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Aims: Pulsed field ablation (PFA) has significant advantages over conventional thermal ablation of atrial fibrillation (AF). This first-in-human, single-arm trial to treat paroxysmal AF (PAF) assessed the efficiency, safety, pulmonary vein isolation (PVI) durability and one-year clinical effectiveness of an 8 Fr, large-lattice, conformable single-shot PFA catheter together with a dedicated electroanatomical mapping system., Methods and Results: After rendering the PV anatomy, the PFA catheter delivered monopolar, biphasic pulse trains (5-6 s per application; ∼4 applications per PV). Three waveforms were tested: PULSE1, PULSE2, and PULSE3. Follow-up included ECGs, Holters at 6 and 12 months, and symptomatic and scheduled transtelephonic monitoring. The primary and secondary efficacy endpoints were acute PVI and post-blanking atrial arrhythmia recurrence, respectively. Invasive remapping was conducted ∼75 days post-ablation. At three centres, PVI was performed by five operators in 85 patients using PULSE1 (n = 30), PULSE2 (n = 20), and PULSE3 (n = 35). Acute PVI was achieved in 100% of PVs using 3.9 ± 1.4 PFA applications per PV. Overall procedure, transpired ablation, PFA catheter dwell and fluoroscopy times were 56.5 ± 21.6, 10.0 ± 6.0, 19.1 ± 9.3, and 5.7 ± 3.9 min, respectively. No pre-defined primary safety events occurred. Upon remapping, PVI durability was 90% and 99% on a per-vein basis for the total and PULSE3 cohort, respectively. The Kaplan-Meier estimate of one-year freedom from atrial arrhythmias was 81.8% (95% CI 70.2-89.2%) for the total, and 100% (95% CI 80.6-100%) for the PULSE3 cohort., Conclusion: Pulmonary vein isolation (PVI) utilizing a conformable single-shot PFA catheter to treat PAF was efficient, safe, and effective, with durable lesions demonstrated upon remapping., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Pulsed field ablation (PFA) is a novel energy form for the catheter ablation of cardiac arrhythmias, which uses electrical fields to mediate myocardial death via irreversible electroporation and other modalities. It is believed to offer relative tissue specificity, lowering - or even eliminating - the risk of complications associated with thermal energy, such as atrio-oesophageal fistulas. The proposed superior safety profile compared to thermal ablation has contributed to the enthusiastic implementation of PFA into clinical practice and is supported by early preclinical and clinical data. However, data about the effects of PFA on the oesophagus remain limited. This organ's susceptibility to PFA has important clinical ramifications and there are two highly relevant questions. First, is the oesophagus absolutely spared by PFA or is there susceptibility to injury at higher field strengths? Second, if oesophageal injury can occur, can atrio-oesophageal fistulas ensue? The aim of this article is to provide a literature review on the effects of PFA on the oesophagus and to address these questions based on the data described., Competing Interests: Disclosure: MN has received a scholarship from the German Research Foundation (Deutsche Forschungsgemeinschaft). JSK has received consultancy fees from Abbott, Biosense Webster, Boston Scientific, Cardiofocus and Medtronic, research grants from Affera, Cardiofocus and Pulse Bioscience and stock options from Affera. All other authors have no conflicts of interest to declare., (Copyright © The Author(s), 2024. Published by Radcliffe Group Ltd.)

Background: During electrophysiological mapping of tachycardias, putative target sites are often only truly confirmed to be vital after observing the effect of ablation. This lack of mapping specificity potentiates inadvertent ablation of innocent cardiac tissue not relevant to the arrhythmia. But if myocardial excitability could be transiently suppressed at critical regions, their suitability as targets could be conclusively determined before delivering tissue-destructive ablation lesions. We studied whether reversible pulsed electric fields (PF REV ) could transiently suppress electrical conduction, thereby providing a means to dissect tachycardia circuits in vivo., Methods: PF REV energy was delivered from a 9-mm lattice-tip catheter to the atria of 12 swine and 9 patients, followed by serial electrogram assessments. The effects on electrical conduction were explored in 5 additional animals by applying PF REV to the atrioventricular node: 17 low-dose (PF REV-LOW ) and 10 high-dose (PF REV-HIGH ) applications. Finally, in 3 patients manifesting spontaneous tachycardias, PF REV was applied at putative critical sites., Results: In animals, the immediate post-PF REV electrogram amplitudes diminished by 74%, followed by 78% recovery by 5 minutes. Similarly, in patients, a 69.9% amplitude reduction was followed by 84% recovery by 3 minutes. Histology revealed only minimal to no focal, superficial fibrosis. PF REV-LOW at the atrioventricular node resulted in transient PR prolongation and transient AV block in 59% and 6%, while PF REV-HIGH caused transient PR prolongation and transient AV block in 30% and 50%, respectively. The 3 tachycardia patients had atypical atrial flutters (n=2) and atrioventricular nodal reentrant tachycardia. PF REV at putative critical sites reproducibly terminated the tachycardias; ablation rendered the tachycardias noninducible and without recurrence during 1-year follow-up., Conclusions: Reversible electroporation pulses can be applied to myocardial tissue to transiently block electrical conduction. This technique of pulsed field mapping may represent a novel electrophysiological tool to help identify the critical isthmus of tachycardia circuits., Competing Interests: Disclosures Dr Reddy: Affera-Medtronic: consultant, equity (stock); other disclosures not related to this article are detailed in the Supplemental Material. Dr Koruth: Affera-Medtronic: grant support, stock, consultant. Dr Neuzil: Affera-Medtronic: grant support.

