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. 2025 Feb 5;27(2):euaf038.
doi: 10.1093/europace/euaf038.

Left atrial intramyocardial fat at pulmonary vein reconnection sites during atrial fibrillation redo ablation

Federico Landra  1   2 , Andrea Saglietto  1   3   4 , Giulio Falasconi  1   5 , Diego Penela  1   6 , David Soto-Iglesias  1 , Emanuele Curti  1   7 , Bruno Tonello  1 , Lucio Teresi  1   8 , Dario Turturiello  1 , Paula Franco-Ocaña  1 , Carlo Gigante  1   9 , Chiara Valeriano  1   10 , Claudio Capobianco  1 , Pietro Francia  1   11 , José Alderete  1 , Daniel Viveros  1 , Aldo Francisco Bellido  1 , Fatima Zaraket  1 , Julio Martí-Almor  1 , Matteo Cameli  2 , Antonio Berruezo  1
Affiliations

Left atrial intramyocardial fat at pulmonary vein reconnection sites during atrial fibrillation redo ablation

Federico Landra et al. Europace. .

Abstract

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 analyse 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 and results: We included 45 consecutive patients who underwent AF redo ablation presenting at least one PV-LA reconnection. First AF ablation pre-procedural MDCT-derived data were post-processed with ADAS 3D™ to create 3D LA inFAT maps, which were loaded into CARTO3 navigation system and merged with the electroanatomical map for reconnection site analysis. In 103 out of 156 (66.0%), PV-LA reconnection points inFAT was identified in the 6 mm 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: Intramyocardial fat 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.

Keywords: Atrial fibrillation; Catheter ablation; Intramyocardial fat; Pulmonary vein reconnection; Redo ablation.

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Conflict of interest statement

Conflict of interest: A.B. is stockholder of Galgo Medical. D.S.-I. and P.F.-O. are employees of Biosense Webster. All remaining authors have declared no conflicts of interest.

Figures

Graphical Abstract
Graphical Abstract
InFAT, intramyocardial fat; AF, atrial fibrillation; PV, pulmonary vein; LA, left atrium; MDCT, multidetector computed tomography; PVI, pulmonary vein isolation; AS, antero-superior segment; AC, antero-carinal segment; AI, antero-inferior segment; PI, postero-inferior segment; PC, postero-carinal segment; PS, postero-superior segment.
Figure 1
Figure 1
MDCT-derived 3D inFAT map. Septal view of a LA 3D inFAT map. Red areas correspond to dense inFAT (−194 to −50 HU), yellow-orange areas to fat-myocardial admixture (−50 to −5 HU), and blue areas do not harbour inFAT at all (>−5 HU). MDCT, multidetector computed tomography; inFAT, intramyocardial fat; LA, left atrial; HU, Hounsfield unit.
Figure 2
Figure 2
PVI line analysis. MDCT-derived 3D inFAT maps of the LA from different perspectives. A 6 mm wide band corresponding to PVI line trajectory was traced. Top-left panel: lateral–cranial view of the left PVI line; top-right panel: lateral–caudal view of the left PVI line; bottom-left panel: lateral–cranial view of the left PVI line; bottom-right panel: internal medial-to-lateral view of the left PVI line. MDCT, multidetector computed tomography; inFAT, intramyocardial fat; LA, left atrial; PVI, pulmonary vein isolation.
Figure 3
Figure 3
Procedural workflow. Pre-procedural MDCT scan of first AF ablations were post-processed. 3D inFAT maps were imported into the navigation system for PV-LA reconnection site analysis (identification of spatial colocalization between PV-LA reconnection points and inFAT). Also, PVI line was traced on 3D inFAT maps with the aim of quantifying the inFAT volume at each PVI line segment (total inFAT, dense inFAT, and fat-myocardial admixture). MDCT, multidetector computed tomography; AF, atrial fibrillation; LA, left atrium; inFAT, intramyocardial fat; PVI, pulmonary vein isolation.
Figure 4
Figure 4
Intramyocardial fat distribution at PVI line segments. First ablation MDCT-derived total inFAT volume distribution at various PVI line segments is depicted in a proportional manner (red ≥ 7.00 μL; orange ≥ 5.00 μL, yellow ≥ 3.00 μL, white < 3.00 μL). Both right PVs and left PVs show a higher amount of total inFAT at roof, antero-carinal, and antero-inferior segments. InFAT, intramyocardial fat; PVI, pulmonary vein isolation; MDCT, multidetector computed tomography; PV, pulmonary vein; AS, antero-superior segment; AC, antero-carinal segment; AI, antero-inferior segment; PI, postero-inferior segment; PC, postero-carinal segment; PS, postero-superior segment.
Figure 5
Figure 5
Total inFAT, dense inFAT, and fat-myocardial admixture volumes dot plots. Intramyocardial fat volumes comparison between reconnection segments and non-reconnection segments. Reconnection segments have significantly higher total inFAT, dense inFAT, and fat-myocardial admixture volumes compared to non-reconnection segments. InFAT, intramyocardial fat.
See this image and copyright information in PMC

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