Posterior Wall Isolation Research Articles

Temporal Trends and Lesion Sets for Persistent Atrial Fibrillation Ablation: A Meta-Analysis With Trial Sequential Analysis and Meta-Regression.

Ablation for persistent atrial fibrillation (PsAF) has been performed for over 20 years, although success rates have remained modest. Several adjunctive lesion sets have been studied but none have become standard of practice. We sought to describe how the efficacy of ablation for PsAF has evolved in this time period with a focus on the effect of adjunctive ablation strategies. Databases were searched for prospective studies of PsAF ablation. We performed meta-regression and trial sequential analysis. A total of 99 studies (15 424 patients) were included. Ablation for PsAF achieved the primary outcome (freedom of atrial fibrillation/atrial tachycardia rate at 12 months follow-up) in 48.2% (5% CI, 44.0-52.3). Meta-regression showed freedom from atrial arrhythmia at 12 months has improved over time, while procedure time and fluoroscopy time have significantly reduced. Through the use of cumulative meta-analyses and trial sequential analysis, we show that some ablation strategies may initially seem promising, but after several randomized controlled trials may be found to be ineffective. Trial sequential analysis showed that complex fractionated atrial electrogram ablation is ineffective and further study of this treatment would be futile, while posterior wall isolation currently does not have sufficient evidence for routine use in PsAF ablation. Overall success rates from PsAF ablation and procedure/fluoroscopy times have improved over time. However, no adjunctive lesion set, in addition to pulmonary vein isolation, has been conclusively demonstrated to be beneficial. Through the use of trial sequential analysis, we highlight the importance of adequately powered randomized controlled trials, to avoid reaching premature conclusions, before widespread adoption of novel therapies.

High-Power Short-Duration Lesion Index-Guided Posterior Wall Isolation beyond Pulmonary Vein Isolation for Persistent Atrial Fibrillation.

Background: High-power short-duration (HPSD) radiofrequency (RF) ablation has been adopted to improve atrial fibrillation (AF) ablation. Although the role of HPSD is well-established in pulmonary vein isolation (PVI), fewer data have assessed the impact of HPSD when addressing extra-pulmonary veins (PVs) targets. Therefore, this study aims to determine the safety, effectiveness, and acute outcomes of HPSD lesion index (LSI)-guided posterior wall isolation (PWI) in addition to PVI as an initial strategy in persistent atrial fibrillation (Pe-AF). Methods: Consecutive patients who underwent ablation of Pe-AF in our center between August 2021 and January 2022 were retrospectively enrolled. All patients' ablation strategy was PVI plus PWI using HPSD LSI-guided isolation. RF parameters included 50 W targeting LSI values of ≥5 on the anterior part of the PVs and anterior roofline and ≥4 for the posterior PVs aspect, bottom line, and within the posterior wall (PW). We compared the LSI values with and without acute conduction gaps after the initial first-pass PWI. Left atrial mapping was performed with the EnSite X mapping system and a high-density multipolar Grid-shaped mapping catheter. We compared the procedural characteristics using HPSD (n = 35) vs. a control group (n = 46). Results: Thirty-five consecutive patients were included in the study. PWI on top of PVI was achieved in all cases in the HPSD group. First-pass PVI was achieved in 93.3% of PVs (n = 126/135). First-pass roofline block was obtained in most patients (n = 31, 88.5%), while first-pass block of the bottom line was only achieved in 51.4% (n = 18). There were no significant differences compared to the control group; first-pass PVI was achieved in 94.9% of PVs (n = 169/178), first-pass roofline block in 89.1%, and bottom-line in 45.6% of patients. To achieve complete PWI with HPSD, scattered RF applications within the PW were necessary. No electrical reconnection of the PW was found after adenosine administration and the waiting period. The procedure and RF times were significantly shorter in the HPSD group compared to the control group, with values of 116.2 ± 10.9 vs. 144.5 ± 11.3 min, and 19.8 ± 3.6 vs. 26.3 ± 6.4 min, respectively, p < 0.001. Fluoroscopy time was comparable between both groups. No procedural complications were observed. At the 12-month follow-up, 71.4% of patients remained free from AF, with no differences between the groups. Conclusions: HPSD LSI-guided PWI on top of PVI seems effective and safe. Compared to a control group, HPSD is associated with similar rates of first-pass PWI and PVI but with a shorter procedural and RF time.

Adjunct posterior wall isolation reduces the recurrence of atrial fibrillation in patients undergoing cryoballoon ablation: A systematic review and meta-analysis.