Background: We previously reported feasibility of irrigated needle ablation (INA) with a retractable 27-G end-hole needle catheter to treat nonendocardial ventricular arrhythmia substrate, an important cause of ablation failure., Objectives: The purpose of this study was to report outcomes and complications in our entire INA-treated population., Methods: Patients with recurrent sustained monomorphic ventricular tachycardia (VT) or high-density premature ventricular contractions (PVCs) despite radiofrequency ablation were prospectively enrolled at 4 centers. Endpoints included a 70% decrease in VT frequency or PVC burden decrease to <5,000/24 h at 6 months., Results: INA was performed in 111 patients (median: 2 failed prior ablations, 71% nonischemic heart disease, and left ventricular ejection fraction 36% ± 14%). INA acutely abolished targeted PVCs in 33 of 37 patients (89%), and PVCs were reduced to <5,000/day in 29 patients (78%). During 6-month follow-up, freedom from hospitalization was observed in 50 of 72 patients with VT (69%), and improvement or abolition of VT occurred in 47%. All patients received multiple INA applications, with more in the VT group than in the PVC group (median: 12 [IQR: 7-19] vs 7 [5-15]; P < 0.01). After INA, additional endocardial standard radiofrequency ablation was required in 23% of patients. Adverse events included 4 pericardial effusions (3.5%), 3 cases of (anticipated) atrioventricular block (2.6%), and 3 heart failure exacerbations (2.6%). During 6-month follow-up, 5 deaths occurred; none were procedure-related., Conclusions: INA achieves improved arrhythmia control in 78% of patients with PVCs and avoids hospitalization in 69% of patients with VT refractory to standard ablation at 6-month follow-up. Procedural risks are acceptable. (Intramural Needle Ablation for Ablation of Recurrent Ventricular Tachycardia, NCT01791543; Intramural Needle Ablation for the Treatment of Refractory Ventricular Arrhythmias, NCT03204981)., Competing Interests: Funding Support and Author Disclosures Dr Kurata has received a scholarship from the Japanese Heart Rhythm Society. Dr Hasegawa has received support from the International Rotary Fellowship of Healthcare Professionals. Dr Tedrow has received honoraria from Biosense Webster, Boston Scientific, and Abbott; and consulting fees from Thermedical Inc. Dr Dukkipati has received a research grant from Biosense Webster; and reports equity in Manual Surgical Sciences and Farapulse, which was acquired by Boston Scientific. Dr Richardson has received speaker honoraria from Medtronic; research funding from Medtronic and Abbott; and served as a consultant for Philips and Biosense Webster. Dr Kanagasundram has received speaker honoraria from Biosense Webster. Dr Koruth has received research grants from Affera, Farapulse, Cardiofocus, and Biosense Webster; consulting fees from Abbott, Farapulse, and Cardiofocus; and has equity in Affera. Dr John has received speaker honoraria from Abbott and Medtronic. Dr Sapp is a coholder of a patent for irrigated needle ablation with rights assigned to Brigham and Women’s Hospital; has received research grants from Biosense Webster and Abbott; and (modest) speaker or consulting honoraria from Medtronic, Abbott, Biosense Webster, and Varian. Dr Reddy has reported consulting fees and equity from Abalcon, Acutus Medical, Affera, Apama Medical, Aquaheart, Atacor, Autonomix, Backbeat, BioSig, Circa Scientific, Corvia Medical, Dinova-Hangzhou Nuomao Medtech Co, Ltd, East End Medical, EPD, Epix Therapeutics, EpiEP, Eximo, Fire1, Javelin, Kardium, Keystone Heart, LuxCath, Medlumics, Middlepeak, Nuvera, Sirona Medical, and Valcare; equity in Manual Surgical Sciences, Newpace, Surecor, Vizaramed, and Farapulse, which was acquired by Boston Scientific; and has received consulting fees from Abbott, Axon, Biosense Webster, Biotronic, Boston Scientific, Cardiofocus, Cardionomic, CardioNXT/AFTx, EBR, Impulse Dynamics, Medtronic, Philips, Pulse Biosciences, Stimda, and Thermedical. Dr Stevenson is a coholder of a patent for irrigated needle ablation with rights assigned to Brigham and Women’s Hospital; and has received speaking honoraria from Abbott, Boston Scientific, Biotronik, Biosense Webster, and Medtronic. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Because of its safety, "single-shot" pulsed field ablation (PFA) catheters have been developed for pulmonary vein isolation (PVI). However, most atrial fibrillation (AF) ablation procedures are performed with focal catheters to permit flexibility of lesion sets beyond PVI., Objectives: This study sought to determine the safety and efficacy of a focal ablation catheter able to toggle between radiofrequency ablation (RFA) or PFA to treat paroxysmal or persistent AF., Methods: In a first-in-human study, a focal 9-mm lattice tip catheter was used for PFA posteriorly and either irrigated RFA (RF/PF) or PFA (PF/PF) anteriorly. Protocol-driven remapping was at ∼3 months postablation. The remapping data prompted PFA waveform evolution: PULSE1 (n = 76), PULSE2 (n = 47), and the optimized PULSE3 (n = 55)., Results: The study included 178 patients (paroxysmal/persistent