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Multiple groups have reported on the usefulness of ablating in atrial regions exhibiting abnormal electrograms during atrial fibrillation (AF). Still, previous studies have suggested that ablation outcomes are highly operator- and center-dependent. This study sought to evaluate a novel machine learning software algorithm named VX1 (Volta Medical), trained to adjudicate multipolar electrogram dispersion.This study was a prospective, multicentric, nonrandomized study conducted to assess the feasibility of generating VX1 dispersion maps. In 85 patients, 8 centers, and 17 operators, we compared the acute and long-term outcomes after ablation in regions exhibiting dispersion between primary and satellite centers. We also compared outcomes to a control group in which dispersion-guided ablation was performed visually by trained operators.The study population included 29% of long-standing persistent AF. AF termination occurred in 92% and 83% of the patients in primary and satellite centers, respectively, p = 0.31. The average rate of freedom from documented AF, with or without antiarrhythmic drugs (AADs), was 86% after a single procedure, and 89% after an average of 1.3 procedures per patient (p = 0.4). The rate of freedom from any documented atrial arrhythmia, with or without AADs, was 54% and 73% after a single or an average of 1.3 procedures per patient, respectively (p 0.001). No statistically significant differences between outcomes of the primary versus satellite centers were observed for one (p = 0.8) or multiple procedures (p = 0.4), or between outcomes of the entire study population versus the control group (p 0.2). Interestingly, intraprocedural AF termination and type of recurrent arrhythmia (i.e., AF vs. AT) appear to be predictors of the subsequent clinical course.VX1, an expertise-based artificial intelligence software solution, allowed for robust center-to-center standardization of acute and long-term ablation outcomes after electrogram-based ablation.

Introduction: During atrial fibrillation (AF) ablation, it is generally considered that atrial tachycardia (AT) episodes are a consequence of ablation. Objective: To investigate the spatial relationship between localized AT episodes and dispersion/ablation regions during persistent AF ablation procedures. Methods: We analyzed 72 consecutive patients who presented for an index persistent AF ablation procedure guided by the presence of spatiotemporal dispersion of multipolar electrograms. We characterized spontaneous or post-ablation ATs’ mechanism and location in regard to dispersion regions and ablation lesions. Results: In 72 consecutive patients admitted for persistent AF ablation, 128 ATs occurred in 62 patients (1.9 ± 1.1/patient). Seventeen ATs were recorded before any ablation. In a total of 100 ATs with elucidated mechanism, there were 58 localized sources and 42 macro-reentries. A large number of localized ATs arose from regions exhibiting dispersion during AF (n = 49, 84%). Importantly, these ATs’ locations were generally remote from the closest ablation lesion (n = 42, 72%). Conclusions: In patients undergoing a persistent AF ablation procedure guided by the presence of spatiotemporal dispersion of multipolar electrograms, localized ATs originate within dispersion regions but remotely from the closest ablation lesion. These results suggest that ATs represent a stabilized manifestation of co-existing AF drivers rather than ablation-induced arrhythmias.

Background The use of intracardiac electrograms to guide atrial fibrillation (AF) ablation has yielded conflicting results. Objectives The authors evaluated the usefulness of spatiotemporal dispersion, a visually recognizable electric footprint of AF drivers, for the ablation of all forms of AF. Methods The authors prospectively enrolled 105 patients admitted for AF ablation. AF was sequentially mapped in both atria with a 20-pole PentaRay catheter. The authors tagged and ablated only regions displaying electrogram dispersion during AF. Results were compared to a validation set in which a conventional ablation approach was used (pulmonary vein isolation/stepwise approach). To establish the mechanism underlying spatiotemporal dispersion of AF electrograms, the authors conducted realistic numerical simulations of AF drivers in a 2-dimensional model and optical mapping of ovine atrial scar-related AF. Results Ablation at dispersion areas terminated AF in 95% of the 105 patients. After ablation of 17 ± 10% of the left atrial surface and 18 months of follow-up, the atrial arrhythmia recurrence rate was 15% after 1.4 ± 0.5 procedures per patient versus 41% in the validation set after 1.5 ± 0.5 procedures per patient (arrhythmia free-survival: 85% vs. 59%; log-rank p Conclusions The clustering of intracardiac electrograms exhibiting spatiotemporal dispersion is indicative of AF drivers. Their ablation allows for a nonextensive and patient-tailored approach to AF ablation. (Substrate Ablation Guided by High Density Mapping in Atrial Fibrillation [SUBSTRATE HD]; NCT02093949)