Recurrence rates of atrial fibrillation (AF) remain high even after complete wide area circumferential pulmonary vein isolation (PVI). In recent years adjunct posterior wall isolation (PWI) has been performed in patients with more persistent forms of AF but the benefits remain unclear. The objective of this meta-analysis was to evaluate the efficacy of adjunct posterior wall isolation in reducing recurrence rates of AF using cryoballoon ablation (CBA). We searched PubMed, Google Scholar, Clinicaltrials.gov and Cochrane CENTRAL. We included studies comparing PVI to PVI + PWI in patients with either persistent or paroxysmal AF (PAF) undergoing CBA. After data extraction and quality assessment of the studies, we assessed recurrence rates of atrial tachy-arrhythmias (AF, atrial flutter, and atrial tachycardia) as well as total ablation time and procedural adverse events. Risk ratio (RR), mean difference (MD), and 95% confidence interval (CI) were calculated using Review Manager. Concomitant PWI exhibited a substantial reduction in the risk of AF recurrence (RR: 0.51; 95% CI: 0.42-0.63, p < .00001), as well as all atrial arrhythmias (RR: 0.58; 95% CI: 0.49-0.68, p < .00001). On subgroup analysis, in patients with only PAF, adjunct PWI resulted in significant reduction in recurrence risk of AF (RR: 0.56; 95% CI: 0.41-0.76, p = .0002) as well. There was no significant difference in adverse events between both groups (RR: 0.90; 95% CI: 0.44-1.86; p = .78), whereas total ablation time was significantly increased in PVI + PWI group (MD: 21.75; 95% CI: 11.13-32.37, p < .0001). Adjunct PWI when compared to PVI alone decreases recurrence rates of atrial fibrillation after CBA of patients with persistent as well as paroxysmal atrial fibrillation.

Safety and Effectiveness of Adjunctive Posterior Wall Isolation in Atrial Fibrillation Patients: An Updated Meta-Analysis

As the atrial fibrillation (AF) recurrence rate remains high after pulmonary vein isolation (PVI), additional left atrial posterior wall isolation (PWI) has been studied in randomized controlled trials, however, the results are conflicting. We performed an updated meta-analysis by searching online databases for the randomized controlled trials comparing the PWI+PVI group to the PVI alone group in patients with AF. The outcomes of interest were AF recurrence, all atrial arrhythmia recurrence, and atrial flutter/atrial tachycardia (AT) recurrence. Risk ratio (RR) with a 95% confidence interval (CI) was estimated using a random effects model. A total of 1,612 patients, with 807 in the PWI+PVI group and 805 in the PVI alone group were included. The mean age was 60 (9) years, 75% were men and 71% had persistent AF. The PWI+PVI group had lower AF recurrence as compared with the PVI alone group (25% vs 32%, RR 0.73, 95% CI 0.56 to 0.96, p=0.02). There were no significant differences in all atrial arrhythmia recurrence (RR 0.90, 95% CI 0.78 to 1.04, p=0.16), atrial flutter/AT recurrence (RR 1.19, 95% CI 0.92 to 1.55, p=0.19) or adverse event rates in the 2 groups (36 vs 31; RR 1.09, 95% CI 0.67 to 1.77, p=0.73). In conclusion, adjunctive PWI in addition to PVI can be achieved with lower AF recurrence but with a nonsignificant increase in atrial flutter/AT recurrence, resulting in an overall similar rate of all atrial arrhythmia recurrence without increasing the risk of adverse events, when compared with PVI alone strategy.

Association between residual unipolar voltage and arrhythmia recurrence after left atrial posterior wall isolation for persistent atrial fibrillation.

Posterior wall isolation (PWI) combined with pulmonary vein isolation (PVI) has proven effective for persistent atrial fibrillation (AF). However, when performing PWI, creating transmural lesions with subendocardial ablation is sometimes difficult. Endocardial unipolar voltage amplitude had a higher sensitivity than bipolar voltage mapping for identifying intramural viable myocardium in the atria. In this study, we aimed to retrospectively investigate the correlation between the residual potential in the posterior wall (PW) following PWI for persistent AF and atrial arrhythmia recurrence using endocardial unipolar voltage. This was a single-center observational study. Patients who underwent PVI and PWI for persistent AF in the first procedure between March 2018 and December 2021 at the Tokyo Metropolitan Hiroo Hospital were included in this study. The patients were divided into two groups based on the presence of residual unipolar PW potentials after PWI with a cutoff of 1.08 mV and the recurrence of atrial arrhythmias was compared. In total, 109 patients were included in the analysis. Forty-three patients had residual unipolar potentials after PWI and 66 patients had no residual unipolar potentials. The atrial arrhythmia recurrence rate was significantly higher in the group with residual unipolar potential (41.8% vs. 17.9%, p = 0.003). The residual unipolar potential was an independent predictor of recurrence (odds ratio: 4.53; confidence interval: 1.67-12.3, p = 0.003). Residual unipolar potential after PWI for persistent AF is associated with recurrent atrial arrhythmias.

Outcomes of adjunct posterior wall isolation in atrial fibrillation patients with cardiac implantable electronic devices.