AF = 70/108). Linear lesions, either PFA or RFA, included 78 mitral, 121 cavotricuspid isthmus, and 130 left atrial roof lines. All lesion sets (100%) were acutely successful. Invasive remapping of 122 patients revealed improvement of PVI durability with waveform evolution: PULSE1: 51%; PULSE2: 87%; and PULSE3: 97%. After 348 ± 652 days of follow-up, the 1-year Kaplan-Meier estimates for freedom from atrial arrhythmias were 78.3% ± 5.0% and 77.9% ± 4.1% for paroxysmal and persistent AF, respectively, and 84.8% ± 4.9% for the subset of persistent AF patients receiving the PULSE3 waveform. There was 1 primary adverse event-inflammatory pericardial effusion not requiring intervention., Conclusions: AF ablation with a focal RF/PF catheter allows efficient procedures, chronic lesion durability, and good freedom from atrial arrhythmias-for both paroxysmal and persistent AF. (Safety and Performance Assessment of the Sphere-9 Catheter and the Affera Mapping and RF/PF Ablation System to Treat Atrial Fibrillation; NCT04141007 and NCT04194307)., Competing Interests: Funding Support and Author Disclosures This study was funded by a research grant from Affera Inc. Drs Reddy and Anter have received research grants from Affera, Inc. Drs Reddy, Anter, Koruth, and Jais hold stock options in Affera, Inc. Dr Reddy has served as a consultant to Kardium Inc (including Equity); is a consultant to Abbott, Ablacon, Acutus Medical, Affera-Medtronic, Apama Medical-Boston Scientific, APN Health, Aquaheart, Atacor, AtiAN, Autonomix, Axon Therapies, Backbeat, BioSig, Biosense-Webster, BioTel Heart, Biotronik, Boston Scientific, Cairdac, CardiaCare, Cardiofocus, Cardionomic, CardioNXT / AFTx, Circa Scientific, CoreMap, CoRISMA, Corvia Medical, Dinova-Hangzhou DiNovA EP Technology, East End Medical, EBR, EPD-Philips, EP Frontiers, Epix Therapeutics, EpiEP, Eximo, Farapulse-Boston Scientific, Fire1, Focused Therapeutics, Gore & Associates, HRT, Impulse Dynamics, Intershunt, Javelin, Keystone Heart, LuxMed, Medlumics, Medtronic, Middlepeak, Neutrace, Nuvera-Biosense Webster, Oracle Health, Philips, Pulse Biosciences, Restore Medical, Sirona Medical, SoundCath, and Valcare; and has equity from Ablacon, Acutus Medical, Affera-Medtronic, Apama Medical-Boston Scientific, APN Health, Aquaheart, Atacor, Autonomix, Axon Therapies, Backbeat, BioSig, CardiaCare, CardioNXT / AFTx, Circa Scientific, CoRISMA, Corvia Medical, Dinova-Hangzhou DiNovA EP Technology, East End Medical, EPD-Philips, EP Frontiers, Epix Therapeutics, EpiEP, Eximo, Farapulse-Boston Scientific, Focused Therapeutics, HRT, Intershunt, Javelin, Keystone Heart, LuxMed, Manual Surgical Sciences, Medlumics, Middlepeak, Neutrace, Newpace, Nuvera-Biosense Webster, Nyra Medical, Oracle Health, Restore Medical, Sirona Medical, SoundCath, Surecor, Valcare, and Vizaramed. Dr Peichl has received speaker honoraria from Abbott, Biosense Webster, Biotronik, Medtronic, MSD, Pfizer, and ProMed sro. Dr Anter has received research grants from Biosense Webster and Boston Scientific; and stock options from Itamar Medical. Dr Natale has received speaker honoraria from Boston Scientific, Biosense Webster, St. Jude Medical, Biotronik, and Medtronic; and is a consultant for Biosense Webster, Baylis Medical, Boston Scientific, Bristol-Myers Squibb, Biotronik, St. Jude Medical, and Medtronic. Dr Kautzner has received personal fees from Bayer, Biosense Webster, Boehringer Ingelheim, Medtronic, Merck Sharp & Dohme, Merit Medical, and St. Jude Medical (Abbott) for participation in scientific advisory boards; and has received speaker honoraria from Bayer, Biosense Webster, Biotronik, Boehringer Ingelheim, Boston Scientific, Daiichi Sankyo, Medtronic, Merck Sharp & Dohme, Mylan, Pfizer, ProMed sro, and St. Jude Medical (Abbott). All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Preclinical studies have revealed that pulsed field ablation (PFA) lesion dimensions increase with repetitive applications at a similar electric field., Objectives: This study investigated whether pulmonary vein isolation (PVI) durability varies with single vs repetitive pulsed field (PF) applications., Methods: Atrial fibrillation patients underwent PVI using a spherical multielectrode array PFA catheter delivered with a 19-F deflectable sheath under intracardiac echocardiographic guidance. Esophagogastroduodenoscopy and brain magnetic resonance imaging were performed within 1 to 3 days, and invasive remapping at ∼2 to 3 months., Results: The patient cohort (n = 21; age 63 ± 11 years; 67% women) underwent PVI in either of 2 groups: group 1 (n = 11)-single PF application/PV; and group 2 (n = 10)-3 PF applications/PV. In both groups, PVI was acutely successful in all (100%) patients. Despite significantly longer pulse delivery times (75.2 ± 7.4 s/patient vs 24.5 ± 5.5 s/patient) the procedure times (73.2 ± 13.7 minutes vs 93.7 ± 18.5 minutes) were shorter with group 2 vs group 1. There was no stroke/transient ischemic attack, pericardial effusion, phrenic nerve injury, or esophageal complications. Esophagogastroduodenoscopy was normal in both groups of patients (n = 9). Screening brain magnetic resonance imaging