Floor Line Research Articles

Clinical findings from a large endo-epicardial atrial arrhythmia ablation registry

Abstract Background Despite advances, catheter ablation success rates for persistent AF remain at 50-60%. The approach for recurrent persistent AF, beyond pulmonary vein isolation, remains contentious. Surgical maze procedures have demonstrated superior outcomes compared to catheter ablation. Catheter-based linear lesions sets have failed to demonstrate efficacy, perhaps due to a lack of consistent transmurality with endocardial radiofrequency. Objective We report our safety and clinical data of an endo-epicardial approach using high-power radiofrequency ablation for atrial arrhythmias. Methods 126 patients (80% male; mean age 65 years [43-81]) underwent redo ablation, between August 2020 and February 2024, for recurrent symptomatic atrial arrhythmias using an endo-epicardial approach. We used a standardised linear lesion set (posterior wall isolation and anterior mitral line) for recurrent persistent AF. Results Utilising an intentional coronary sinus exit and C02 insufflation technique, we achieved epicardial access in 121 anti-coagulated patients. 5 patients were found to have pericardial adhesions, prohibiting access. There were 2 LIMA punctures which were coiled, 2 cases of excess pericardial bleeding (not access related), that settled conservatively, and no surgery or death. 92% of patients received epicardial ablation. 86 anterior mitral lines (95% acute block, 79% with epi ablation), 88 roof lines (92% blocked, 50% with epi ablation) and 81 floor lines (98% blocked, 36% with epi ablation) were undertaken. 106 posterior wall isolations were performed (94% isolated, 51% epi ablation). 75 patients had a standardised lesion set and were included for recurrence analysis. 49 had persistent AF (71% male, mean age 65 years, mean LAVI 38 ml/m2, 26 PVI at baseline and 23 PV reconnections) and 26 longstanding persistent AF (92% male, median age 64 years, mean LAVI 37.1 mls/m2, 16 PVI at baseline and 10 PV reconnections). 82% with persistent AF (median follow up time 11 months) and 38% with longstanding persistent AF (median follow up time 10.1 months) maintained sinus rhythm. The submitted image demonstrates the freedom from persistent AF, for the cohort who are beyond the 3-month blanking period, as per classification of atrial arrhythmia. Conclusion In one the largest cohorts to date, we have shown that endo-epicardial atrial ablation is feasible and safe with epicardial ablation allowing improved transmurality and thus acute linear block. Clinical outcomes, using a posterior wall isolation and anterior mitral line, were favourable for persistent but not longstanding persistent AF.

Efficacy of the peak frequency map for left atrial posterior wall isolation.

Complete isolation of the left atrial posterior wall (LAPW) is challenging owing to overlapping epicardial conduction. Peak frequency (PF) is a novel parameter that focuses on near- and far-field electrogram components. In this study, we aimed to determine whether transmural block completion is related to the ablation site PF. We analyzed 44 consecutive patients undergoing initial LAPW isolation (LAPWI) between June 2023 and February 2024. Pre-LAPWI and PF maps were obtained using an HD-Grid catheter. In 17 of the 44 patients (Group-1), LAPWI was performed conventionally. In the remaining 27 patients (Group-2), PF-guided LAPWI was applied based on Group-1 results. In Group-1, the left atrial (LA) roof and floor line success rates were 58.8% and 76.5%, respectively. The average PF value in the roof lines of patients with a completed block line was significantly higher than that of the remaining patients (286.6 ± 29.3 Hz vs. 236.1 ± 40.9 Hz, p = .012), but the floor lines were similar. In Group-2, relatively high PF values were targeted to achieve complete block of the LA roof and floor lines, following the results obtained in Group-1. The LA roof line success rates (92.6% vs. 58.8%, p = .007), total number of radiofrequency (RF) applications (22.7 ± 5.6 vs. 27.6 ± 8.5, p = .03), and procedural time (32.6 ± 18.3 vs. 47.9 ± 25.6 min, p = .03) differed between Group-1 and Group-2. Using a PF map for determining the optimal ablation line for LAPWI by RF catheter ablation is feasible.

Risk assessment of esophageal ulceration following left atrial radiofrequency linear ablation.

