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Background: Low voltage areas (LVAs) have been proposed as surrogate markers for left atrial (LA) scar. Correlation between voltages in sinus rhythm (SR) and atrial fibrillation (AF) have previously been measured via point-by-point analysis. We sought to compare LA voltage composition measured in SR to AF, utilizing a high-density automated voltage histogram analysis (VHA) tool in those undergoing pulmonary vein isolation (PVI) for persistent AF (PeAF)., Methods: We retrospectively analyzed patients with PeAF undergoing de novo PVI. Maps required ≥ 1,000 voltage points in each rhythm and had a standardized procedure (mapped in AF then remapped in SR post-PVI). We created six anatomical segments (AS) from each map: anterior, posterior, roof, floor, septal and lateral AS. These were analyzed by VHA, categorizing atrial LVAs into 10 voltage aliquots 0 - 0.5 mV. Data were analyzed using SPSS v.26., Results: We acquired 58,342 voltage points (n = 10 patients, mean age: 67 ± 13 years, three females). LVA burdens of ≤ 0.2 mV, designated as "severe LVAs", were comparable between most AS (except on the posterior wall) with good correlation. Mapped voltages between the ranges of 0.21 and 0.5 mV were labeled as "diseased LA tissue", and these were found significantly more in AF than SR. Significant differences were seen on the roof, anterior, posterior, and lateral AS., Conclusions: Diseased LA tissue (0.21 - 0.5 mV) burden is significantly higher in AF than SR, mainly in the anterior, roof, lateral, and posterior wall. LA "severe LVA" (≤ 0.2 mV) burden is comparable in both rhythms, except with respect to the posterior wall. Our findings suggest that mapping rhythm has less effect on the LA with voltages < 0.2 mV than 0.2 - 0.5 mV across all anatomical regions, excluding the posterior wall., Competing Interests: No conflict of interest to report., (Copyright 2023, Mannion et al.)

Background: Ablation index (AI) is a novel catheter-based parameter that has improved the outcome and safety of radiofrequency (RF) ablation of pulmonary vein isolations (PVIs). This index incorporates contact force (CF) (g), time (s), and power (W) parameters. The role of AI in redo ablations for persistent atrial fibrillation (peAF) has not been fully investigated. Hence, the impact of AI on the success of the redo PVI during the short-term follow-up period is the aim of this study., Methods: A retrospective analysis of 39 consecutive patients who underwent redo PVI ablations for peAF was carried out between January 2016 and December 2018. Target values for AI were 500 - 550 for anterior and roof and 400 - 380 for posterior and inferior regions. We compared outcomes between AI-guided and catheter CF ablations (i.e., forced time integral (FTI) of more than 400 g/s) during a follow-up of 24 months., Results: Pulmonary vein reconnections at redo procedure were similar in both groups (P = 0.1). AF free burden period was non-significant (mean 15.53 ± 2.4 months in AI group vs. 15.22 ± 1.9 months in CF group, P = 0.79) at 24 months. The AI group demonstrated greater numbers of patients for whom anti-arrhythmic therapy could be de-escalated over 1 year (n = 11 (65%) in AI vs. n = 6 (27%) in CF, P = 0.02). Fewer patients underwent escalation of their anti-arrhythmic therapy (n = 2 (12%) in AI vs. n = 7 (32%) in CF, P = 0.15). The AI group trended towards a shorter procedure time (111.6 ± 27 min) compared to the CF group (133 ± 40 min) (P = 0.06). Other procedural details were comparable., Conclusion: Redo PVI interventions using AI lead to a significant de-escalation in medication during follow-up. Procedure time and radiation dose using AI tends to be shorter. Both techniques are safe with minimal complications., Competing Interests: Limited financial support from J&J to cover the publication fee of the manuscript., (Copyright 2022, Lennon et al.)