revealed asymptomatic cerebral lesions (diffusion weighted imaging+/fluid attenuated inversion recovery-) in 3 of 16 (18.7%) patients. PV remapping revealed durable PVI in 62.5% PVs in group 1 (n = 10), compared with all 100% PVs in group 2 (n = 9); this translates to all PVs being durably isolated in 30% vs 100% (P < 0.05) of patients in groups 1 and 2, respectively., Conclusions: In his first-in-human trial, the "single-shot" spherical array PFA catheter was shown to safely isolate PVs. Repetitive PF application is key for lesion consolidation to maximize PVI durability., Competing Interests: Funding Support and Author Disclosures Drs Neuzil and Koruth have received grant support from Kardium Inc. Dr Reinders is an employee of and holds stock in Kardium Inc. Dr Reddy has served as a consultant to Kardium Inc (including Equity); is a consultant to Abbott, Ablacon, Acutus Medical, Affera-Medtronic, Apama Medical-Boston Scientific, APN Health, Aquaheart, Atacor, AtiAN, Autonomix, Axon Therapies, Backbeat, BioSig, Biosense-Webster, BioTel Heart, Biotronik, Boston Scientific, Cairdac, CardiaCare, Cardiofocus, Cardionomic, CardioNXT / AFTx, Circa Scientific, CoreMap, CoRISMA, Corvia Medical, Dinova-Hangzhou DiNovA EP Technology, East End Medical, EBR, EPD-Philips, EP Frontiers, Epix Therapeutics, EpiEP, Eximo, Farapulse-Boston Scientific, Fire1, Focused Therapeutics, Gore & Associates, HRT, Impulse Dynamics, Intershunt, Javelin, Keystone Heart, LuxMed, Medlumics, Medtronic, Middlepeak, Neutrace, Nuvera-Biosense Webster, Oracle Health, Philips, Pulse Biosciences, Restore Medical, Sirona Medical, SoundCath, and Valcare; and has equity from Ablacon, Acutus Medical, Affera-Medtronic, Apama Medical-Boston Scientific, APN Health, Aquaheart, Atacor, Autonomix, Axon Therapies, Backbeat, BioSig, CardiaCare, CardioNXT / AFTx, Circa Scientific, CoRISMA, Corvia Medical, Dinova-Hangzhou DiNovA EP Technology, East End Medical, EPD-Philips, EP Frontiers, Epix Therapeutics, EpiEP, Eximo, Farapulse-Boston Scientific, Focused Therapeutics, HRT, Intershunt, Javelin, Keystone Heart, LuxMed, Manual Surgical Sciences, Medlumics, Middlepeak, Neutrace, Newpace, Nuvera-Biosense Webster, Nyra Medical, Oracle Health, Restore Medical, Sirona Medical, SoundCath, Surecor, Valcare, and Vizaramed. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: During atrial fibrillation ablations using thermal energy, the treatment effect is attributed to not just pulmonary vein isolation (PVI), but also to modulation of the autonomic nervous system by ablation of cardiac ganglionated plexi (GP)., Objectives: This study sought to assess the impact of pulsed field ablation (PFA) on the GP in patients undergoing PVI., Methods: In the retrospective phase, heart rate was assessed pre- versus post-PVI using PFA, cryoballoon ablation, or radiofrequency ablation. In the prospective phase, a pentaspline PFA catheter was used in a protocol: 1) pre-PFA, high-frequency stimulation (HFS) identified GP sites by vagal effects; 2) PVI was performed assessing for repetitive vagal effects over each set of PF applications; 3) mapping defined PVI extent to identify those GP in the ablation zone; and 4) repeat HFS at GP sites to assess for persistence of vagal effects., Results: Between baseline and 3 months, heart rates in the retrospective radiofrequency ablation (n = 40), cryoballoon (n = 40), and PFA (n = 40) cohorts increased by 8.9 ± 11.4, 11.1 ± 9.4, and -0.1 ± 9.2 beats/min, respectively (P= 0.01 PFA vs radiofrequency ablation; P= 0.01 PFA vs cryoballoon ablation). In the prospective phase, pre-PFA HFS in 20 additional patients identified 65 GP sites. During PFA, vagal effects were noted in 45% of first PF applications, persisting through all applications in 83%. HFS post-PFA reproduced vagal effects in 29 of 38 sites (76%) in low-voltage tissue., Conclusions: PFA has minimal effect on GP. Unlike with thermal ablation, the mechanism by which PFA treats atrial fibrillation is mediated solely by durable PVI., Competing Interests: Funding Support and Author Disclosures Dr Neuzil has received grant support from, and has served as a consultant to Farapulse Inc. Dr Dukkipati has equity in Farapulse Inc. Dr Reddy has served as a consultant to and owns equity in Farapulse Inc, Ableton, Acutus Medical, Affera, Apama Medical–Boston Scientific, APN Health, Aquaheart, Atacor, Autonomix, Axon Therapies, Backbeat, BioSig, CardiaCare, CardioNXT/AFTx, Circa Scientific, CoRISMA, Corvia Medical, Dinova-Hangzhou DiNOVA EP Technology, East End Medical, EPD-Philips, EP Frontiers, EPIX Therapeutics, EpiEP, Eximo, HRT, Intershunt, Javelin, Kardium, Keystone heart, LuxMed, Medlumics, Middlepeak, Neutrace, Nuvera-Biosense Weber, Oracle Health, Restore Medical, Sirona Medical, and Valcare, is a consultant to Abbott, AtiAN, Biosense-Webster, BioTel Heart, Biotronik, Boston Scientific, Cardiofocus, Cardionomic, CoreMap, EBR, Fire1, W. L. Gore and Associates, Impulse Dynamics, Medtronic, Philips, and Pulse Biosciences, and holds equity in Manual Surgical Sciences, Newpace, Surecor, and Vizaramed. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023. Published by Elsevier Inc.)