Esophageal safety following radiofrequency (RF) left atrial (LA) linear ablation has not been established. To determine the esophageal safety profile of LA linear RF lesions, we performed systematic esophagogastroduodenoscopy in all patients with intraesophageal temperature rise (ITR) ≥ 38.5°C. Between December 2021 and July 2023, a total of 200 consecutive patients with atrial tachyarrhythmia (ATA) underwent linear ablation with posterior dome (roof or floor) or posterior mitral isthmus line transection. Patients with ITR ≥ 38.5°C were scheduled for esophageal endoscopy ~3 weeks after ablation. Patient and ATA characteristics, procedural parameters, endoscopy findings and ablation lesion data were collected and analyzed. One hundred thirty-threeout of 200 (67%) patients showed ITR ≥ 38.5°C during LA linear ablation. ITR (with maximal temperature of 45.7°C) was more frequently observed during floor line ablation (82% of cases). ITR was less observed during roof line ablation (34%) and posterior mitral isthmus ablation (4%). Endoscopy, performed in 115 patients after 24 ± 10 days, showed esophageal ulceration in four patients (two patientsKansas City classification [KCC] 2a and two patients KCC 2b). No patient showed esophageal perforation or fistula. Temperature rise during LA linear ablation is frequent and ulceration risk exists, particularly when floor line is performed. Safety measures are needed to avoid potential severe complications like esophageal perforation and fistula.

Time-Dependent Reliability Analysis of Anhydrite Rock Tunnels under Swelling Conditions: A Study on Stress, Deformation, and Engineering Solutions

This study presents an analytical approach for evaluating the reliability of anhydrite rock tunnels, focusing on their characteristic swelling behavior. Anhydrite rocks, prone to significant expansion upon moisture exposure, pose a challenge in tunnel construction, potentially leading to structural issues such as floor heave and lining damage. To address this, this research develops an elastic swelling analytical solution based on humidity stress field theory, enabling the assessment of time-dependent stress and deformation changes in anhydrite tunnels. The solution’s applicability is demonstrated through its application to the Lirang tunnel. The investigation into the effects of support pressure, swelling time, and reserved deformation on tunnel reliability reveals that circumferential stress at the tunnel wall increases by 13.94% and 21.86% for swelling periods of 30 and 365 days, respectively. Similarly, radial displacement escalates by 22.97% and 35.93% over these periods, highlighting the significant impact of swelling behavior. Using a spreadsheet-based First Order Reliability Method (FORM) for analysis, this study finds that the original design of the Lirang tunnel did not meet the desired reliability standards under swelling conditions. However, strategic adjustments in construction variables, such as increasing support pressure to 1.2 MPa or enhancing reserved deformation to 59 mm, elevated the tunnel’s reliability to meet safety requirements. This research provides a vital framework for assessing and enhancing the reliability of anhydrite rock tunnels, considering the long-term effects of swelling. It underscores the importance of incorporating swelling behavior in the design and construction of tunnels in anhydrite rock formations, offering valuable insights for optimizing tunnel stability in such challenging geological conditions.

Left atrial posterior wall isolation during catheter ablation with the pulsed field ablation in patients with persistent atrial fibrillation

