Left Atrial Intramyocardial Fat at Pulmonary Vein Reconnection Sites during Atrial Fibrillation Redo Ablation.

Abstract

Background and aims: Electrical reconnections between pulmonary veins (PVs) and the left atrium (LA) are frequently responsible for atrial fibrillation (AF) recurrences after pulmonary vein isolation (PVI). Multidetector computed tomography (MDCT)-derived images can be post-processed to detect intramyocardial fat (inFAT) by signal radiodensity thresholding. The role of inFAT on PV-LA reconnections remains unknown. The aim of this study was to analyze the relationship between inFAT localization at pre-procedural MDCT-derived inFAT maps from first AF ablation and PV-LA reconnections in patients with AF recurrence undergoing redo ablation.

Methods: We included 45 consecutive patients who underwent AF redo ablation presenting at least one PV-LA reconnection. First AF ablation preprocedural MDCT-derived data were post-processed with ADAS 3DTM to create 3D LA inFAT maps, that were loaded into CARTO3 navigation system and merged with the electroanatomical map for reconnection site analysis.

Results: In 103 out of 156 (66.0%) PV-LA reconnection points inFAT was identified in the 6mm diameter tag point depicted in the navigation system. When dividing the PVI line into standardized segments, those identified as containing PV-LA reconnection points (i.e. reconnection segments) exhibited significantly higher total inFAT volumes compared with non-reconnection segments (8.05±6.56 vs. 5.40±5.18 μL, p<0.001). Additionally, reconnection segments showed greater volumes of inFAT components, specifically dense inFAT (0.06±0.06 vs. 0.03±0.04 μL, p<0.001) and fat-myocardial admixture (7.98±6.52 vs. 5.37±5.16 μL, p<0.001).

Conclusion: InFAT is co-localized with two thirds of PV-LA reconnection points in patients undergoing AF redo ablation. Reconnection segments exhibit significantly higher inFAT volumes compared to non-reconnection segments. This proof-of-concept study suggests that inFAT may play a role in PV-LA electrical reconnections following PVI.