Competing Interests: Conflict of interest: V.Y.R. hold stock options in Farapulse, Inc. J.S.K. serves as a consultant to Farapulse. The other authors report no conflicts.

Background: Pulsed field ablation (PFA) has recently been shown to penetrate ischemic scar, but details on its efficacy, risk of arrhythmias, and imaging insights are lacking. In a porcine model of myocardial scar, we studied the ability of ventricular PFA to penetrate scarred tissue, induce ventricular arrhythmias, and assess the influence of QRS gating during pulse delivery., Methods: Of a total of 6 swine, 5 underwent coronary occlusion and 1 underwent radiofrequency ablation to create infarct scar and iatrogenic scar models, respectively. Two additional swine served as healthy controls. An 8 Fr focal PFA catheter was used to deliver bipolar, biphasic PFA (2.0 kV) lesions guided by electroanatomical mapping, fluoroscopy, and intracardiac echocardiography over both scarred and healthy myocardium. Swine underwent magnetic resonance imaging 2-7 days post-PFA., Results: PFA successfully penetrated scar without significant difference in lesion depth between lesion at the infarct border (5.9±1.0 mm, n=41) and healthy myocardium (5.7±1.3 mm, n=26; P =0.53). PFA penetration of both infarct and iatrogenic radiofrequency abalation scar was observed in all examined sections. Sustained ventricular arrhythmias requiring defibrillation occurred in 4 of 187 (2.1%) ungated applications, whereas no ventricular arrhythmias occurred during gated PFA applications (0 of 64 [0%]). Dark-blood late-gadolinium-enhanced sequences allowed for improved endocardial border detection as well as lesion boundaries compared with conventional bright-blood late-gadolinium-enhanced sequences., Conclusions: PFA penetrates infarct and iatrogenic scar successfully to create deep lesions. Gated delivery eliminates the occurrence of ventricular arrhythmias observed with ungated porcine PFA. Optimized magnetic resonance imaging sequences can be helpful in detecting lesion boundaries.

Background: Our understanding of catheter-based pulsed field ablation (PFA) of the ventricular myocardium is limited. We conducted a series of exploratory evaluations of ventricular PFA in swine ventricles., Methods: A focal lattice-tip catheter was used to deliver proprietary biphasic monopolar PFA applications to swine ventricles under general anesthesia, with guidance from electroanatomical mapping, fluoroscopy, and intracardiac echocardiography. We conducted experiments to assess the impact of (1) delivery repetition (2×, 3×, or 4×) at each location, (2) epicardial PFA delivery, and (3) confluent areas of shallow healed endocardial scar created by prior PFA (4 weeks earlier) on subsequent endocardial PFA. Additional assessments included PFA optimized for the ventricle, lesion visualization by intracardiac echocardiography imaging, and immunohistochemical insights., Results: Experiment no. 1: lesions (n=49) were larger with delivery repetition of either 4× or 3× versus 2×: length 17.6±3.9 or 14.2±2.0 versus 12.7±2.0 mm ( P <0.01, P =0.22), width 13.4±1.8 or 10.6±1.3 versus 10.5±1.1 mm ( P <0.01, P =1.00), and depth 6.1±2.1 or 5.1±1.3 versus 4.2±1.0 mm ( P <0.01, P =0.21). Experiment no. 2: epicardial lesions (n=18) were reliably created and comparable to endocardial lesions: length 24.6±9.7 mm (n=5), width 15.6±4.6 mm, and depth 4.5±3.7 mm. Experiment no. 3: PFA (n=16) was able to penetrate to a depth of 4.8 (interquartile range, 4.5-5.4) mm in healthy myocardium versus 5.6 (interquartile range, 3.6-6.6) mm in adjacent healed endocardial scar ( P =0.79), suggesting that superficial scar does not significantly impair PFA. Finally, we demonstrate, PFA optimized for the ventricle yielded adequate lesion dimensions, can result in myocardial activation, can be visualized by intracardiac echocardiography, and have unique immunohistochemical characteristics., Conclusions: This in vivo evaluation offers insights into the behavior of endocardial or epicardial PFA delivered using the lattice-tip catheter to normal or scarred porcine ventricular myocardium, thereby setting the stage for future clinical studies.