Abstract Background Few data are available on pulsed-field ablation (PFA) targeting left atrial posterior wall (LAPW) in persistent atrial fibrillation (PeAF) patients. Purpose We sought to explore the role of PFA in persistent AF patients beyond pulmonary vein isolation (PVI), extending the lesion set to obtain LAPW isolation. Methods We enrolled consecutive patients referred for persistent AF catheter ablation using the Farapulse PFA system at nine Italian centers. Complete 3D mapping was performed before and immediately after LAPW isolation to validate our workflow in all cases. To analyze lesions' formation and residual gaps, the line around each pair of PVs was divided into 7 distinct sections in accordance with the literature, while the roof line, the floor line, and the two longitudinal posterior wall lines were equally divided into three parts. The PW was overall divided into nine regions. This scheme has been illustrated in Figure 1, Panel A. Results Fifty patients meeting inclusion criteria were included. PVI was achieved in all 202 (100%) PVs (1 patient exhibited a left common trunk, 2 patients exhibited a right middle cardiac PV). One-hundred ninety-eight (98.0%) PVs were acutely isolated on first pass, as confirmed by both entrance and exit block on subsequent 3D-mapping with the mapping catheter. A total of 7 PV gaps were detected through 3D mapping: 4 at the RSPV, 2 at the RIPV and 1 at the LSPV. When considering LAPWI, overall LAPW ablated area was 20.0±6 cm2 with lesions being deployed with the PFA catheter maneuvered in the flower configuration from one LAPW area to another. First-pass roof area (sectors #1 to #3) block was achieved in 44 (88%), first-pass floor area (sectors #7 to #9) block in 43 (86%) and inner-area (sectors #3 to #6) block in 45 (90%). A total of 23 residual LAPW activity gaps were detected through validation using high-output pacing and 3D mapping. Remapping examples has been reported in Figure 1, panel B-C-D. Evaluation of individual segments of the LAPW via signals’ assessment from the PFA splines demonstrated an accuracy of 94.9% (437 out of 450 sectors), compared to the results of subsequent high-output pacing and 3D mapping. Following PFA consolidation in these areas, LAPW isolation was successfully achieved in all cases (100%) using PFA alone, with no need for radiofrequency touch-ups. No major procedure-related adverse events were reported. Conclusion A structured workflow with the novel Farapulse PFA system allowed for a reliable, safe, and fast LAPW isolation, as confirmed by ultra-high-density 3D mapping.

Implementations of Digital Transformation and Digital Twins: Exploring the Factory of the Future

In the era of rapid technological advancement and evolving industrial landscapes, embracing the concept of the factory of the future (FoF) is crucial for companies seeking to optimize efficiency, enhance productivity, and stay sustainable. This case study explores the concept of the FoF and its role in driving the energy transition and digital transformation within the automotive sector. By embracing advancements in technology and innovation, these factories aim to establish a smart, sustainable, inclusive, and resilient growth framework. The shift towards hybrid and electric vehicles necessitates significant adjustments in vehicle components and production processes. To achieve this, the adoption of lighter materials becomes imperative, and new technologies such as additive manufacturing (AM) and artificial intelligence (AI) are being adopted, facilitating enhanced efficiency and innovation within the factory environment. An important aspect of this paradigm involves the development and utilization of a modular, affordable, safe human–robot interaction and highly performant intelligent robot. The introduction of this intelligent robot aims to foster a higher degree of automation and efficiency through collaborative human–robot environments on the factory floor and production lines, specifically tailored to the automotive sector. By combining the strengths of human and robotic capabilities, the future factory aims to revolutionize manufacturing processes, ultimately driving the automotive industry towards a more sustainable and technologically advanced future. This study explores the implementation of automation and the initial strides toward transitioning from Industry 4.0 to 5.0, focusing on three recognized, large, and automotive companies operating in the north of Portugal.

Abstract 15606: Effectiveness and Safety of the Dual Epicardial & Endocardial Procedure (DEEP) Approach for Treatment of Subjects With Persistent or Long Standing Persistent Atrial Fibrillation (PersAF/LSPAF) With Radiofrequency Ablation

Background: A collaborative approach between Electrophysiologists (EP) and Cardiothoracic Surgeons (CTS) to effectively target pulmonary veins (PVs) and substrate beyond PVs may improve outcomes for persistent and longstanding persistent AF (PersAF/LSPerAF). Hypothesis: A minimally invasive hybrid approach of bilateral thoracoscopic epicardial ablation and left atrial appendage exclusion (LAAE) with endocardial mapping/ablation (Hybrid approach) is safe and effective to treat advanced AF patients who have failed medical therapy. Aim: DEEP (NCT02393885) aims to establish safety and effectiveness of a Bipolar Radiofrequency (RF) System in a Hybrid approach to treat PersAF/LSPerAF. Methods: DEEP is a prospective, international, single arm trial at 17 sites. Key eligibility: adults with drug refractory PersAF/LSPerAF, left atrial diameter (LAD) ≤5.5cm, failed class I/III AAD, and ≤2 previous failed endocardial catheter ablations (CA). Epicardial surgical ablation included PV isolation, roof and floor lines (posterior LA box), left superior PV to LAA lesion, ganglionic plexi and Ligament of Marshall ablation and LAAE. CA followed 91-121 D post epicardial procedure. After 90 D blanking and 90 D AAD optimization periods, 24-hr rhythm monitoring and ECG were performed 6 and 12 M post CA with symptom driven monitoring between. Primary effectiveness was defined as freedom from atrial arrhythmia (>30 sec) absent new/increased dose of previously failed AAD through 12 M. Safety was device/procedure-related SAEs within 30 D of epicardial ablation and 7 D of CA in all who received anesthesia. Results: Ninety patients were enrolled in 2015-2020, 83.3% PersAF, 16.7% LSPerAF, mean age 63.4±7.74 yrs, 83.3% male, mean BMI 29.9, CHAD2DS2-VASc median 2.0 (1.0, 3.0), 48% failed CA, median AF duration 3.8 yrs, mean LAD 4.5cm. Primary effectiveness 70.6% (60/85; 95% CI 60.9%, 80.3%, p=0.0232) and freedom from AF through 12 M 78.8% (p=0.0002). The adverse event rate was 6.7% (6/90); equal in epi- and endocardial cohort. Both primary endpoints met prespecified success criteria. Conclusion: A collaborative approach between EP and CTS to Hybrid ablation is effective for PersAF/LSerPAF when benefit-risk is deemed favorable, given limited alternative treatments.

