Posterior Mitral Isthmus Research Articles

Feasibility of atrial linear ablation using a lattice tip catheter that toggles between radiofrequency and pulsed-field energy under deep sedation

BackgroundA 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). ObjectiveWe aimed to evaluate the concerns associated with the use of deep sedation and the clinical data related to linear ablation. MethodsClinical 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. ResultsThis 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. ConclusionThis 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.

Evaluation of posterior mitral isthmus ablation in the absence of a vein of Marshall.

Achieving acute and durable mitral isthmus (MI) block remains challenging using radiofrequency (RF) catheter ablation alone. Vein of Marshall (VoM) ethanolization results in chemical damage along the MI resulting in the creation of a durable transmural lesion with a very high rate of procedural block. However, no studies have systematically assessed the efficacy of MI ablation alone when no anatomical VoM is present. Thirty seven patients without VoM evidenced after careful angiographic examination were included. Ablation parameters and result were compared with a matched control group in whom the posterior MI line was performed without assessing the presence of the VoM. Mitral isthmus block was achieved in 36 out of 37 patients without VoM (97%), with endocardial ablation only in 5/37 (14%) and combined endocardial and coronary sinus ablation in 32/37 patients (86%). There was a significant difference in the occurrence of block between patients without a VoM and the control group (97.3% vs. 65% respectively, P < 0.01), with a trend towards less needed RF {26 [interquartile range (IQR) 20-38] vs. 29 [IQR 19-40] tags [P = 0.8], 611 [IQR 443-805] vs. 746 [IQR 484-1193] seconds [P = 0.08]}. The absence of a VoM is associated with a very high rate of procedural block during posterior MI ablation. The higher rate of MI block in this specific population would also suggest the crucial role of the VoM (when present) in resistant MI block.

Preliminary real-world experience on mitral isthmus ablation with a novel catheter that toggles between radiofrequency and pulsed field ablation

Abstract Background The mitral isthmus (MI) is frequently targeted during the ablation of persistent atrial fibrillation (AF). Nevertheless, achieving a complete bidirectional MI block using radiofrequency (RF) is often technically challenging and time-consuming1,2. Previously, we described a fluoroscopy-guided technique to achieve MI block using a penta-spline pulsed field ablation (PFA) catheter3. Recently, a new catheter was introduced, which toggles between RF and PFA and is integrated into a 3D mapping system, thus supposedly facilitating its use for the ablation of extra-pulmonary vein structures4. Purpose To describe the acute efficacy and procedural features of the first cases of posterior MI ablation performed with the toggling catheter at two centers. Methods We collected and reviewed demographic, clinical and procedural features of all patients who underwent ablation of the posterior MI at our centers between September and October 2023. Ablation of the MI was performed with either RF or PFA according to operator’s discretion. Bidirectional MI block was validated through activation mapping and differential pacing. Results During the study period, 44 patients were treated with the toggling catheter. Out of them, 16 patients (aged 68.3±10.1 years; 29% females) underwent posterior MI ablation for persistent AF, in addition to PVI and posterior wall isolation. Mean history of AF was 29.8±34.5 months and mean LA volume 135.6±54.9 ml. Skin-to-skin procedural time (93 minutes, IQR 64-112), LA mapping time (9.0 min, IQR 7.3-12.1) and time required for MI ablation (4.0 min, IQR 3.3-6.5) were remarkably short. In PFA-treated patients (10 cases), first-pass MI block was achieved in 8 (80%), with 16 (IQR 12-22) applications; none of these patients required RF touch-up. In the remaining 6 RF-treated patients, first-pass MI block was achieved in 3 (50%) patients with 8 (IQR 6-13) applications. Additional PFA applications (median 3, IQR 2-5) on the most venous portion of the MI were required in all RF-treated patients. In the 5 patients in whom bidirectional block could not be achieved at first-pass, remapping and touch-up application time were 2.6 (IQR 2.6- 6.3) and 2.0 (IQR 0.8-5.2) minutes, respectively. Eventually, bidirectional MI block was achieved in 16/16 (100%) patients by the end of the procedure. Importantly, no patients in the entire cohort experienced complications such as coronary artery spasm or clinically significant pericardial effusion. Conclusions Several observations can be made on this first real-world experience on posterior MI ablation with the toggling catheter: first, acute safety and efficacy in achieving a bidirectional MI block are high with both PFA and RF; secondly, patients undergoing RF ablation often require additional PFA applications on the venous segment of the MI; lastly, the time required to achieve MI block is remarkably short even when remapping and touch-up applications are needed.Figure 1Figure 2