Background: Frequent premature ventricular contractions (PVCs) are often amenable to catheter ablation. However, a deep intramural focus may lead to failure due to inability of standard ablation techniques to penetrate the focus. We sought to assess the efficacy and safety of infusion needle ablation (INA) for PVCs that are refractory to standard radiofrequency ablation., Methods: Under 2 Food and Drug Administration approved protocols, INA was evaluated in patients with frequent PVCs that were refractory to standard ablation. Initial targets for ablation were selected by standard mapping techniques. INA was performed with a deflectable catheter equipped with an extendable/retractable needle at the tip that can be extended up to 12 mm into the myocardium and is capable of pacing and recording. After contrast injection for location assessment, radiofrequency ablation was performed with the needle tip using a temperature-controlled mode (maximum temperature 60 °C) with saline infusion from the needle. The primary end point was a decrease in PVC burden to <5000/24 hours at 6 months. The primary safety end point was incidence of procedure- or device-related serious adverse events., Results: At 4 centers, 35 patients (age 55.3±16.9 years, 74.2% male) underwent INA. The baseline median PVC burden was 25.4% (interquartile range, 18.4%-33.9%) and mean left ventricular ejection fraction was 37.7±12.3%. Delivering 10.3±8.0 INA lesions/patient (91% had adjunctive standard radiofrequency ablation also) resulted in acute PVC elimination in 71.4%. After a mean follow-up of 156±109 days, the primary efficacy end point was met in 73.3%. The median PVC burden decreased to 0.8% (interquartile range, 0.1%-6.0%; P <0.001). The primary safety end point occurred in 14.3% consisting of 1 (2.9%) heart block, 1 (2.9%) femoral artery dissection, and 3 (8.6%) pericardial effusions (all treated percutaneously)., Conclusions: INA is effective for the elimination of frequent PVCs that are refractory to conventional ablation and is associated with an acceptable safety profile., Registration: URL: https://www., Clinicaltrials: gov; Unique identifier: NCT01791543 and NCT03204981.

Objectives: This study sought to examine the effect of the return electrode's surface area on bipolar RFA lesion size., Background: Bipolar radiofrequency ablation (RFA) is typically performed between 2 3.5-mm tip catheters serving as active and return electrodes. We hypothesized that increasing the surface area of the return electrode would increase lesion dimensions by reducing the circuit impedance, thus increasing the current into a larger tissue volume enclosed between the electrodes., Methods: In step 1, ex vivo bipolar RFA was performed between 3.5-mm and custom-made return electrodes with increasing surface areas (20, 80, 180 mm 2 ). In step 2, ex vivo bipolar RFA was performed between 3.5-mm and 3.5-mm or 8-mm electrode catheters positioned perpendicular or parallel to the tissue. In step 3, in vivo bipolar RFA was performed between 3.5-mm and either 3.5-mm or 8-mm parallel electrode at the: 1) left ventricular summit; 2) interventricular septum; and 3) healed anterior infarction., Results: In step 1, increasing the surface area of the return electrode resulted in lower circuit impedance (R = -0.65; P < 0.001), higher current (R = +0.80; P < 0.001), and larger lesion volume (R = +0.88; P < 0.001). In step 2, an 8-mm return electrode parallel to tissue produced larger and deeper lesions compared with a 3.5-mm return electrode (P = 0.014 and P = 0.02). Similarly, in step 3, compared with a 3.5-mm, bipolar RFA with an 8-mm return electrode produced larger (volume: 1,525 ± 871 mm 3 vs 306 ± 310 mm 3 , respectively; P < 0.001) and more transmural lesions (88% vs 0%; P < 0.001)., Conclusions: Bipolar RFA using an 8-mm return electrode positioned parallel to the tissue produces larger lesions in comparison with a 3.5-mm return electrode., Competing Interests: Funding Support and Author Disclosures Mr Bubar is an employee of Biosense Webster. Dr Tarakji receives consultation fees from AliveCor, Medtronic, Janssen, and Pfizer. Dr Anter has received research grants and speaking honoraria from Biosense Webster, Boston Scientific, Affera Inc, and Itamar Medical; and holds stock options in Affera Inc. Dr Koruth has received research grants from Affera Inc, Farapulse, Cardiofocus, Biosense, Acutus, Kardium; has equity in Affera Inc; and serves as a consultant to Farapulse and Abbott. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2022 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Aims: We studied the extent/area of electrical pulmonary vein isolation (PVI) after either pulsed field ablation (PFA) using a pentaspline catheter or thermal ablation technologies., Methods and Results: In a clinical trial (NCT03714178), paroxysmal atrial fibrillation (PAF) patients underwent PVI with a multi-electrode pentaspline PFA catheter using a biphasic waveform, and after 75 days, detailed voltage maps were created during protocol-specified remapping studies. Comparative voltage mapping data were retrospectively collected from consecutive PAF patients who (i) underwent PVI using thermal energy, (ii) underwent reablation for recurrence, and (iii) had durably isolated PVs. The left and right PV antral isolation areas and non-ablated posterior wall were quantified. There were 20 patients with durable PVI in the PFA cohort, and 39 in the thermal ablation cohort [29 radiofrequency ablation (RFA), 6 cryoballoon, and 4 visually guided laser balloon]. Pulsed field ablation patients were younger with shorter follow-up. Left atrial diameter and ventricular systolic function were preserved in both cohorts. There was no significant difference between the PFA and thermal ablation cohorts in either the left- and right-sided PV isolation