Abstract 11697: Combined-Energy Pulmonary Vein Isolation and Posterior Wall Isolation for Persistent Atrial Fibrillation: Results of a 3-year Follow-Up

Introduction: Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation for paroxysmal atrial fibrillation (AF), but the optimal ablation strategy for persistent AF (PsAF) remains controversial. Hypothesis: The purpose of this study was to investigate whether combined-energy cryoballoon (CB) PVI and radiofrequency (RF) left atrial posterior wall isolation (LAPWI) at index ablation of PsAF yields higher success than PVI alone. Methods: Patients with persistent AF (n = 186) who underwent catheter ablation between 2016 and 2019 at a single large academic medical center were retrospectively reviewed. Patients with congenital heart disease or prior left atrial ablation or surgery were excluded. Combined-energy ablation (n=92) consisted of CB antral PVI followed by RF roof and floor lines to achieve LAPWI, along with isolation inside the box as needed. The control group had PVI only (n=94) with either CB (n=57) or RF (n=37). The primary endpoint was 12-, 24-, and 36-month freedom from any documented atrial tachyarrhythmia over 30 seconds after a 90-day blanking period following catheter ablation, compared by Kaplan-Meier analysis. Secondary endpoints included AF burden, procedural parameters, and complications. Results: The primary endpoint of 12-month freedom from any atrial tachyarrhythmia was higher for the combined-energy group vs the control group (79.1% vs 58.2%, p = 0.009). This improvement was sustained at 24 months (63.0% vs 45.8%) and at 36 months (60.3% vs 43.1%) and remained significant after adjustment for clinical covariates (adjusted HR 0.45, 95% confidence interval 0.22-0.95; p = 0.03). There was no significant difference in procedure time or complication rates, however fluoroscopy time was shorter with combined-energy ablation (p<.001). Conclusions: In this single center experience, combined-energy CB-PVI and RF-LAPWI was associated with reduced AF recurrence compared to PVI with a single energy source.

Pertumbuhan Beberapa Galur Ayam Lokal Fase Starter Yang Dipelihara Pada Kandang Slat Dan Litter

Animals with genetic abilities along with the environment will express different phenotypes (P = G + L + GL). The research was conducted for 1 month in the Amahusu people's livestock business, Ambon City. The livestock used were the starter phase, totaling 72 heads aged 3 weeks with an average initial weight of 80 grams. Tools used: digital scales, places to eat, drink, cages, hygrometer, thermometer. Cages used: 12 floors of slat and 12 floors of litter measuring 50 x 50 M, drinking water, litter (wood pulp), commercial feed. The research method is an experimental method using a completely randomized design (CRD) factorial pattern (3x2x4). Factor G is a strain consisting of 3 levels: 1. G1 = Arabic chicken, 2. G2 = Super chicken, 3. G3 = Free-range chicken, with female sex Factor L is the type of cage which consists of 2 levels, namely: 1. L1 = slat floor; 2. L2 = litter floor. Animal feed consumption had a significant effect on floor type (P<0.05) and lines had a very significant effect (P<0.01), drinking water consumption, body weight gain and feed conversion did not have a significant effect on chicken growth. village. There was no effect of strain interaction with floor type, but the average feed consumption results showed the highest interaction was in G1L2 and the lowest score was in G3L2, while the average PBB of lines with floor type showed the highest interaction in G2L1 of 74.87 while the lowest G3L2 was 58.75 grams. The highest body weight gain on the slat floor was an average of 70.20 grams per head/week, for the super lines was 72.56 grams while efficient feed conversion was 4.48 and 4.48 litter floors. super strain 3.8 gram.
 