Although pulmonary vein isolation (PVI) remains the cornerstone of catheter ablation of atrial fibrillation (AF), several studies have illustrated clinical benefits associated with PVI with posterior wall isolation (PWI). This retrospective study investigated the outcomes of PVI alone versus PVI+PWI performed using the cryoballoon in patients with cardiac implantable electronic devices (CIEDs) and paroxysmal AF (PAF) or persistent AF (PersAF). Acute PVI was achieved in all patients using cryoballoon ablation. Compared to PVI alone, PVI+PWI was associated with longer cryoablation, fluoroscopy, and total procedure times. Adjunct radiofrequency was required to complete PWI in 29/77 patients (37.7%). Adverse events were similar with PVI alone versus PVI+PWI. But at 24±7 months of follow-up, not only cryoballoon PVI+PWI was associated with improved freedom from recurrent AF (74.3%vs. 46.0%, P=.007) and all atrial tachyarrhythmias (71.4%vs. 38.1%, P=.001) in patients with PersAF, cryoballoon PVI+PWI also yielded greater freedom from AF (88.1%vs. 63.7%, P=.003) and all atrial tachyarrhythmias (83.3%vs. 60.8%, P=.008) in those with PAF. Additionally, PVI+PWI was associated with higher reductions in atrial tachyarrhythmia burden (97.9%vs. 91.6%, P<.001), need for cardioversion (5.2%vs. 23.6%, P<.001) and repeat catheter ablation (10.4%vs. 26.1%, P=.005), and a longer time-to-arrhythmia recurrence (16±6 months vs. 8±5 months, P<.001) in both PersAF and PAF patients. In CIED patients with PersAF or PAF, cryoballoon PVI+PWI is associated with a greater freedom from recurrent AF and atrial tachyarrhythmias, as compared to PVI alone during long-term follow-up.

Ablative Management of Persistent Atrial Fibrillation (PeAF) with Posterior Wall Isolation (PWI): Where Do We Stand?

Atrial fibrillation is a diverse clinical entity, with persistent atrial fibrillation (PeAF) being particularly challenging to manage. Through this paper, we discuss notable developments in our understanding of ablative strategies for managing PeAF, with a special focus on posterior wall isolation (PWI).

Wide antral circumferential vs. ostial pulmonary vein isolation using pulsed field ablation-the butterfly effect.

Wide antral circumferential ablation (WACA) in comparison to ostial pulmonary vein (PV) isolation (PVI) has been attributed with improved rhythm outcome. We investigated the feasibility, lesion formation, and rhythm outcome of WACA-PVI in comparison to ostial-PVI using pulsed field ablation (PFA). Symptomatic atrial fibrillation (AF) patients (69 years, 67% male; 67% paroxysmal AF) were prospectively enrolled into our single-center registry and underwent first-time ostial-PFA or WACA-PFA, N = 15 each. In all patients, eight pulse trains (2 kV/2.5 s, bipolar, biphasic, 4× basket/flower configuration each) were delivered to each PV. In WACA-PFA, two extra pulse trains in a flower configuration were added to the anterior and posterior antrum of the PVs. For comparison of PFA lesion size, pre- and post-ablation left atrial (LA) voltage maps were acquired using a multipolar spiral catheter together with a three-dimensional electroanatomic mapping system. WACA-PFA resulted in a significant larger lesion formation than ostial-PFA (45.5 vs. 35.1 cm2, p = 0.001) with bilateral overlapping butterfly shape-like lesions and concomitant posterior LA wall isolation in 73% of patients. This was not associated with increased procedure time, sedation dosage, or exposure to radiation. One-year freedom from AF recurrence was numerically higher after WACA-PFA than ostial-PFA (94% vs. 87%) but not statistically significant (p = 0.68). No organized atrial tachycardias (ATs) were observed. Ostial-PFA patients more often underwent re-ablation due to recurrent AF episodes. WACA-PFA is feasible and resulted in significantly wider lesion sets than ostial-PFA. Concomitant posterior LA wall isolation occurred as an epiphenomenon in the majority of patients. The WACA approach was associated with neither increased procedure and fluoroscopy times nor statistically significant differences in 1-year rhythm outcome. ATs were absent.

Efficacy and durability of posterior wall isolation with ethanol infusion into the vein of Marshall.

Ethanol infusion into the vein of Marshall (EIVOM) is expected to be an adjunctive therapy for mitral isthmus (MI) ablation. Additionally, EIVOM can widely ablate the epicardium via the branches that extend to the left atrialposterior wall (LAPW) and facilitate LAPW isolation. This study aimed to investigate the efficacy and durability of LAPW isolation with EIVOM. Our cohort consisted of 413 patients with atrial fibrillation (AF)who underwent both LAPW and MI ablations. EIVOM was first attempted in 177 (35%) patients with adequate VOMs. The VOM was infused with 5 mL of ethanol with a double coaxial guiding catheter technique. Both ablations were performed only by radiofrequency ablation (the RF group) in the remaining 236 (57%) patients. EIVOM with 5 mL of ethanol was completely achieved in 106 patients (the EIVOM group). The application duration of LAPW isolation did not differ significantly between the two groups (718 ± 276 vs. 709 ± 288 s; p = .78). LAPW debulking ablation was required in 64/106 (60%) and 176/236 (75%) patients in the EIVOM and RF groups, respectively (p < .05). However, AF- or atrial tachycardia-free survival analyses revealed no significant differences between the two groups (log-rank p = .70). Among the cases of recurrence, 17 and 38 patients underwent subsequent ablation sessions; LAPW was reconnected in 9/17 (53%) and 25/38 (53%) patients (p = .36)in the EIVOM and RF groups, respectively. EIVOM reduced the number of cases that required LAPW debulking ablation but did not improve the durability of LAPW isolation or clinical outcomes.

Lesion formation following pulsed field ablation for pulmonary vein and posterior wall isolation.