Objectives This study sought to evaluate the impact of a complex fractionated atrial electrogram (CFAE)–guided ablation strategy on atrial fibrillation (AF) dynamics in patients with persistent AF. Background It is still unclear whether complete pulmonary vein isolation (PVI) is required or if the ablation of well-delineated pulmonary vein (PV) subregions could achieve similar outcomes in persistent AF. Methods CFAE-guided ablations were performed in 76 patients (65.2 ± 10 years of age) with persistent AF. In 47 patients, we measured mean PVs and left atrial appendage (LAA) cycle length (CL) values (PV-CL and LAA-CL), before ablation and before AF termination. We defined “active” PVs as PV-CL ≤ LAA-CL, “rapid fires” as PV-CL ≤80% of LAA-CL, and “PV-LAA CL gradient” as a significant CL difference between the 2 regions. Results AF termination (sinus rhythm [SR] or atrial tachycardia [AT] conversion) occurred in 92% and SR conversion in 75%. The radiofrequency time for AF termination and total radiofrequency time were 26 ± 25 min and 61.1 ± 21.6 min, respectively. Thirty of 47 patients had active PV (with 19 PV “rapid fires”). Ablation significantly increased median CL, both at PVs and LAA from 188 ms (interquartile range [IQR]: 161 to 210 ms) to 227.5 ms (IQR: 200 to 256 ms) (p Conclusions CFAE-guided ablation leads to a large decrease in PV frequency of activation, preceding AF termination. A PV modulation approach, rather than complete PVI, may be preferable for persistent AF.

The role of pulmonary veins (PVs) in persistent atrial fibrillation (AF) perpetuation appears less important than in paroxysmal AF. Electrogram-based substrate ablation is not widely performed as a stand-alone strategy.To evaluate PV activity in AF perpetuation and efficacy of our patient-tailored ablation strategy (electrogram-based substrate ablation with or without pulmonary vein isolation [PVI]).One hundred twenty-one patients with paroxysmal (n = 19; 15.7%), persistent (n = 77; 63.6%), or long-standing persistent (n = 25; 20.7%) AF underwent electrogram-based substrate ablation with AF termination end point: sinus rhythm or atrial tachycardia conversion. Before ablation, we classified PVs as "passive" if silent PV or if PV cycle length is greater than left atrial appendage cycle length. No PVI was performed in such cases.Passive PVs were observed in 52 of 121 patients (paroxysmal AF = 0%, persistent AF = 40%, and long-standing persistent AF = 76%; P.0001]). Substrate ablation terminated AF in 95.6% (sinus rhythm conversion in 80.2%). Compared with patients with active PVs, patients with passive PVs had longer AF sustained duration (19.1 ± 29.7 months vs 4.9 ± 11.1 months; P.0001), larger left atrial diameter (46.9 ± 7.3 mm vs 41.9 ± 6.0 mm; P = .0014), lower left ventricular ejection fraction (45.4% ± 13.5% vs 55.1% ± 9.4%; P.0001), and more often structural heart disease (57% vs 33%; P = .02). After a follow-up of 20.39 ± 11.23 months (1.6 procedures per patient), 82% were arrhythmia free with this strategy.PV activity during AF decreases with AF chronicity, left atrial dilatation, and left ventricular ejection fraction. Our patient-tailored ablation strategy without systematic PVI provides good results.