Box Lesion Isolation of the Left Atrial Posterior Wall with Radiofrequency Ablation Restricted in Predetermined Lines for the Treatment of Persistent Atrial Fibrillation: The Prognostic Role of Acute Interventional Outcome and Trigger Identification.

The left atrial posterior wall (PW) is known to be a critical substrate for the initiation and perpetuation of atrial fibrillation (AF) and has been explored as a target for catheter ablation, particularly in persistent AF (PerAF). In this retrospective study, we investigate the clinical outcome of patients with PerAF who underwent PW isolation (PWI) restricted in predetermined lines in addition to pulmonary vein isolation (PVI). One hundred consecutive patients (64 ± 9.1 years, 66% male, 20% with previous PVI ablation) underwent PWI in a box lesion setting for PerAF lasting >3 months (34% long-standing PerAF). PW triggers were defined as either foci from the PW that repeatedly induced AF or as isolated AF or atrial tachycardia (AT) within the PW. After a mean follow-up period of 25.6 ± 6.7 months, 61% of the patients remained in sinus rhythm after the last procedure. In 79 patients, the PW was successfully isolated, while, in 21 patients, complete isolation was not possible due to failure in completion of the roof line (n = 16), the floor line (n = 7), or both (n = 2). Patients with incomplete isolation had similar AF/AT recurrence rates compared to those with complete PWI. In 12 patients, PW triggers were identified, and PWI in these patients was shown to have a significantly better prognosis in terms of sinus rhythm maintenance (P = .031). Failure of complete PWI does not predispose a patient to an inferior outcome nor is it responsible for iatrogenic ATs. The presence of AF triggers within the PW leads to a particularly favorable result after box lesion isolation.

Quantifying acoustic performance and embodied carbon of acoustic solutions for mass timber buildings: Comparing common approaches around the globe

As mass timber continues to increase in popularity as a building method to shifting away from high embodied carbon concrete structures to utilize wood as a renewable and lower embodied material. As whole building life cycle assessments (LCA) become more essential in meeting environmental emissions targets and qualifying for sustainability linked financing, quantifying the embodied carbon of both the structure and all other elements is necessary. The acoustic challenges of mass timber have been well documented and studied in previous works with a range of solutions now commonly utilized. Like most elements of construction, regionality results in different techniques being more popular and practical in different parts of the world. This work will compare the airborne and structure borne sound transmission and associated embodied carbon of four common acoustic designs for mass timber construction: floating concrete toppings, isolated board and batten floor systems, isolated dry floor linings, and raised access floors.

Corrosion Detection and Surface Repair with Coatings on Condensate Storage Tanks Internal Surfaces

In the Nuclear power plant Krško, there are two single hull condensate storage tanks with floating diaphragm each containing up to 757 m3 of demineralized water. The main purpose of these two storage tanks is to provide a capacity of cooling water for cooling the reactor coolant system via steam generators with the use of auxiliary feedwater pumps. This is a very important function from the safety point of view and that is the reason that both storage tanks are listed as safety class 3 components. It is also possible to fill up the condensate system if other means are not available. Condensate storage tanks are subject to periodic testing and periodic inspections to determine the condition of the components. Both tanks are in operation since the start-up of the powerplant, are located outside, and are exposed to different degradation processes. There was a concern that the tanks are leaking because there were often small puddles of water near the tanks. There were no changes in the levels of tanks. The design of tanks is a single hull, so there is no indication if a small leak is present.In the outage 2018, both tanks were emptied and examined with NDE methods to find any corrosion damage of bottom plates and any untight spots on adjacent welds.The article is about the NDE methods that were used (Magnetic Flux Leakage, Ultrasonic and Vacuum Box inspection) to determine the condition of the floor plates and adjacent welds as well as the process of internal surface reparation with coatings. Process of coatings qualification for use in safety class components is also explained: dedication process for material up-grade from non-safety related to safety-related because CY tank linings are classified as safety-related according to RG 1.54, rev 2 and corresponding ASTM standards and NEK technical specification SP-A5001. All activities for surface repair with coatings shall comply with safety-related requirements. Also, extensive immersion tests with selected and specially defined parameters were performed in NEK chemical laboratory in order to select the most suitable coating system for surface repair of CY tank floor lining. Further details concerning immersion tests are presented below.

