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Aims: Pulsed-field ablation (PFA) is a novel, myocardial-selective, non-thermal ablation modality used to target cardiac arrhythmias. Although prompt electrogram (EGM) signal disappearance is observed immediately after PFA application in the pulmonary veins, whether this finding results in adequate transmural lesions is unknown. The aim of this study is to check whether application repetition and catheter-tissue contact impact lesion formation during PFA., Methods and Results: A circular loop PFA catheter was used to deliver repeated energy applications with various levels of contact force. A benchtop vegetal potato model and a beating heart ventricular myocardial model were utilized to evaluate the impact of application repetition, contact force, and catheter repositioning on contiguity and lesion depth. Lesion development occurred over 18 h in the vegetal model and over 6 h in the porcine model. Lesion formation was found to be dependent on application repetition and contact. In porcine ventricles, single and multiple stacked applications led to a lesion depth of 3.5 ± 0.7 and 4.4 ± 1.3 mm, respectively (P = 0.002). Furthermore, the greater the catheter-tissue contact, the more contiguous and deeper the lesions in the vegetal model (1.0 ± 0.9 mm with no contact vs. 5.4 ± 1.4 mm with 30 g of force; P = 0.0001)., Conclusion: Pulsed-field ablation delivered via a circular catheter showed that both repetition and catheter contact led independently to deeper lesion formation. These findings indicate that endpoints for effective PFA are related more to PFA biophysics than to mere EGM attenuation., Competing Interests: Conflict of interest: L.D.B. is a consultant for Stereotaxis, Biosense Webster, Boston Scientific, Abbott Medical, I-Rhythm, Siemens Medtronic, AtriCure, Biotronik, and Zoll. T.G., E.B., and V.G. are employees of Biosense Webster, Inc., a Johnson & Johnson company. All remaining authors have declared no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: The effect of contact force (CF) on lesion formation is not clear during pulsed field ablation (PFA). The aim of this study was to evaluate the impact of CF, PFA, and their interplay through the PFA index (PF index) formula on the ventricular lesion size in swine., Methods: PFA was delivered through the CF-sensing OMNYPULSE catheter. Predefined PFA applications (×3, ×6, ×9, and ×12) were delivered maintaining low (5-25 g), high (26-50 g), and very high (51-80 g) CFs. First, PFA lesions were evaluated on necropsy in 11 swine to investigate the impact of CF/PFA-and their integration in the PF index equation-on lesion size (study characterization). Then, 3 different PF index thresholds-300, 450, and 600-were tested in 6 swine to appraise the PF index accuracy to predict the ventricular lesion depth (study validation)., Results: In the study characterization data set, 111 PFA lesions were analyzed. CF was 32±17 g. The average lesion depth and width were 3.5±1.2 and 12.0±3.5 mm, respectively. More than CF and PFA dose alone, it was their combined effect to impact lesion depth through an asymptotically increasing relationship. Likewise, not only was the PF index related to lesion depth in the study validation data set (r 2 =0.66; P <0.001) but it also provided a prediction accuracy of the observed depth of ±2 mm in 69/73 lesions (95%)., Conclusions: CF and PFA applications play a key role in lesion formation during PFA. Further studies are required to evaluate the best PFA ablation settings to achieve transmural lesions., Competing Interests: Disclosures Dr Di Biase is a consultant for Stereotaxis, Biosense Webster, Boston Scientific, Abbott Medical, and I-Rhythm and has received speaker honoraria/travel from Medtronic, AtriCure, Biotronik, Baylis Medical, and Zoll. Dr Hsu has received honoraria from Medtronic, Abbott, Boston Scientific, Biotronik, Janssen Pharmaceuticals, Bristol-Myers Squibb, Pfizer, Sanofi, Zoll Medical, AltaThera, iRhythm, Acutus Medical, Galvanize Therapeutics, vizAI, and Biosense Webster, research grants from Biotronik and Biosense Webster, and has equity interest in Vektor Medical. V. Grupposo, C. Beeckler, and Drs Sharma and Govari are employees at Biosense Webster. The other authors report no conflicts.

