The Value of Ablation Parameter Indices for Predicting Mature Atrial Scar Formation in Humans: An In Vivo Assessment using Cardiac Magnetic Resonan…
Authors of this article are:
Chubb H Lal K Kiedrowicz R Karim R Williams SE Harrison J Whitaker J Wright M Razavi R O’Neill M.
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INTRODUCTION: The VisiTag module (CARTO3) provides an objective assessment of radiofrequency (RF) ablation parameters. This study aimed to determine the predictive value and optimal VisiTag threshold settings for prediction of gaps in mature atrial scar, as assessed non-invasively using cardiac magnetic resonance (CMR) imaging.METHODS: 24 subjects (11 paroxysmal AF) underwent first-time RF ablation with operators blinded to VisiTag data. 3D LGE CMR scans were performed at 3 months (1.3×1.3x4mm3 ). A survey of UK operators defined standard VisiTag settings (‘Force’ 8g, ‘Time’ 10seconds, ‘Percentage Time’ 50%, ‘Range’ 3mm, ‘Impedance’ and ‘Temperature’ ‘off’). Each ablation procedure was exported 27 times, varying single VisiTag parameters from default values. The presence of gaps in VisiTag markers (18 sectors) was assessed for each export and compared to gaps in CMR enhancement.RESULTS: At default settings, VisiTag gaps were specific (97.5%) but less sensitive (50.4%) for CMR gaps. Sensitivity improved at higher thresholds (89.2% at 20g, 85.6% at 30sec, 88.5% Impedance 10Ω, 92.8% Temperature 42°C), but with lower positive predictive value (42.3%, 42.7%, 41.1% and 37.7%, respectively, versus 90.9% at baseline). ‘Force’ thresholds demonstrated stable PPV from 2-8g (p=0.24), but a rapid fall at forces >10g. Binomial logistic regression model explained 41.7% of gaps (χ2(4)=148, p<0.0001), correctly classifying 82% of cases (specificity 94.9%, sensitivity 56.8%).CONCLUSION: Gaps in VisiTags predict gaps in CMR LGE enhancement with high specificity at default settings. Sensitivity may be improved using more stringent thresholds, but at the potential cost of unnecessary ablation, particularly when a force >10g is stipulated. This article is protected by copyright. All rights reserved.This article is protected by copyright. All rights reserved.
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This article is a good source of information and a good way to become familiar with topics such as: Atrial fibrillation;atrial fibrosis;cardiac magnetic resonance imaging;catheter ablation;structural remodeling.
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