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 >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.

Epicardial Roof-Dependent Macro–Re-Entrant Tachycardia After Ablation of Atrial Fibrillation: Electrophysiological Characteristics and Ablation

BackgroundEpicardial roof-dependent macro–re-entrant tachycardias (epi-RMAT) after catheter ablation of persistent atrial fibrillation are not rare but the prevalence and characteristics remain unclear. ObjectivesThe purpose of this study was to investigate the prevalence, electrophysiological characteristics and ablation strategy of recurrent epi-RMATs after ablation of atrial fibrillation. MethodsA total of 44 consecutive patients with 45 roof-dependent RMATs after atrial fibrillation ablation were enrolled. High-density mapping and appropriate entrainment were performed to diagnose epi-RMATs. ResultsEpi-RMAT was identified in 15 patients (34.1%). Under the right lateral view, the activation pattern can be briefly classified into clockwise re-entry (n = 4), counterclockwise re-entry (n = 9), and bi-atrial re-entry (n = 2). Five (33.3%) had a pseudofocal activation pattern. All epi-RMATs had continuous slow or no conduction zone with a mean width of 21.3 ± 12.3 mm traversing both pulmonary antra, and 9 (60.0%) had missing cycle length of >10% actual cycle length. Compared with endocardial RMAT (endo-RMAT), epi-RMAT required longer ablation time (9.60 ± 4.98 minutes vs 3.68 ± 3.42 minutes; P < 0.001), more floor line ablation (93.3% vs 6.7%; P < 0.001), and electrogram-guided posterior wall ablation (78.6% vs 3.3%; P < 0.001). Electric cardioversion was required in 3 patients (20.0%) with epi-RMATs, whereas all endo-RMATs were terminated by radiofrequency applications (P = 0.032). Posterior wall ablation was performed under esophagus deviation in 2 patients. We did not observe a significant difference in the recurrence of atrial arrhythmias between patients with epi-RMATs and endo-RMATs after the procedure. ConclusionsEpi-RMATs are not uncommon after roof or posterior wall ablation. An explicable activation pattern with a conduction obstacle in the dome and appropriate entrainment is critical for the diagnosis. The effectiveness of posterior wall ablation may be restricted by the risk of esophagus impairment.

Outcomes of additional substrate modification in de novo atrial fibrillation ablation

Abstract Background Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) ablation. Data regarding additional substrate modification has been conflicting, both in paroxysmal and persistent atrial fibrillation. Purpose To assess the effect of additional linear substrate modification during de novo AF ablation on AF recurrence. Methods We reviewed 1575 AF ablations in 1254 patients from January 2013 to June 2021 at a single academic medical center. There were 1096 de novo ablations. We defined substrate modification as linear ablations including cavotricuspid isthmus (CTI), superior vena cava isolation, intercaval line, mitral isthmus, and left atrial roof and floor lines. We evaluated clinical and procedural characteristics to identify risk factors for AF recurrence and complications. Patients were followed for a minimum of 6 months. Results The 1096 de novo ablations included 65.5% males with mean age 61.1 years, mean BMI 31.3, 81.8% paroxysmal AF and 18.2% persistent AF. There were four AF ablation subgroups: PVI alone (41.6%), PVI and CTI ablation (37.1%), PVI with CTI and additional substrate modification (15.6%), and PVI with substrate modification without CTI ablation (5.7%). Overall, AF recurred in 36.9% cases. AF recurrence with PVI only ablation was 41% compared to 32.7% in patients with PVI and CTI ablation (p=0.02). When looking at patients with paroxysmal and persistent AF, results were similar, with decreased AF recurrence with the addition of CTI ablation in both paroxysmal (37.3% v. 29.2%, p=0.03) and persistent AF (58.1% v. 40.0%, p=0.02). Additional substrate modification did not result in significant difference in outcome in either paroxysmal or persistent AF (Figure 1). Conclusions In de novo AF ablations, addition of CTI ablation to de novo PVI ablation is associated with lower AF recurrence in both paroxysmal and persistent AF. Additional linear substrate modification did not impact outcomes. Funding Acknowledgement Type of funding sources: None.

