT as a guide for personalized AF ablation.