Pulsed field ablation (PFA) results in unique lesion formation, but there is lack of in-vivo validation in terms of scar formation following atrial fibrillation (AF) ablation. We aimed to access atrial lesion formation based on late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (CMR) following PFA for pulmonary vein (PV) and posterior wall isolation (PWI). AF ablation was performed in 10 patients using a 31mm pentaspline PFA catheter. After pulmonary vein isolation (PVI; n=8 PFA-applications/ PV; n=4 in basket and n=4 in flower configuration), another eight applications in flower configuration were conducted for concomitant PWI. Patients underwent LGE CMR 3 months after ablation aiming for quantification of left atrial (LA) scar. Acute procedural success was achieved in all patients. Mean procedure duration was 62±7min. and mean LA dwell time of the PFA catheter was 13±2min. Mean post ablation total LA scar burden was 8.1±2.1% and mean scar width was 12.8±2.1mm. At the posterior LA, 22.6±2.2% of the anatomical segment resulted in chronic scar tissue, concentrated at the PW. Postablation CMR found no evidence for PV stenosis or collateral damage of adjacent structures. At 7 months of follow-up, 9/10 patients (90%) were free from arrhythmia recurrence. PFA for AF resulted in durable and transmural atrial scar tissue at the PVs and PW. LGE CMR found a very homogeneous and contiguous lesion pattern with no signs for collateral damage.

Pulmonary vein and posterior wall isolation and mitral isthmus block with radiofrequency vs electroporation: comparing a classic to a novel technique for the ablation of persistent atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Persistent atrial fibrillation (PerAF) ablation continues to be a challenge due to the wide variety of approaches and a high arrhythmia recurrence. In our center, the usual strategy for PerAF ablation comprises posterior wall isolation (PWI) and mitral isthmus block (MIB) in addition to pulmonary veins isolation (PVI), with alcoholization of the Vein of Marshall (VoM) if possible. Pulsed-field ablation (PFA) has emerged as a novel and promising source of energy for AF ablation, having proved its feasibility and safety for PVI. However, there is no evidence in terms of feasibility and safety about a combined strategy of PVI, PWI and MIB. Purpose Our aim was to assess the feasibility and safety of PVI, PWI and MIB with PFA for PerAF ablation, and compare it to the same approach carried out with radiofrequency (RF) +/- alcoholization of the VoM, in terms of procedural parameters, acute success and complications rate. Methods All patients who undergone PerAF ablation with PFA and RF between November 2021 and September 2022 were consecutively and retrospectively included in the study. Demographic data, procedural data, rate of acute access (in achieving isolation or block of the targeted substrates) and complications rate were collected. Results Ninety patients with PerAF ablation were included (45 with the classic approach [RF ± VoM] and 45 with PFA). No differences were found in mean age and gender (67.0±9.1 vs 67.0±10.02 y.o, p=0.96 and 26.6% vs 24.4% of women, p=0.8). No differences were found with regard to previous cardiopathy or other comorbidities. There were also no differences in left atrial volume (157±41.1vs145±54.8ml, p=0.26). As for the procedure, the PFA group had shorter procedural time (119.8±26.3vs 84.1±20.0 min, p=0.00) but longer fluoroscopy time (17.8±6.9vs23.6±6.7 min, p=0.0002) and higher fluoroscopy dose (36.1±25.3vs67.3±84.7 Gy.cm2, p=0.02). No differences were found in the acute success rate to achieve PVI (100% in all), PW isolation (97.7%vs100%, p=0.31) or mitral isthmus block (97.7%vs100%, p=0.31) between RF±VoM and PFA groups, respectively. Of note, among the patients in AF rhythm at the procedure, the rate of reversion to sinus rhythm during ablation was much higher in the PFA group (7.14% vs 77.7%, p=0.00), with a lower rate of cardioversion (92.8% vs 22.2%, p=0.00) during the procedure. No significant differences were found with regard to the number of complications (13.3% [6 cases] in the RF±VoM group vs 6.6% [3 cases] in the PFA group, p=0.27). Conclusions PFA shows a good feasibility and safety profile for PVI, PWI and MIB with shorter procedural time and higher rate of conversion to sinus rhythm during ablation compared to the classic strategy with radiofrequency.