Gaps after linear ablation of persistent atrial fibrillation (Marshall-PLAN): Clinical implication

Beyond pulmonary vein (PV) isolation, anatomic isthmus transection is an adjunctive strategy for persistent atrial fibrillation. Data on the durability of multiple lines of block remain scarce. The purpose of this study was to evaluate the impact of gaps within such a lesion set. We followed 291 consecutive patients who underwent (1) vein of Marshall ethanol infusion, (2) PV isolation, and (3) mitral, cavotricuspid, and dome isthmus transection. Dome transection relied on 2 distinct strategies over time: a single roof line with touch-ups applied in case of gap demonstrated by conventional maneuvers (first leg), and an alternative floor line if the roof line exhibited a gap during high-density mapping with careful electrogram reannotation (second leg). Twelve-month sinus rhythm maintenance was 70% after 1 procedure and 94% after 1 or 2 procedures. Event-free survival after the first procedure was lower in case of residual gaps within the lesion set (log-rank, P = .004). Delayed gaps were found in 94% of a second procedure performed in the 69 patients relapsing despite a complete lesion set with PV gaps increasing the risk of recurrence of atrial fibrillation (67% vs 34%; P = .02) and anatomic isthmus gaps supporting a majority of atrial tachycardias (60%). Between the first leg and the second leg, a significant decrease was found in roof lines considered blocked during the first procedure (99% vs 78%; P < .001) and in delayed dome gaps observed during a second procedure (68% vs 43%; P = .05). Gaps are arrhythmogenic and can be reduced by optimized ablation and assessment of lines of block. Closing these gaps improves sinus rhythm maintenance.

Prospective evaluation of local impedance drop to guide left atrial posterior wall ablation with high power.

Local impedance (LI) drop predicts acute conduction block during pulmonary vein isolation (PVI). Whether the LI drop predicts also the achievement of left atrial posterior wall isolation (LAPWI) in persistent atrial fibrillation (PersAF) patients is unknown. We evaluated the efficacy and the safety of LI drop-guided LAPW ablation by using high power (50 watts) and investigated the impact of ablation parameters on the LI drop. We included consecutive PersAF patients underwent PVI and both roof line and floor line completion to achieve LAPWI with a novel contact force (CF)- and LI-featured catheter (IntellaNAV Stablepoint™). For each radiofrequency (RF) application, we targeted a LI drop of 25 ohms. Out of 30 patients, first-pass floor line block was achieved in 26 (87%) and first-pass roof line block in 17 (57%), resulting in first-pass LAPWI in 14 patients (47%). After touch-up ablations, LAPWI was achieved in 28 patients (93%) with endocardial ablation only. No procedural nor 1-month complications occurred. Overall, 877 RF applications were delivered: 787 ablation tags (89%) were associated with acute conduction block, while 90 (11%) were located at sites of acute gaps in either the roof or floor line. LI drop values were greater at segments with acute block than those with gaps (p < 0.001). At multivariable analysis, only LI drop and RF time remained independently associated with the acute block (p < 0.001; p = 0.001). LI drop-guided LAPWI at a fixed power of 50W was effective and did not lead to complications. LI drop was the most important predictor of acute conduction block.

Ablation index-guided 50W radiofrequency ablation for left atrial posterior wall isolation in atrial fibrillation