Impact of additional pulsed field ablation in unsuccessful radiofrequency linear lesions -acute and chronic data

Abstract Background Performing linear ablation such as roof line, inferior line in the posterior part of LA and posterior mitral isthmus (MI) line in addition to PVI is one of the strategies for treating persistent atrial fibrillation. However, remnant conduction or reconnection in the lines is linked with atrial arrhythmia recurrence, either AF or AT. Radiofrequency ablation (RFA) is often unsuccessful achieving durable linear ablation. It is not yet well known whether using pulsed field ablation (PFA) would be superior in achieving complete linear lesions. Purpose We sought to evaluate the benefit of using PFA in unsuccessful RF ablation linear lesions. Methods We studied 17 patients that underwent redo procedures due to atrial arrhythmia recurrence. All of them underwent PFA (using a pentaspline PFA catheter) ablation lines due to previous unsuccessful RF ablation, either due to remnant conduction in the line or to reconnection of the line. Lines of block were evaluated based on activation mapping and differential pacing maneuvers close to the lines. Results We conducted 16 dome-posterior lines and 6 posterolateral mitral isthmus lines using PFA after unsuccessful RF ablation linear lesions. PFA was performed after several unsuccessful procedure, 1.3±0.4 for the roof line, 1.3±0.5 for the postero-inferior line and 1.7±0.9 for the MI line. In 4 out of 6 pts with MI isthmus ablation using PFA ethanol injection within vein of Marshall (Et-VOM) was conducted in a previous procedure and in 4 out of 6 patients with MI isthmus RF ablation within coronary sinus (CS) was performed in a previous procedure. Specifically, for the dome-posterior line, 2 patients underwent PFA deliveries only at the gap region in the posterior LA and in other 14 cases, PFA deliveries were performed at 3.2±0.8 sites of the posterior wall between LPV and RPV. We used a total of 15.5±4.6 PFA deliveries to complete the dome-posterior line. Dome-posterior line bidirectional block based on activation mapping and differential pacing maneuvers was achieved in all cases (16/16, 100%) after PFA. For the MI line, we performed a total of 11.8±2.3 application deliveries at 2.5±0.5 sites in the MI region. Posterior MI line bidirectional block based on activation mapping and differential pacing maneuvers was achieved in 5 out of 6 patients (83.3%). In one case additional Et-VOM was needed to achieve MI block. There was no AT/AF recurrence in all these 17 patients. Conclusion PFA treatment seems promising to back-up RF failed linear lesions. But we cannot exclude that it is in fact the combination of the 2 energies that was successful in those resistant cases.

Pulsed field ablation for atrial fibrillation: efficacy, safety and lesion durability in patients with recurrences