areas, or the non-ablated posterior wall area. The right superior PV isolation area was smaller with PFA than RFA, but this disappeared after propensity score matching. Notch-like normal voltage areas were seen at the posterior aspect of the carina in the balloon sub-cohort, but not the PFA or RFA cohorts., Conclusion: Catheter-based PVI with the pentaspline PFA catheter creates chronic PV antral isolation areas as encompassing as thermal energy ablation., (© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Objectives: The goal of this study is to determine the incidence, predictors, and outcomes of atrial fibrillation (AF) or atrial flutter (AFL) in patients hospitalized with coronavirus disease-2019 (COVID-19)., Background: COVID-19 results in increased inflammatory markers previously associated with atrial arrhythmias. However, little is known about their incidence or specificity in COVID-19 or their association with outcomes., Methods: This is a retrospective analysis of 3,970 patients admitted with polymerase chain reaction-positive COVID-19 between February 4 and April 22, 2020, with manual review performed of 1,110. The comparator arm included 1,420 patients with influenza hospitalized between January 1, 2017, and January 1, 2020., Results: Among 3,970 inpatients with COVID-19, the incidence of AF/AFL was 10% (n = 375) and in patients without a history of atrial arrhythmias it was 4% (n = 146). Patients with new-onset AF/AFL were older with increased inflammatory markers including interleukin 6 (93 vs. 68 pg/ml; p < 0.01), and more myocardial injury (troponin-I: 0.2 vs. 0.06 ng/ml; p < 0.01). AF and AFL were associated with increased mortality (46% vs. 26%; p < 0.01). Manual review captured a somewhat higher incidence of AF/AFL (13%, n = 140). Compared to inpatients with COVID-19, patients with influenza (n = 1,420) had similar rates of AF/AFL (12%, n = 163) but lower mortality. The presence of AF/AFL correlated with similarly increased mortality in both COVID-19 (relative risk: 1.77) and influenza (relative risk: 1.78)., Conclusions: AF/AFL occurs in a subset of patients hospitalized with either COVID-19 or influenza and is associated with inflammation and disease severity in both infections. The incidence and associated increase in mortality in both cohorts suggests that AF/AFL is not specific to COVID-19, but is rather a generalized response to the systemic inflammation of severe viral illnesses., Competing Interests: Funding Support and Author Disclosures Dr Koruth has received consulting fees from Abbott Laboratories, CardioFocus, Farapulse, and Vytron US, Inc. Dr Dukkipati has received grant support from Biosense Webster; and has equity with Farapulse and Manual Surgical Sciences, LLC. Dr Halperin has received consulting fees from Boehringer Ingelheim, Johnson & Johnson-Janssen Pharmaceuticals, and Medtronic. Dr Reddy is a consultant with Abbott, Ablacon, Acutus Medical, Affera, Apama Medical, Aquaheart, Atacor, Autonomix, Axon, Backbeat, BioSig, Biosense Webster, Biotronik, Boston Scientific, Cardiofocus, Cardionomic, CardioNXT/AFTx, Circa Scientific, Corvia Medical, Dinova-Hangzhou Nuomao Medtech Co., Ltd., East End Medical, EBR, EPD, Epix Therapeutics, EpiEP, Eximo, Fire1, Impulse Dynamics, Javelin, Kardium, Keystone Heart, LuxCath, Manual Surgical Sciences, Medlumics, Medtronic, Middlepeak, Newpace, Nuvera, Philips, Pulse Biosciences, Sirona Medical, Stimda, Surecor, Thermedical, and Valcare; and has equity in Ablacon, Acutus Medical, Affera, Apama, Aquaheart, Atacor, Autonomix, Backbeat, BioSig, Circa Scientific, Corvia Medical, Dinova-Hangzhou Nuomao Medtech Co., Ltd., East End Medical, EPD, Epix Therapeutics, EpiEP, Eximo, Fire 1, Javelin, Kardium, Keystone Heart, LuxCath, Manual Surgical Sciences, Medlumics, Middlepeak, Newpace, Nuvera, Sirona Medical, Surecor, Valcare, and Vizaramed. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2021 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Patients with coronavirus disease 2019 (COVID-19) who develop cardiac injury are reported to experience higher rates of malignant cardiac arrhythmias. However, little is known about these arrhythmias-their frequency, the underlying mechanisms, and their impact on mortality., Methods: We extracted data from a registry (NCT04358029) regarding consecutive inpatients with confirmed COVID-19 who were receiving continuous telemetric ECG monitoring and had a definitive disposition of hospital discharge or death. Between patients who died versus discharged, we compared a primary composite end point of cardiac arrest from ventricular tachycardia/fibrillation or bradyarrhythmias such as atrioventricular block., Results: Among 800 patients with COVID-19 at Mount Sinai Hospital with definitive dispositions, 140 patients had telemetric monitoring, and either died (52) or were discharged (88). The median (interquartile range) age was 61 years (48-74); 73% men; and ethnicity was White in 34%. Comorbidities included hypertension in 61%, coronary artery disease in 25%, ventricular arrhythmia history in 1.4%, and no significant comorbidities in 16%. Compared with discharged patients, those who died had elevated peak troponin I levels (0.27 versus 0.02 ng/mL) and more primary end point events (17% versus 4%, P =0.01)-a difference driven by tachyarrhythmias. Fatal tachyarrhythmias invariably occurred in the presence of severe metabolic imbalance, while atrioventricular block was largely an independent primary event., Conclusions: Hospitalized patients with COVID-19 who die experience malignant cardiac arrhythmias more often than those surviving to discharge. However, these events represent a minority of cardiovascular deaths, and ventricular tachyarrhythmias are mainly associated with severe metabolic derangement. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04358029.