This study sought to evaluate the impact of a complex fractionated atrial electrogram (CFAE)-guided ablation strategy on atrial fibrillation (AF) dynamics in patients with persistent AF.It is still unclear whether complete pulmonary vein isolation (PVI) is required or if the ablation of well-delineated pulmonary vein (PV) subregions could achieve similar outcomes in persistent AF.CFAE-guided ablations were performed in 76 patients (65.2 ± 10 years of age) with persistent AF. In 47 patients, we measured mean PVs and left atrial appendage (LAA) cycle length (CL) values (PV-CL and LAA-CL), before ablation and before AF termination. We defined "active" PVs as PV-CL ≤ LAA-CL, "rapid fires" as PV-CL ≤80% of LAA-CL, and "PV-LAA CL gradient" as a significant CL difference between the 2 regions.AF termination (sinus rhythm [SR] or atrial tachycardia [AT] conversion) occurred in 92% and SR conversion in 75%. The radiofrequency time for AF termination and total radiofrequency time were 26 ± 25 min and 61.1 ± 21.6 min, respectively. Thirty of 47 patients had active PV (with 19 PV "rapid fires"). Ablation significantly increased median CL, both at PVs and LAA from 188 ms (interquartile range [IQR]: 161 to 210 ms) to 227.5 ms (IQR: 200 to 256 ms) (p 0.0001) and from 197 ms (IQR: 168 to 220 ms) to 224 ms (IQR: 193 to 250 ms) (p 0001), respectively. After ablation, PV-LAA CL gradients were withdrawn and all PV "rapid fires" were extinguished (without PVI). After 17.2 ± 10 months of follow-up and 1.61 ± 0.75 procedures, 86.3% and 73% of the patients were free from AF and from any arrhythmia (AF/AT), respectively.CFAE-guided ablation leads to a large decrease in PV frequency of activation, preceding AF termination. A PV modulation approach, rather than complete PVI, may be preferable for persistent AF.

Introduction: Multi-electrode electrogram temporal activation and fractionation have been used to localize atrial fibrillation (AF) drivers. Yet, the feasibility of a simplified “online” analysis and its usefulness to ablate AF remain to be investigated. Hypothesis: Evaluating a simplified “online” electrogram analysis approach designed to localize and ablate AF drivers. Methods: 105 patients undergoing AF ablation (77% with persistent AF, 3 centres) were prospectively enrolled. AF was first mapped in both atria with the 20-pole contact electrode catheter PentaRay® (Biosense Webster, Inc.) in order to identify regions with a temporal activation pattern compatible with the presence of rapidly rotating rotors. Specifically, regions with consecutive activations spanning the majority of the AF cycle length (including examples of rapid and continuously fractionated electrograms) were visually selected (“hot zone”).The endpoints were AF termination acutely, and freedom from long-term AF (single procedure). Off-line, electrogram cycle length values were compared between “hot” and “non-hot” regions and a numerical simulation of PentaRay-enabled unipolar recordings of a stable rotor driving AF was conducted Results: Visually selected “hot” regions located mostly in the left atrium (6.5 ±4.2/patient; ~70% of ”hot” regions). “Hot” regions were activated at a significantly shorter cycle length than “non-hot” regions (171.8 ± 4.8 vs. 193.0 ± 6.3 ms, p=0.01, N=20). 95.6% of the “hot regions” were automatically labelled CFAEs (automated analysis, Carto). However, 4.5±3.4 distinct CFAEs regions/patient were also labelled in “non-hot” regions. Ablation at “hot” regions terminated AF in 99/104 patients (95.2%), 46 [21-72] min after the 1st radiofrequency application within 20 [10-37] min of RF. Also, numerical simulations show that a simplified PentaRay®-enabled activation analysis is sufficient to distinguish rotor and non-rotor regions. After 9+3 [6-11], months of median [Q1-Q3] follow-up, 87 % were free from AF after 1 procedure and 53 % still under antiarrhythmic drugs. Conclusions: With this simplified “online” analysis, we could successfully localize rotor regions and perform efficient AF ablation. Clinical trial.gov: NCT02093949