Initial experience and early outcomes of posterior wall ablation using pulsed-field ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background The success rate of pulmonary vein isolation (PVI) is lower in patients with persistent compared to paroxysmal atrial fibrillation (AF). In patients with persistent AF, additional isolation of the posterior wall is under investigation to improve ablation success. Pulsed field ablation (PFA) might be superior to conventional methods for posterior wall isolation due to its safety profile and might allow for posterior wall ablation (PWA) rather than posterior wall isolation (PWI) based on its efficiency. Purpose To report our initial experience with PWA using a multipolar PFA catheter. Methods Consecutive patients with PWA during their first PFA procedure for AF between May 2021 and October 2022 at our institution were included. For PWA, the multipolar PFA ablation catheter was used in flower configuration only. With the wire in each of the pulmonary veins and the sheath angulated posteriorly, we first performed 2 x 2 sets of anchor lesions with the catheter rotated by ~30° between sets. Next, with the wire retracted back into the device, single sets of two applications were delivered in an overlapping fashion and without catheter rotation between lesion sets to cover the entire posterior wall between the superior and inferior pulmonary veins. Finally, completeness of PWA was verified by 3D electro-anatomical mapping. Results PWA using PFA was performed in 163 patients (mean age 67 years, 71% male). In 55 patients (34%), PWA was added to PVI during the first AF ablation procedure and the remaining 108 patients (66%) had undergone a median of two (interquartile range 1-3) previous AF ablation procedures using either cryoablation and/or radiofrequency ablation. Of all patients, 45 (28%) had paroxysmal, 93 (57%) persistent AF, and 22 patients (15%) left atrial reentry tachycardia. Median procedure duration and fluoroscopy time were 120 (70-190) min, and 18 (9-36) min, respectively. 3D-EAM showed no residual electrical signal (&amp;gt;0.05 mV) on the posterior wall at the end of the procedure in any patient. No cardiac tamponade, stroke, phrenic nerve injuries, atrio-esophageal fistula, or clinically manifest coronary spasm occurred. A repeat ablation was performed in seven patients (4%) and 3D-EAM showed persisting posterior wall isolation in six (86%) and recurrent roof dependent atrial flutter in one patient. Despite PWA, low-voltage signals were found in four (67%) cases on the superior aspect of the posterior wall. Conclusions Left atrial PWA can be performed safely and efficiently using PFA. Early data on the durability of PWA are promising. The impact of PWA on arrhythmia-free outcome needs to be evaluated in larger, prospective randomized trials.

The impact of posterior wall ablation in conjunction with pulmonary vein isolation in patients with persistent atrial fibrillation: a meta-analysis comparing cryoballoon vs. radiofrequency energy

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein isolation (PVI) remains the cornerstone of atrial fibrillation (AF) ablation. In patients with persistent AF (PeAF), additional posterior wall ablation (PWA) has been proposed to improve outcomes. Individual small series have included patients ablated with a cryoballoon (CB) and radiofrequency (RF) energy and have yielded controversial results. We conducted a meta-analysis of available data to assess the incremental impact of PWA based on type of energy used for ablation. Objective To evaluate whether PVI + PWA is a more effective approach for treatment of PeAF than PVI alone based on ablation energy used. Methods The online databases (Pubmed, Medline, Embase) were searched using the terms "pulmonary vein isolation", "posterior wall isolation", or "posterior wall ablation". Out of 1917 studies, eight met our strict criteria (Table). Specifically, patients were undergoing de novo ablation for treatment of PeAF using either CB or RF. Patients had PVI alone vs PVI + PWA; studies that delivered additional ablations (except for cavotricuspid isthmus) were excluded. The primary outcome was recurrence of any atrial tachyarrhythmia (AT). Results The cohort consisted of 1607 patients (66 ± 17 years, 75% male); 830 (52%) patients were ablated CB and 777 (48%) patients were ablated with RF (Table). In the CB group, AT recurrence was significantly higher in patients who underwent PVI alone as compared to those who also had additional PWA (OR 2.55, 95% CI [1.89, 3.42], P &amp;lt; 0.0001, Figure). In contrast, in the RF group, outcome between the 2 groups (OR 1.40, 95% CI [0.81, 2.42], P = 0.22, Figure) was similar. Conclusions Addition of CB based PWA to PVI in patients with PeAF undergoing ablation was associated with improved long-term ablation success. However, RF based PVA did not appear to confer the same benefit. Additional randomized studies are needed to determine the impact of ablation energy in patients undergoing PWA during ablation of PeAF.

The novel left atrial anterior 'seatbelt' line reduces sustained atrial arrhythmia by 72% compared to pulmonary vein isolation alone in a cohort of 400 virtual atria models

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No.860974. Background The success-rate of pulmonary vein isolation (PVI) is modest in persistent atrial fibrillation (AF), but additional empirical ablation, such as posterior wall isolation (PWI), has not been shown to reduce the rate of AF recurrence. The "seatbelt", an anterior linear ablation lesion connecting the right superior pulmonary vein to the mitral annulus, is a novel substrate modification approach that is yet to be tested in a large-scale randomised clinical trial. Purpose To use in-silico trials with human-based modelling and simulation to compare the efficacy of (i) PVI alone, (ii) PVI and PWI (PVI+PWI), or (iii) PVI and seatbelt (PVI+SB) for the prevention of atrial arrhythmia in large populations of virtual patient models. Methods AF was simulated in a cohort of 400 virtual atrial models with anatomical and electrophysiological variability, with AF persisting for &amp;gt;7 seconds defined as sustained. Models which sustained AF were each independently subjected to all three ablation approaches before repeating the AF induction protocol. Results Three hundred forty-four (86%) atrial models developed sustained AF at baseline. After applying the ablation lesions, substantially fewer models sustained atrial arrhythmias in the PVI+SB group (50 [14%] vs. 134 [39%] with PVI+PWI vs. 172 [50%] with PVI). PVI+SB was more effective than PVI and PVI+PWI in preventing both AF and atrial flutter (i.e., presence of a single rotor), since PVI and PVI+PWI led to the formation of anatomical re-entries around the rings of the pulmonary veins and the posterior wall of the left atrium, respectively (Figure). Therefore, PVI+SB restricted atrial flutter mainly to the right atrium (either anatomical, around the inferior cava vein, or functional, meandering throughout the venous portion of the right atrium, Figure). Importantly, in all three ablation strategies, the likelihood of AF recurrence was directly proportional to the surface area of the right atrium (AF probability increased 0.95%/cm², 0.88%/cm² and 0.56%/cm² after PVI+SB, PVI+PWI and PVI, respectively). The role of the right atrial size was less accentuated for PVI alone, since after the ablation the entire left atrial body was still available for rotor anchoring. Moreover, an enlarged left atrium enabled the appearance of micro-re-entries in the anterior and inferior wall of the left atrium, even after applying floor and roof lines. One atrial model additionally presented a rotor in the posterior wall of the left atrium after completely isolating it from the left atrial body. Conclusion(s) In a cohort of 400 virtual atrial models, PVI+SB reduced sustained atrial arrhythmias by 72% compared to PVI alone and by 64% to PVI+PWI, but AF could still originate in an enlarged right atrium.