BackgroundAblation index (AI)-guided ablation for posterior wall isolation (PWI) using high-power, short-duration remains untested. We sought to evaluate the acute outcomes of AI-guided 50 W ablation vs. conventional ablation, and investigate the differences in relationship between contact force (CF), time and AI in both groups. MethodsConsecutive patients undergoing first-time AI-guided ablation with PWI using either 50 W or 35–40 W ablation were enrolled. Acute procedural metrics and individual lesion level ablation data were compared between groups. Results40 patients (50 W: n = 20, 35–40 W: n = 20) with atrial fibrillation were included. Total procedure time was significantly reduced with 50 W (120 vs. 143 mins, p = 0.004) and there was a trend toward decreased ablation time (22 vs. 28 mins, p = 0.052). First pass and acute success of PWI were comparable between the 50 W and 35–40 W groups (10 vs. 8 patients, p = 0.525 and 20 vs. 19 patients, p = 1.000, respectively). Individual lesion analysis of all 959 RF applications (50 W: n = 458, 35–40 W: n = 501) demonstrated that 50 W ablation led to lower ablation time per lesion (10.4 vs. 13.0s, p < 0.001), and increased AI (471 vs. 461, p < 0.001) and impedance drop (7.4 vs. 6.9ohms, p = 0.007). Excessive ablations (AI>600 for roof line; AI>500 elsewhere) were more frequently observed in the 50 W group (9.0% vs. 4.6%, p = 0.007). CF had very good discriminative capability for excessive ablation in both groups. At 50 W, limiting the CF to <10 g reduced the number of excessive ablations on the floor line and within the posterior box to 12% and 4%,respectively. Recurrence of atrial arrhythmias at 12 months were comparable between the groups. ConclusionAI-guided 50 W RF ablation reduces the ablation time of individual lesions and total procedure time without compromising first pass and acute success rates of PWI or 12-month outcomes compared to conventional powers.

Differences in the durability of left atrial posterior wall isolation based on the isolation process.

The best strategy for durable left atrial posterior wall isolation (PWI) after completion of pulmonary vein isolation (PVI) is not yet determined. This study aimed to examine the differences in the durability of PWI based on the isolation process and the predictors of the reconduction of PWI. Among the 221 patients (mean age, 65 ± 11years) with consecutive non-paroxysmal atrial fibrillation (AF) who completed PVI and PWI, 50 patients undergoing repeat AF ablation were enrolled and divided into the following groups based on how PWI was achieved at the initial procedure: by only the first line on the roof and floor line (group A), by additional gap ablation to the first line or second liner ablation next to the first line (group B), and by adjunct ablation inside the PW revealing the earliest activation (group C). Reconduction of PWI occurred in 24 of the 50 patients (48%). The durability of PWI in groups A, B, and C was 81% (17 of 21 patients), 75% (6 of 8 patients), and 14% (3 of 21 patients), respectively (p < 0.01). In a multivariate analysis, the ablation inside the PW for PWI was the independent predictor of the reconduction of PWI (p < 0.001). PWI achieved by the ablation inside the PW resulted in a high rate of reconduction. It may be necessary to aim to achieve the PWI without ablating the inside of the PW to prevent reconduction.

Sex Differences in Ablation Strategy, Lesion Sets, and Complications of Catheter Ablation for Atrial Fibrillation: An Analysis From the GWTG-AFIB Registry

When presenting for atrial fibrillation (AF) ablation, women, compared with men, tend to have more nonpulmonary vein triggers and advanced atrial disease. Whether this informs differences in AF ablation strategy is not well described. We aimed to characterize ablation strategy and complications by sex, using the Get With The Guidelines-AF registry. From the Get With The Guidelines-AF registry ablation feature, we included patients who underwent initial AF ablation procedure between January 7, 2016, and December 27, 2019. Patients were stratified based on AF type (paroxysmal versus nonparoxysmal) and sex. We compared patient demographics, ablation strategy, and complications by sex. Among 5356 patients from 31 sites who underwent AF ablation, 1969 were women (36.8%). Women, compared with men, were older (66.8±9.6 versus 63.4±10.6, P<0.0001) and were more likely to have paroxysmal AF (59.4% versus 49.5%, P<0.0001). In women with nonparoxysmal AF, left atrial linear ablation was more frequent (roof line: 53.9% versus 45.3%, P=0.0002; inferior mitral isthmus line: 10.2% versus 7.0%, P=0.01; floor line: 46.1% versus 40.6%, P=0.02) than in men. In multivariable analysis, the association between patient sex and complications from ablation was not statistically significant. In this US wide AF ablation quality improvement registry, women with nonparoxysmal AF were more likely to receive adjunctive lesion sets compared with men. These findings suggest that patient sex may inform ablation strategy in ways that may not be strongly supported by evidence and emphasize the need to clarify optimal ablation strategies by sex.