Background: Pulsed field ablation (PFA) has emerged as an alternative to radiofrequency ablation. However, data on focal point-by-point PFA are scarce. The aim of this study was to compare lesion durability and collateral damage between focally delivered unipolar/biphasic PFA versus radiofrequency in swine., Methods: Eighteen swine were randomized to low-dose PFA, high-dose PFA, and radiofrequency using a multimodality generator. Radiofrequency delivered by market-available generator served as control group. A contact force-sensing catheter was used to focally deliver PFA/radiofrequency at the pulmonary veins and other predefined sites in the atria. Animals were remapped postprocedurally and 28 days postablation to test lesion durability followed by gross necroscopy and histology., Results: All targeted sites were successfully ablated (contact force value, 13.9±4.1 g). Follow-up remapping showed persistent pulmonary vein isolation in all animals (100%) with lesion durability at nonpulmonary vein sites proven in most (98%). Regardless of the energy source used, the lesion size was similar across the study groups. Transmurality was achieved in 95% of targeted sites and 100% at pulmonary veins. On histology, PFA animals showed more mature scar formation than their radiofrequency counterpart without myocardial necrosis or inflammation. Finally, no sign of collateral damage was observed in any of the groups., Conclusions: In a randomized preclinical study, focally delivered unipolar/biphasic PFA guided by contact force values was associated with durable lesions on chronic remapping and with mature scar formation on histology without signs of collateral injury on necroscopy. Further studies are needed to investigate the long-term feasibility of this new approach to atrial fibrillation treatment., Competing Interests: Disclosures Dr Di Biase is a consultant for Stereotaxis, Biosense Webster, Boston Scientific, Abbott Medical, and I-Rhythm and has received speaker honoraria/travel from Medtronic, Atricure, Biotronik, Baylis Medical, and Zoll. V. Grupposo, Drs Marazzato, Farshchi-Heydari, Sharma, C. Beeckler, and Dr Govari are Biosense Webster Employees. The other authors report no conflicts.

Aims: Intracardiac echocardiography (ICE) is a useful but operator-dependent tool for left atrial (LA) anatomical rendering during atrial fibrillation (AF) ablation. The CARTOSOUND FAM Module, a new deep learning (DL) imaging algorithm, has the potential to overcome this limitation. This study aims to evaluate feasibility of the algorithm compared to cardiac computed tomography (CT) in patients undergoing AF ablation., Methods and Results: In 28 patients undergoing AF ablation, baseline patient information was recorded, and three-dimensional (3D) shells of LA body and anatomical structures [LA appendage/left superior pulmonary vein/left inferior pulmonary vein/right superior pulmonary vein/right inferior pulmonary vein (RIPV)] were reconstructed using the DL algorithm. The selected ultrasound frames were gated to end-expiration and max LA volume. Ostial diameters of these structures and carina-to-carina distance between left and right pulmonary veins were measured and compared with CT measurements. Anatomical accuracy of the DL algorithm was evaluated by three independent electrophysiologists using a three-anchor scale for LA anatomical structures and a five-anchor scale for LA body. Ablation-related characteristics were summarized. The algorithm generated 3D reconstruction of LA anatomies, and two-dimensional contours overlaid on ultrasound input frames. Average calculation time for LA reconstruction was 65 s. Mean ostial diameters and carina-to-carina distance were all comparable to CT without statistical significance. Ostial diameters and carina-to-carina distance also showed moderate to high correlation (r = 0.52-0.75) except for RIPV (r = 0.20). Qualitative ratings showed good agreement without between-rater differences. Average procedure time was 143.7 ± 43.7 min, with average radiofrequency time 31.6 ± 10.2 min. All patients achieved ablation success, and no immediate complications were observed., Conclusion: DL algorithm integration with ICE demonstrated considerable accuracy compared to CT and qualitative physician assessment. The feasibility of ICE with this algorithm can potentially further streamline AF ablation workflow., Competing Interests: Conflict of interest: L.D.B. is a consultant for Stereotaxis, Biosense Webster, Boston Scientific, Abbott Medical; has received speaker honoraria/travel from Medtronic, Atricure, Biotronik, Baylis Medical, and Zoll. G.H., D.H., R.A.M., J.A., G.C., and R.U. are employees of Biosense Webster, Inc. The remaining authors report no conflict of interest., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: A significant