Hybrid ablation of atrial fibrillation: long-term outcomes from a single center prospective experience

Abstract Funding Acknowledgements Type of funding sources: None. Background/introduction Hybrid ablation of atrial fibrillation (AF) is emerging as a new technique for rhythm control with good clinical outcomes, especially in patients with non-paroxysmal AF. However, the role of hybrid AF in redo procedures is not clear. Moreover, long term clinical outcomes studies are lacking. Purpose The aim of this study is to define the long-term clinical outcomes of hybrid AF ablation in a large cohort from a single high-volume center. Furthermore, a correlation between the timing of hybrid AF and the outcomes is aimed. Methods All consecutive patients undergoing to hybrid AF ablation between 2014 and 2020 were enrolled in a prospective fashion. Hybrid ablation was performed in a one-step procedure consisting of: 1) Bilateral thoracoscopic epicardial ablation and 2) Percutaneous mapping and ablation. Pulmonary veins and posterior wall isolation was performed in all patients. Additional lesion set was performed based on physician judgement and clinical indication, including the following: superior vena cava isolation, bicaval line, anterior or posterior mitral line, cavotricuspid isthmus. Hybrid ablation time was analyzed as first hybrid procedure or redo hybrid after previous failed percutaneous procedure. The primary endpoint was defined as freedom from any atrial tachyarrhythmias (ATas) ≥ 30 seconds after a 90-day post-ablation blanking period. Results A total of 120 patients were included, 92 (76.7%) patients with persistent or long-term persistent AF and 28 patients (23.3%) with paroxysmal AF. Hybrid ablation was the first procedure in 85 (70.8%) patients and the second or third procedure (redo or re-redo) in 35 (29.2%) patients. Compared to patients with a second or third hybrid procedure, patients with a first hybrid procedure had more often persistent AF [81 patients (95.3%) vs 11 patients (31.4%), p&amp;lt;0.001]. At a mean follow-up of 52.1 months ± 29.0 there were 36 (30%) ATas recurrences, Figure 1. There was no significant difference in ATas free survival between patients with a first hybrid procedure and patients with a second or third hybrid procedure (69.4% vs 71.4%, Log-Rank p=0.81), Figure 2. Patients with a second hybrid procedure had higher ATas free survival compared to patients with a third hybrid procedure (86.4% vs 46.2%, Log-Rank p=0.01) Conclusion In a large cohort undergoing to hybrid AF ablation, the recurrence rate was 30% at a long-term follow-up of more than 4 years. Timing is of utmost clinical importance as delaying hybrid approach might be associated with worse clinical outcome.

Impact of vein of Marshall ethanol infusion on left atrial function: an MRI study

Abstract Funding Acknowledgements Type of funding sources: None. Background Previous data suggested that left atrial (LA) function may be impaired by extensive atrial fibrillation (AF) ablation. Ethanol infusion of Vein of Marshall (EI-VOM) as an adjunctive therapy to pulmonary vein isolation is an emerging therapeutic strategy that has shown to improve efficacy in persistent AF ablation procedures and mitral isthmus line. The impact of EI-VOM scar formation on LA function has not been addressed. Purpose To analyse the effect of EI-VOM on LA function, evaluated by magnetic resonance imaging (MRI) strain parameters. Methods Twelve patients referred for de novo persistent AF or any repeat procedure were included. MRI was performed previous (baseline) and 3-month after AF ablation. MRI images were analyzed off-line with specialized post-processing software. LA volumes, LA strain parameters, including LA global longitudinal strain (GLS), LA reservoir (LASr), conduit (LAScd) and contractile (LASct) strain; LA ejection fraction (LAEF), LA passive emptying function (LAPEF) and LA active emptying function (LAAEF) were measured from SSFPs two-chamber cine sequences. Results Two patients were excluded due to absence of VOM and failed ethanolization. Ten patients (83%) underwent both MRI studies (64 [55-71]years; 80% men; de novo ablation of persistent AF (50%)). Six patients received additional mitral isthmus line and three posterior wall isolation. Mean baseline indexed LA volume was 62.7ml/m2 [47-73]. Baseline LA strain and EF parameters were: LA GLS 17.16±15.3, LASr 17.80±14.9%, LAScd -5.96±3.7%, LASct -10.35±9.5%; LAPEF 5.89±9.8, LAAEF 23.87±17.0 and LAEF 27.6±18.3%. At 3-months follow-up, no AF recurrences were detected. No differences were found regarding LA volume (57.6ml/m2 [42-64], p=0.671), strain parameters (LA GLS Δ0.62, p=0.903; LASr Δ0.02, p=0.991; LAScd Δ-0.84, p=0.563; LASct Δ0.54, p= 0.874) and LAEF parameters (LAPEF Δ4.82, p=0.592; LAAEF Δ3.03, p=0.903; and LAEF Δ7.0, p=0.213). Conclusions EI-VOM appears as a safe adjunctive strategy in AF ablation in terms of LA function. The present study did not show impairment in the main MRI strain parameters.