Abstract Background Initial findings from feasibility studies regarding pulsed field ablation (PFA) for atrial fibrillation (AF) indicated substantial efficacy and safety of the procedure, including high rates of lesion durability upon systematic remapping. However, data regarding PFA for AF in real-life settings remains scarce. Objective This pooled analysis was conducted to provide insights into PFA’s practical performance and safety profile in real-life settings, as well as information regarding lesion durability in patients with arrhythmia recurrences. Methods MEDLINE/EMBASE databases were searched up to August 31, 2023 for studies including patients undergoing catheter ablation for AF using PFA. Independent searches were performed by 2 investigators (K.B. and K.V.). Feasibility studies, first-in-human studies, small studies with population overlap, and those with a follow-up duration shorter than one year were excluded from the analysis. Authors were contacted for missing information or to confirm the absence of population overlap. Two investigators (K.B. and K.V.) independently extracted data from studies meeting inclusion criteria. Any discrepancies were resolved by a third experienced reviewer. Results We assessed for relevance a total of 952 references. Five studies met the inclusion criteria (comprising of 1 randomized trial, 2 single arm prospective trials, and 2 post-market registries), with a combined cohort of 2,359 patients who underwent PFA for AF. The pooled rate of acute PVI was 99.6% (95%CI 99.2-99.8, I2:7%). The pooled one-year rates of freedom from atrial arrhythmia for individuals with paroxysmal or persistent AF were 79.5% (95%CI 75.7-83.1, I2:70%) and 67.5% (95%CI 60.9-73.7, I2:60%), respectively. Among patients who underwent repeat catheter ablation for AF recurrences (n=197), the pooled rate of durable PVI per patient was 48.9% (95%CI 30.4-67.7, I2:71%), while durable PVI per vein was 74.1% (95%CI 65.1-82.2, I2: 75%). Incidence of overall complications and serious procedure-related complications were 1.8% (95% CI: 0.2-4.8, I2: 92%) and 0.9% (95% CI: 0.3-1.7, I2:59%), respectively. The most prevalent complication types were access site complications (48.6%), pericardial effusions/tamponades (24.8%) and stroke/transient ischemic attack (9.5%). No esophageal damage or PV stenosis were reported . There was one case of persistent phrenic nerve palsy and two cases of reversible coronary spasm (during ablation along the posterior mitral isthmus, and during PVI, both resolving with intracoronary nitroglycerin). Conclusion This pooled analysis confirms that catheter ablation of atrial fibrillation using pulsed field ablation is associated with high rates of atrial arrhythmia-free survival at one year while maintaining low rates of procedure-related complications. Durable pulmonary vein isolation is observed in approximately half of the patients undergoing a repeat procedure for atrial fibrillation recurrence.

Efficacy and Safety Ablation Index-Guided High-Energy Linear Ablation for Persistent Atrial Fibrillation: PVI Plus Linear Ablation of Mitral Isthmus and Posterior Box Isolation.

For patients with persistent atrial fibrillation (AF), whether linear ablation should be performed remains controversial, and the efficacy and safety for ablation index (AI)-guided high-energy linear ablation of mitral isthmus (MI) and left atrial (LA) posterior box isolation is still unclear. The aims of this study were to assess the feasibility and clinical success rate of pulmonary veins isolation (PVI) combined with linear ablation of LA roof and posterior inferior (posterior wall isolation) and MI compare with the PVI-alone method in patients of persistent AF. 362 consecutive persistent AF patients were enrolled from two electrophysiology centers. A total of 200 cases were in PVI-plus group and 162 cases were in PVI-alone group. The PVI-alone group received wide circumferential isolation of both ipsilateral pulmonary veins. PVI combined with linear ablation of left atrial posterior wall isolation (LAPWI)and MI were performed in the PVI-plus group. The primary study end point was the first recurrence of an atrial arrhythmia. After 24 months, freedom from the primary endpoint was achieved in 73.5% of the patients in the PVI-plus group and 62.5% in the PVI-alone group (hazard ratio = 0.62, 95% confidence interval: 0.43-0.91, log rank p = 0.012). The procedure-related complication rates were 2.5% in PVI-plus group and 1.9% in PVI-alone group (p = 0.808). In this study, the ablation strategy of ablation (PVI plus linear ablation of mitral isthmus and posterior box isolation) was feasible and safe for persistent AF patients. Compared with the PVI-alone method, it improved outcomes in patients with persistent AF.

Strategy for repeat procedures in patients with persistent atrial fibrillation: Systematic linear ablation with adjunctive ethanol infusion into the vein of Marshall versus electrophysiology-guided ablation.