role of the left atrial appendage (LAA) in the genesis of atrial fibrillation (AF) has been described. Left atrial appendage electrical isolation (LAAEI) confers substantial long-term clinical benefits. Nevertheless, the left phrenic nerve (LPN) is in the vicinity of the LAA and can be injured during radiofrequency ablation at the ostial level., Objective: The purpose of this study was to describe our experience mapping the LPN, its anatomic relationships to the LAA and alternative approaches to isolate this structure when the LPN is located at the LAA ostium., Methods: Patients undergoing LAAEI for nonparoxysmal AF were included in this study. We attempted to localize the LPN with high-output pacing (20 mA/2 ms). Cases were classified into 4 groups (distal, middle, proximal segment and unmappable) based on the position of the LPN in electroanatomic mapping in the posterior wall of the LAA., Results: A total of 66 cases were included in this study. The LPN was mapped in the distal segment in 27 cases (40.9%); in the middle segment in 22 (33.3%); and at the proximal segment/ostium in 3 (4.5%); the LPN was unmappable in 14 cases (21.2%). In the 3 patients in whom the LPN was at the ostial level or crossing the ostium, segmental LAAEI was attempted in 2, with successful LAAEI achieved in 1 case. There was no LPN injury., Conclusion: LPN mapping is feasible and should be routinely performed to prevent LPN injury during LAAEI., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Objectives: This study sought to determine the distance between the anterior wall of the left atrial appendage (LAA) ostium to the left main coronary artery (LMCA) and the left circumflex artery (LCx) in patients undergoing left atrial appendage electrical isolation (LAAEI)., Background: LAAEI improves outcomes in nonparoxysmal atrial fibrillation ablation. There is a potential risk of damaging the LMCA and the LCx during LAAEI., Methods: Patients undergoing LAAEI during the period between January 1, 2017 and October 31, 2018, were included in this study. Patients underwent cardiac computed tomography prior to ablation. The position of the LAA was analyzed. The closest distances between the LMCA, its bifurcation, LCx, and the anterior wall of the LAA ostium were measured. Additionally, imaging integration was performed to localize these vessels and catheter ablation was performed at least 5 mm away., Results: A total of 74 patients (mean age: 68 ± 9.5 years; male 54%) who underwent LAAEI were included. The mean distance from the anterior wall of the LAA ostium to the LMCA was 7.88 ± 2.8 mm, to the LMCA bifurcation was 9.24 ± 4.40 mm, and to the LCx was 10.03 ± 4.56 mm. The LCx artery was found along the LAA ostium in 98% of the cases, whereas the LMCA was found in only 48.6%. No coronary damage or vasospasm was observed after performing LAAEI., Conclusions: A detailed imaging integration with cardiac computed tomography, electroanatomic mapping, and CARTOSOUND reconstructions to accurately define the anatomical relationship between the LMCA and LCx and the anterior edge of the LAA ostium should be performed prior to delivering radiofrequency energy during LAAEI. When the distance on cardiac computed tomography between the LAA ostium and left coronary arteries is >10 mm, intraprocedural localization of these vessels may be not necessary., (Copyright © 2020. Published by Elsevier Inc.)

Objectives: This study assessed the incremental benefit of uninterrupted direct oral anticoagulants (DOACs) versus uninterrupted vitamin K antagonists (VKAs) for catheter ablation (CA) of nonvalvular atrial fibrillation (NVAF) on 3 primary outcomes: major bleeding events (MBEs), minor bleeding events, and thromboembolic events (TEs). The secondary outcome was post-procedural silent cerebral infarction (SCI) as detected by brain cardiac magnetic resonance., Background: As a class, evidence of the benefits of DOACs versus VKAs during CA of AF is scant., Methods: A systematic review of Medline, Cochrane, and Embase was done to find all randomized controlled trials in which uninterrupted DOACs were compared against uninterrupted VKAs for CA of NVAF. A fixed-effect model was used, except when I 2 was ≥25, in which case, a random effects model was used., Results: The benefit of uninterrupted DOACs over VKAs was analyzed from 6 randomized control trials that enrolled a total of 2,256 patients (male: 72.7%) with NVAF, finding significant benefit in MBEs (relative risk [RR]: 0.45; 95% confidence interval [CI]: 0.20 to 0.99; p = 0.05). No significant differences were found in minor bleeding events (RR: 1.12; 95% CI: 0.87 to 1.43; p = 0.39), TEs (RR: 0.75; 95% CI: 0.26 to 2.14; p = 0.59), or post-procedural SCI (RR: 1.09; 95% CI: 0.80 to 1.49; p = 0.58)., Conclusions: An uninterrupted DOACs strategy for CA of AF