Insights into level of pulmonary vein isolation using pulsed-field ablation for atrial fibrillation and unexpected effects in the posterior wall

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Pulse field ablation (PFA) has emerged as an effective, safe and efficient tool for pulmonary vein isolation (PVI). Purpose We studied the extent of PVI, specifically the isolation of PV antrum, carina and left atria’s posterior wall after PFA with an ultrahigh density mapping (UHD). Methods We involved the first patients referred for atrial fibrillation (AF) ablation treated with a PFA multispline catheter. PFA-lesion extension was assessed with a voltage-map UHD mapping performed before and immediately after PVI. Results Sixty-one consecutive patients underwent PVI with PFA (62±10 year old, 23 women, 39 paroxysmal AF). Four out of 61 patients were excluded because their posterior wall was isolated with extra aplications on purpose. Acute results involved a 100% success of PVI and the only safety issue was a pericardial effusion in one patient managed conservatively. Mean procedure and fluoroscopy times were 59±39 min and 16±5 min, respectively. UHD immediately after PVI revealed early reconnection just in one vein (1/228 veins). PFA created wide antral circumferential lesions without electrical activity registered by UHD mapping inside the isolation area. There were no notch-like normal voltage areas at the anterior or posterior side of carinas. As a result of the PVI with this technology, it was observed the existence of a narrow corridor in the posterior wall in 8 patients (14%) and in another 8 cases right and left antral ablation converged at the posterior wall creating an unexpected isolation area. There was a significant relationship between LA posterior inter-carina distance and posterior wall´s level of isolation (77,1±7mm, no affectation; 68,8±7mm narrow corridor; 60,3±1mm posterior wall isolation (fig 1); p=0.036). Finally, it was a significant linear correlation between posterior inter-carina distance and the distance between the ipsilateral, antral levels of isolation at the posterior wall (fig 2, r=0.79, p=0.001) Conclusion(s) PFA creates wide antral circumferential PVI lesions involving the ipsilateral veins carina. Nevertheless, in small left atria it can create an undesired isolation or a narrow corridor in the posterior wall.

Comparison of zero fluoroscopy versus fluoroscopy guided ablation for atrial fibrillation: A single center experience

Abstract Funding Acknowledgements Type of funding sources: None. Background With advances in mapping equipment and increased use of intracardiac echocardiography (ICE), atrial fibrillation (AF) ablations can be safely performed without fluoroscopy. Benefits include no radiation exposure to patient and staff and reduced long-term orthopedic complications related to use of lead aprons for staff. Published data comparing zero fluoroscopy ablation (ZFA) and conventional fluoroscopy guided ablation (CFA) for AF is limited to small case series and meta-analysis. Aim To evaluate the safety and procedural outcomes of a simplified ZFA approach, comparing it to standard of care (CFA). Methods Consecutive AF cases from 03/2021 to 09/2022 at our institution were included. 120 cases underwent ZFA (RF ablation, ICE and 3D mapping guided) and 155 cases underwent CFA (Cryo or RF ablation, fluoroscopy, ICE and 3D map guided). For the ZFA group, a simplified ICE based map of relevant anatomical structures was created, in order to guide trans-septal (TS) access and left -sided ablation (See figure) and no pre-procedural imaging was obtained. All CFA cases had pre-procedural cardiac CT or MRI to evaluate left atrial anatomy. Redo ablation cases represented 17% of the ZFA and 23% of the CFA patients. All cases were performed by operators with &amp;gt;12 years of experience, and all cases underwent general anesthesia. Only two ZFA cases required a brief period of fluoroscopy (under 2 min each) to achieve safe trans-septal access (including one case with a prior ASD closure device). Results Mean age was 67 for ZFA and 69 for CFA groups respectively (p=NS). 69% of ZFA and 71% of CFA cases were men. Persistent AF cases more frequently underwent posterior wall isolation in the ZFA group (98% vs 68%, P&amp;lt;0.01), but despite this, procedural times were similar for both groups (168±55 min ZFA vs 172±51 min CFA, P=NS). Procedural success (pulmonary vein isolation ± posterior wall isolation) was achieved in all ZFA and 99% of CFA cases. At a mean follow up 12 months, Freedom for AF was 81% for paroxysmal AF and 74% for persistent AF cases in the ZFA group, and 79% for paroxysmal AF cases and 71% for persistent AF cases in the CFA group (p=NS). Procedural complications included one TIA in the ZFA group and 2 pericardial effusions in the CFA group (p=NS). Use of antiarrhythmic drugs post ablation did not differ between the ZFA and the CFA groups (23% vs 27%, p=NS). Conclusion Our ZFA approach for AF was safe, effective and produced similar outcomes compared to a traditional CFA approach. ZFA has considerable health benefits for personnel and patients without compromising procedural outcomes. The cost of ICE catheters may be offset by eliminating the need for pre-procedural imaging (CT or MRI) commonly used prior to AF ablations. Our study adds to the growing literature supporting the safety of catheter ablation in a non-fluoroscopy environment.

