Abstract
Although Ablation Index (AI)-guided ablation facilitates creation of lesions of consistent depth, pulmonary vein (PV) reconnection is still commonly observed after AI-guided pulmonary vein isolation (PVI). The present study aimed to investigate the impact of local left atrial wall thickness on the incidence of acute PV reconnection after AI-guided atrial fibrillation (AF) ablation. Seventy patients (63% paroxysmal AF, 67% male, mean age 63±8years) who underwent preprocedural CT imaging and AI-guided AF ablation were studied. Occurrence of acute PV reconnection after initial PVI was assessed after a 30-minute waiting period. Ablation procedures were retrospectively analyzed and each ablation circle was subdivided into 8 segments. Minimum AI, force-time integral, contact force, ablation duration, power, impedance drop and maximum interlesion distance were determined for each segment. PV antrum wall thickness was assessed for each segment on reconstructed CT images based on patient-specific thresholds in Hounsfield Units. Acute reconnection occurred in 27/1120 segments (2%, 15 anterior/roof, 12 posterior/inferior) in 19/140 ablation circles (14%). Reconnected segments were characterized by a greater local atrial wall thickness, both in anterior/roof (1.87±0.42 vs. 1.54±0.42mm; p<0.01) and posterior/inferior (1.43±0.20 vs. 1.16±0.22mm; p<0.01) segments. Minimum AI, force-time integral, contact force, ablation duration, power, impedance drop and maximum interlesion distance were not associated with acute reconnection. Local atrial wall thickness is associated with acute pulmonary vein reconnection after AI-guided PVI. Individualized AI targets based on local wall thickness may be of use to create transmural ablation lesions and prevent PV reconnection after PVI.
Highlights
Pulmonary vein (PV) reconnection is mainly due to nontransmural ablation [1], and is considered a major determinant of atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) [2]
The main findings are as follows: (1) marked regional variability in PV antral wall thickness was noted; (2) local wall thickness was associated with occurrence of acute PV. Reconnection, both in anterior/roof segments and posterior/inferior segments and (3) commonly used metrics of ablation lesion quality such as Ablation Index (AI), force–time integral (FTI), and impedance drop did not correlate with PV reconnection, whereas AI adjusted to wall thickness had predictive value for PV reconnection
We found that minimum AI adjusted to wall thickness was associated with acute PV reconnection, whereas minimum FTI and unadjusted minimum AI could not discriminate between segments with and without reconnection
Summary
Pulmonary vein (PV) reconnection is mainly due to nontransmural ablation [1], and is considered a major determinant of atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) [2]. AI correlated strongly with ablation lesion depth in a canine model [6], and was shown to predict PV reconnection in patients undergoing CF-guided PVI [5,7,8] Based on these findings, AI target values have been defined, ranging from 450 to 550 for anterior/roof segments and from 330 to 400 for posterior/inferior segments [9,10,11,12,13]. Minimum AI, forcetime integral, contact force, ablation duration, power, impedance drop and maximum interlesion distance were determined for each segment. Individualized AI targets based on local wall thickness may be of use to create transmural ablation lesions and prevent PV reconnection after PVI.
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