appears to be safer than uninterrupted VKAs with a decreased rate of major bleeding events. There are no significant differences among the other outcomes. DOACs should be offered as a first-line therapy to patients undergoing CA of AF, due to their lower risk of major bleeding events, ease of use, and fewer interactions., (Copyright © 2019 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: This study sought to determine whether combined endocardial-epicardial (endo-epi) ablation was superior to endocardial only ablation in patients with scar-related ventricular tachycardia (VT)., Background: Limited single-center studies suggest that combined endo-epi ablation strategy may be superior to endocardial ablation (endo) alone in patients with nonischemic cardiomyopathy (NICM) and arrhythmogenic right ventricular cardiomyopathy (ARVC), and ischemic cardiomyopathy (ICM)., Methods: A systematic review of Medline, Cochrane, and Embase databases was performed for studies that reported outcomes comparing endo-epi with endo VT ablation alone., Results: Seventeen studies consisting of 975 patients were included (mean 56 ± 10 years of age; 79% male; NICM in 36.6%; ICM in 32.8%; and ARVC in 30.6%). After a mean follow-up of 27 ± 21 months, endo-epi ablation was associated with a 35% reduction in risk of VT recurrence compared with endocardial ablation alone (risk ratio [RR]: 0.65; 95% confidence interval [CI]: 0.55 to 0.78; p < 0.001). Sensitivity analysis showed lower risk of VT recurrence in ICM (RR: 0.43; 95% CI: 0.28 to 0.67; p = 0.0002) and ARVC (RR: 0.59; 95% CI: 0.43 to 0.82; p = 0.0002), with a nonsignificant trend in NICM (RR: 0.87; 95% CI: 0.70 to 1.08; p = 0.20). Endo-epi, compared with endo ablation, was associated with reduced all-cause mortality (RR: 0.56; 95% CI: 0.32 to 0.97; p = 0.04). Acute procedural complications were higher with the endo-epi approach (RR: 2.62; 95% CI: 0.91 to 7.52; p = 0.07)., Conclusions: This meta-analysis suggests that a combined endo-epi ablation is associated with a lower risk of VT recurrence and subsequent mortality than endo only VT ablation in patients with scar-related VT. Procedural complications, however, are higher with the endo-epi approach., (Crown Copyright © 2019. Published by Elsevier Inc. All rights reserved.)

Aims: To assess the incremental benefit of uninterrupted direct oral anticoagulants (DOACs) vs. uninterrupted vitamin K antagonists (VKA) for catheter ablation (CA) of non-valvular atrial fibrillation (NVAF) on three primary outcomes: major bleeding, thrombo-embolic events, and minor bleeding. A secondary outcome was post-procedural silent cerebral infarction (SCI) as detected by brain magnetic resonance imaging., Methods and Results: A systematic review of Medline, Cochrane, and Embase was done to find all randomized controlled trials (RCTs) in which uninterrupted DOACs were compared against uninterrupted VKA for CA of NVAF. A fixed-effect model was used, with the exception of the analysis regarding major bleeding events (I2 > 25), for which a random effects model was used. The benefit of uninterrupted DOACs over VKA was analysed from four RCTs that enrolled a total of 1716 patients (male: 71.2%) with NVAF. Of these, 1100 patients (64.1%) had paroxysmal atrial fibrillation. No significant benefit was seen in major bleeding events [risk ratio (RR) 0.54, 95% confidence interval (95% CI) 0.29-1.00; P = 0.05]. No significant differences were found in minor bleeding events (RR 1.11, 95% CI 0.82-1.52; P = 0.50), thrombo-embolic events (RR 0.74, 95% CI 0.26-2.11; P = 0.57), or post-procedural SCI (RR 1.06, 95% CI 0.74-1.53; P = 0.74)., Conclusion: An uninterrupted DOACs strategy for CA of NVAF appears to be as safe as uninterrupted VKA without a significantly increased risk of minor or major bleeding events. There was a trend favouring DOACs in terms of major bleeding. Given their ease of use, fewer drug interactions and a similar security and effectiveness profile, DOACs should be considered first line therapy in patients undergoing CA for NVAF.

Bundle branch reentrant ventricular tachycardia (BBRVT) is characterized by a unique, fast (200-300 beats/min), monomorphic wide complex tachycardia (WCT) associated with syncope, hemodynamic compromise, and cardiac arrest. It is challenging to diagnose, requiring a His bundle recording and specific pacing maneuvers. The overall incidence has been reported to be up to 20% among patients with non-ischemic cardiomyopathy (NICM) undergoing electrophysiologic studies. We report a case of BBRVT in a patient with ischemic cardiomyopathy (ICM) presenting as a WCT with recurrent implantable-cardioverter-defibrillator (ICD) shocks. We describe all the characteristic features of BBRVT and discuss its differential. We also discuss the role of ablation for this condition.