The optimal strategy after a failed ablation for persistent atrial fibrillation (perAF) is unknown. This study evaluated the value of an anatomically guided strategy using a systematic set of linear lesions with adjunctive ethanol infusion into the vein of Marshall (Et-VOM) in patients referred for second perAF ablation procedures. Patients with perAF who underwent a second procedure were grouped according to the two strategies. The first strategy was an anatomically guided approach using systematic linear ablation with adjunctive Et-VOM, with bidirectional blocks at the posterior mitral isthmus (MI), roof, and cavotricuspid isthmus (CTI) as the procedural endpoint (Group I). The second one was an electrophysiology-guided strategy, with atrial tachyarrhythmia termination as the procedural endpoint (Group II). Arrhythmia behavior during the procedure guided the ablation strategy. Groups I and II consisted of 96 patients (65 ± 9 years; 71 men) and 102 patients (63 ± 10 years; 83 men), respectively. Baseline characteristics were comparable. In Group I, Et-VOM was successfully performed in 91/96 (95%), and procedural endpoint (bidirectional block across all three anatomical lines) was achieved in 89/96 (93%). In Group II, procedural endpoint (atrial tachyarrhythmia termination) was achieved in 80/102 (78%). One-year follow-up demonstrated Group I (21/96 [22%]) experienced less recurrence compared to Group II (38/102 [37%], Log-rank p = .01). This was driven by lower AT recurrence in Group I (Group I: 10/96 [10%] vs. Group II: 29/102 [28%]; p = .002). Anatomically guided strategy with adjunctive Et-VOM is superior to an electrophysiology-guided strategy for second procedures in patients with perAF at 1-year follow-up.

Atrial Fibrillation Ablation Using Vein of Marshall Ethanol Infusion.

Catheter ablation has become a cornerstone treatment for atrial fibrillation (AF). Pulmonary vein isolation is the accepted approach for paroxysmal AF ablation, but it is less effective for persistent AF. The vein of Marshall (VOM) is located in the epicardial left atrium and can be a source of AF triggers as well as a tract for autonomic nerves. It directly communicates with the underlying myocardium, including the left atrial ridge and the posterior mitral isthmus. This review discusses the latest evidence regarding the mechanisms, procedural aspects, and outcomes of VOM ethanol infusion when used as an adjunct to pulmonary vein isolation in patients with persistent AF.

Evaluation of left atrial linear ablation using contiguous and optimized radiofrequency lesions: the ALINE study.

Achieving block across linear lesions is challenging. We prospectively evaluated radiofrequency (RF) linear ablation at the roof and mitral isthmus (MI) using point-by-point contiguous and optimized RF lesions. Forty-one consecutive patients with symptomatic persistent AF underwent stepwise contact force (CF)-guided catheter ablation during ongoing AF. A single linear set of RF lesions was delivered at the roof and posterior MI according to the 'Atrial LINEar' (ALINE) criteria, i.e. point-by-point RF delivery (up to 35 W) respecting strict criteria of contiguity (inter-lesion distance ≤ 6 mm) and indirect lesion depth assessment (ablation index ≥550). We assessed the incidence of bidirectional block across both lines only after restoration of sinus rhythm. After a median RF time of 7 min [interquartile range (IQR) 5-9], first-pass block across roof lines was observed in 38 of 41 (93%) patients. Final bidirectional roof block was achieved in 40 of 41 (98%) patients. First-pass block was observed in 8 of 35 (23%) MI lines, after a median RF time of 8 min (IQR 7-12). Additional endo- and epicardial (54% of patients) RF applications resulted in final bidirectional MI block in 28 of 35 (80%) patients. During a median follow-up of 396 (IQR 310-442) days, 12 patients underwent repeat procedures, with conduction recovery in 4 of 12 and 5 of 10 previously blocked roof lines and MI lines, respectively. No complications occurred. Anatomical linear ablation using contiguous and optimized RF lesions results in a high rate of first-pass block at the roof but not at the MI. Due to its complex 3D architecture, the MI frequently requires additional endo- and epicardial RF lesions to be blocked.