Pathophysiology of recurrent atrial fibrillation after initial cryoballoon ablation and clinical outcome of the second ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background There are limited clinical studies on recurrent atrial fibrillation (AF) mechanisms after initial cryoballoon ablation (CBA). Purpose We aimed to elucidate the mechanisms of AF recurrence after CBA based on electrophysiological findings obtained during the second ablation and the response to treatment. Methods Of 885 patients who underwent CBA at our hospital between 2016 and 2022, 50 (5.7%) patients (age 68 ± 9.2 years, 62% male, 52 % paroxysmal AF, body mass index (BMI) 25 ± 3.8 kg/m2, left atrial diameter (LAD) 44 ± 5.9mm, left ventricular ejection fraction (LVEF) 66 ± 11%, CHADS2 score 1.9 ± 1.4) were included. All the patients were treated with an Arctic Front Advance™ in the initial CBA. Each pulmonary vein (PV) was treated with a target time of 180 sec. Routine left atrial roof line and posterior wall isolation was not created. However, tricuspid valve isthmus isolation (CTI) and superior vena cava (SVC) isolation were added as required. The findings obtained with the 3D-mapping system during the second ablation were analyzed. Furthermore, the contents of the second ablation and the clinical outcomes were investigated. Results The first ablation successfully isolated PVs in all patients, and additional radiofrequency ablations were CTI ablation in 28 patients and superior vena cava (SVC) isolation in 6 patients. The second ablation was done after 24±16 months. At recurrence, persistent AF was 24%. Furthermore, atrial flutter was recorded in 16% of the 50 cases. The 3D-mapping systems used for guidance were RHYTHMIA HDx™ in 42 cases, CART-XP™ in 5 cases and EnSite NavX™ in 3 cases. Electrical reconnection of PV was detected in 14 patients. They included seven left-superior PVs, two left-inferior PVs, two left-common PVs, four right-superior PVs and five right-inferior PVs. There were 11 cases of conduction only in the carina area, five with left-sided and six with right-sided. All second ablations were treated with high-frequency irrigation catheters. The treatments were PV re-isolation in 14 patients, isolation area expanding in 43 patients, SVC isolation in 24 patients, CTI ablation in 3 patients, and mitral isthmus ablation in 2 patients. After 24.8 ± 14.9 months, treatment outcomes were as follows; AF was completely cured in 23 patients, anti-arrhythmic drugs were required in 23 patients, and no effects in 4 patients. Comparing the completely cured patients’ group (23 patients) with the other (27 patients), age (65.1 ± 9.3 years vs 70.5 ± 8.6 years, p &amp;lt; 0.05) and CHADS2 score (1.5 ± 1.3 vs 2.3 ± 1.3, p &amp;lt; 0.05) have significant differences. There were no differences in the presence of PV reconnection, BMI, LAD, LVEF and second ablation contents. Conclusion In patients with recurrent AF after CBA, less than 30% had PV-reconnection, and its disappearance was not associated with AF disappearance. Non-PV foci, except SVC origin, might cause recurrent AF after CBA.

Hybrid atrial fibrillation ablation: long-term outcomes from a single-centre 10-year experience.

Hybrid atrial fibrillation (AF) ablation is a promising approach in non-paroxysmal AF. The aim of this study is to assess the long-term outcomes of hybrid ablation in a large cohort of patients after both an initial and as a redo procedure. All consecutive patients undergoing hybrid AF ablation at UZ Brussel from 2010 to 2020 were retrospectively evaluated. Hybrid AF ablation was performed in a one-step procedure: (i) thoracoscopic ablation followed by (ii) endocardial mapping and eventual ablation. All patients received PVI and posterior wall isolation. Additional lesions were performed based on clinical indication and physician judgement. Primary endpoint was freedom from atrial tachyarrhythmias (ATas). A total of 120 consecutive patients were included, 85 patients (70.8%) underwent hybrid AF ablation as first procedure (non-paroxysmal AF 100%), 20 patients (16.7%) as second procedure (non-paroxysmal AF 30%), and 15 patients (12.5%) as third procedure (non-paroxysmal AF 33.3%). After a mean follow-up of 62.3 months ± 20.3, a total of 63 patients (52.5%) experienced ATas recurrence. Complications occurred in 12.5% of patients. There was no difference in ATas between patients undergoing hybrid as first vs. redo procedure (P = 0.53). Left atrial volume index and recurrence during blanking period were independent predictors of ATas recurrence. In a large cohort of patients undergoing hybrid AF ablation, the survival from ATas recurrence was 47.5% at ≈5 years follow-up. There was no difference in clinical outcomes between patients undergoing hybrid AF ablation as first procedure or as a redo.