Catheter Ablation -> Atrial Fibrillation & Atrial Flutter: -> Ablation Techniques D-PO01 - Featured Poster Session (ID 11) Poster

Abstract

Background: atrial wall changes on cardiac magnetic resonance (CMR) after catheter ablation have been extensively described with thermal methods (TH), but never after non-thermal pulsed field ablation (PFA).
Objective: to characterize acute and chronic changes in LA wall tissue characteristics on CMR after PFA.
Methods: CMR was performed before, acutely (<3h) and 3 months post-ablation in 41 pts with paroxysmal AF undergoing PVI with PFA (N=19, Farapulse®) or TH methods (N=22, 15 RF, 7 cryo). Tissue changes on late gadolinium enhanced (LGE) and T2 imaging were quantified. All pts ablated with PFA underwent prospective EP remap at 3 months.
Results: LA volume and baseline fibrosis were similar between groups. Acutely, LGE was larger after PFA than TH ablation (+60%, P<0.001). Dark zones within LGE suggestive of intramural no-flow or hemorrhage were found in 100% of TH pts and in no PFA pts. Acute edema on T2 imaging was lower after PFA (-17%, P=0.002). In contrast to acute findings, chronic scar on 3 months LGE was much lower after PFA (P<0.001), as most of the acute LGE had reversed (-69% in PFA vs -20% in TH, P<0.001). This did not match EP findings at 3 months, with all PFA patients showing durable lesions by voltage mapping.
Conclusion: PFA induces broader acute LA lesions characterized by intense LGE, likely due to cell membrane disruption leading to large extracellular expansion. As opposed to TH methods, PFA does not induce intramural hemorrhage or microvascular dysfunction acutely, and does not translate into similar chronic scar burden. The reversibility of LGE at the chronic stage may be explained by the absence of collagen synthesis or interstitial expansion and preserved wash-out kinetics.

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