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Background: A novel lattice tip ablation catheter that can toggle between radiofrequency and pulsed-field energy is able to perform not only pulmonary vein isolation, but also linear lesions under general anesthesia (GA)., Objective: We aimed to evaluate the concerns associated with the use of deep sedation and the clinical data related to linear ablation., Methods: Clinical data from two Germany high-volume atrial fibrillation (AF) centers were collected. The objectives of this study are to confirm the feasibility and safety of linear lesion ablation using the lattice tip catheter without GA. Acute procedural and short-term follow-up data were collected., Results: This study included 55 patients who underwent AF ablation (15 with GA vs 40 with deep sedation) including linear lesion ablation for atrial tachyarrhythmia using a lattice tip catheter. Bidirectional block of linear lesions was achieved in 21 of 21 linear lesions in the GA and in 74 of 76 (97%) linear lesions in the deep sedation group (P = 1.000) including roof line in 41 of 41 (100%), posterior wall isolation in 4 of 4 (100%), anterior mitral isthmus (MI) line in 5 of 5 (100%) vs 24 of 25 (96%), posterior MI line in 1 of 1 (100%) vs 4 of 5 (80%), cavotricuspid isthmus line in 15 of 15 (100%), and 1 left atrial appendage isolation. The overall incidence rate of complications was 1.8% (1 cardiac tamponade). There was no other procedural related complication., Conclusion: This preliminary clinical study demonstrates feasibility and safety of bidirectional block of linear lesions using a lattice tip catheter under deep sedation. Need to toggle between energy sources was low., Competing Interests: Disclosures Dr Schmidt is a consultant for—and has received honoraria as well as research funding from—Abbott, Medtronic, Boston Scientific, and Biosense Webster. Dr Bordignon has received honoraria from Medtronic and Biosense Webster. Dr Metzner is a consultant for—and has received honoraria from—Abbott, Medtronic, Boston Scientific, and Biosense Webster. Dr Chun is a consultant for—and has received honoraria as well as research funding from—Abbott, Medtronic, Boston Scientific, and Biosense Webster. The other authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background Recurrent perimitral atrial tachycardia (AT) is a challenging arrhythmia and is frequently encountered in the context of atrial fibrillation (AF) ablation. Objective The purpose of this study was to investigate the clinical characteristics and the procedural and clinical outcomes in patients with recurrent perimitral atrial tachycardia (PMAT) after AF ablation. Methods Among 520 consecutive ablation procedures for recurrent AT/AF after AF ablation, 40 procedures (patients) were performed for clinically recurrent PMAT 12.1 ± 13.6 months after the last procedure (total 2.2 ± 1.3 procedures). Previously, mitral isthmus (MI) linear ablation was performed in 26 of 40 procedures, including 13 procedures with complete block and 13 with 159.0 ± 23.0 ms of conduction delay without block. As a reference group, conduction delay was evaluated in 55 patients with incomplete MI block and absence of spontaneous PMAT during the follow-up period. Results Recurrent PMATs were terminated by MI linear ablation in 26 of 40 patients. Bidirectional block across the MI and anterior line joining the mitral annulus and left atrial roof was achieved in 33 (82.5%) and 2 (5%) patients, respectively. At mean follow-up of 26.7 ± 14.5 months, 2 patients (5%) underwent reablation for spontaneously recurrent PMAT. At 12 months after the ablation procedure for PMAT, 73.5% of the patients were free from AT/AF. Conduction delay >149 ms predicted the occurrence of spontaneous PMAT with 80.0% sensitivity and 87.3% specificity. Conclusion PMAT can recur even after successful bidirectional MI linear block. Substantial conduction delay without block across the MI from a previous procedure(s) could predispose to recurrent PMAT. Although most clinical PMATs can be successfully treated by catheter ablation, very late recurrence is possible. [ABSTRACT FROM AUTHOR]

Background: While macroreentrant atrial tachycardias (ATs) have been reasonably well described, little is known about small reentrant circuits. Objective: To compare characteristics of large and small reentrant circuits after ablation of persistent atrial fibrillation. Methods: Seventy-seven patients (age 61±10 years; left atrium 46±6 mm; ejection fraction 0.52±0.13) underwent a procedure for postablation AT. The p-wave duration, circuit size, electrogram characteristics, and conduction velocity were determined. Results: AT was due to macroreentry in 62 (80%) patients, a small reentrant circuit in 13 (17%), and a focal mechanism in 2 (3%). The p-wave duration during small reentrant ATs was shorter than that during macroreentry (174±12 ms vs 226±22 ms; P<.0001). The duration of fractionated electrograms at the critical site was longer in small vs large circuits (167±43 ms vs 98±38 ms, respectively; P<.0001) and accounted for a greater percentage of the tachycardia cycle length (59%±18% vs 38%±14%, respectively; P<.0001). The mean diameters of macroreentrant and small reentrant circuits were 44±7 and 26±11 mm, respectively (P<.0001). The mean conduction velocity along the small circuits was lower (0.5±0.2 m/s vs 1.2±0.3 m/s; P<.0001). Catheter ablation eliminated the AT in all 77 patients. Conclusions: AT due to a small reentrant circuit after ablation of atrial fibrillation may be distinguished from macroreentry by a shorter p-wave duration and the presence of long-duration electrograms at the critical site owing to extremely slow conduction. These features may aid the clinician in the mapping of postablation ATs. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the feasibility and outcome of ablation to transect the anterior left atrium (LA) in patients with atrial fibrillation (AF).Background: While the Maze procedure is effective in maintaining sinus rhythm in patients with AF, it is associated with significant morbidity. This prospective clinical study evaluates the feasibility and consequences of limited LA linear ablation to transect the anterior LA in patients with AF.Methods: Twenty-four patients (51.2 +/- 7.3 years) with paroxysmal (n = 16) or chronic (n = 8) AF resistant to pulmonary vein (PV) isolation were studied. To transect the anterior LA, linear ablation was performed joining the superior PVs; this line was then connected to the anterior mitral annulus. Pulmonary vein isolation and cavotricuspid isthmus ablation were performed in all cases. Ablation was performed using an irrigated catheter with the endpoint of achieving complete linear block demonstrated by online double potentials, differential pacing techniques, and an activation detour.Results: Of 20 patients in AF prior to linear ablation, arrhythmia terminated in 12 (60%), including half the patients with chronic AF, during ablation. Despite repeated ablation, complete linear block was achieved in only 14 of 24 patients (58%). Complete linear conduction block resulted in an activation detour around the mitral annulus and PVs with a delay of 158 +/- 30 ms (P = .0001), significantly delayed activation of the lateral LA with prolongation of P-wave duration (P = .002), and characteristic change in P-wave morphology during sinus rhythm (P = .002). Of the 14 with anterior LA transection, 4 (29%) have had regular atrial tachycardias due to macroreentry through recovered gaps. Nine of these 14 (64%) have remained arrhythmia-free without antiarrhythmics compared to 3 of 10 (30%) with incomplete block at 28 +/- 4 months following their last procedure (P = .2).Conclusions: This study demonstrates the feasibility of catheter ablation to transect the anterior LA in humans. While being effective in the termination of AF, this configuration of linear lesions is technically challenging to complete, results in significant delayed LA activation, and is associated with modest long-term arrhythmia suppression. [ABSTRACT FROM AUTHOR]