Background: The tissue selectivity of pulsed field ablation (PFA) provides safety advantages over radiofrequency ablation in treating atrial fibrillation. One-shot PFA catheters have been shown capable of performing pulmonary vein isolation, but not flexible lesion sets such as linear lesions. A novel lattice-tip ablation catheter with a compressible 9-mm nitinol tip is able to deliver either focal radiofrequency ablation or PFA lesions, each in 2 to 5 s., Methods: In a 3-center, single-arm, first-in-human trial, the 7.5F lattice catheter was used with a custom mapping system to treat paroxysmal or persistent atrial fibrillation. Toggling between energy sources, point-by-point pulmonary vein encirclement was performed using biphasic PFA posteriorly and either temperature-controlled irrigated radiofrequency ablation or PFA anteriorly (RF/PF or PF/PF, respectively). Linear lesions were created using either PFA or radiofrequency ablation., Results: The 76-patient cohort included 55 paroxysmal and 21 persistent atrial fibrillation patients undergoing either RF/PF (40 patients) or PF/PF (36 patients) ablation. The pulmonary vein isolation therapy duration time (transpiring from first to last lesion) was 22.6±8.3 min/patient, with a mean of 50.1 RF/PF lesions/patient. Linear lesions included 14 mitral (4 RF/2 RF+PF/8 PF), 34 left atrium roof (12 RF/22 PF), and 44 cavotricuspid isthmus (36 RF/8 PF) lines, with therapy duration times of 5.1±3.5, 1.8±2.3, and 2.4±2.1 min/patient, respectively. All lesion sets were acutely successful, using 4.7±3.5 minutes of fluoroscopy. There were no device-related complications, including no strokes. Postprocedure esophagogastroduodenoscopy revealed minor mucosal thermal injury in 2 of 36 RF/PF and 0 of 24 PF/PF patients. Postprocedure brain magnetic resonance imaging revealed diffusion-weighted imaging+/fluid-attenuated inversion recovery- and diffusion-weighted imaging+/fluid-attenuated inversion recovery+ asymptomatic lesions in 5 and 3 of 51 patients, respectively., Conclusions: A novel lattice-tip catheter could safely and rapidly ablate atrial fibrillation using either a combined RF/PF approach (capitalizing on the safety of PFA and the years of experience with radiofrequency energy) or an entirely PF approach. Registration: URL: https://www.clinicaltrials.gov; Unique identifiers: NCT04141007 and NCT04194307.

Background: A novel ablation and mapping system can toggle between delivering biphasic pulsed field (PF) and radiofrequency energy from a 9-mm lattice-tip catheter. We assessed the preclinical feasibility and safety of (1) focal PF-based thoracic vein isolation and linear ablation, (2) combined PF and radiofrequency focal ablation, and (3) PF delivered directly atop the esophagus., Methods: Two cohorts of 6 swine were treated with pulsed fields at low dose (PF LD ) and high dose (PF HD ) and followed for 4 and 2 weeks, respectively, to isolate 25 thoracic veins and create 5 right atrial (PF LD ), 6 mitral (PF HD ), and 6 roof lines (radiofrequency+PF HD ). Baseline and follow-up voltage mapping, venous potentials, ostial diameters, and phrenic nerve viability were assessed. PF HD and radiofrequency lesions were delivered in 4 and 1 swine from the inferior vena cava onto a forcefully deviated esophagus. All tissues were submitted for histopathology., Results: Hundred percent of thoracic veins (25 of 25) were successfully isolated with 12.4±3.6 applications/vein with mean PF times of <90 seconds/vein. Durable isolation improved from 61.5% PF LD to 100% with PF HD ( P =0.04), and all linear lesions were successfully completed without incurring venous stenoses or phrenic injury. PF HD sections had higher transmurality rates than PF LD (98.3% versus 88.1%; P =0.03) despite greater mean thickness (2.5 versus 1.3 mm; P <0.001). PF lesions demonstrated homogenous fibrosis without epicardial fat, nerve, or vessel involvement. In comparison, radiofrequency+PF HD sections revealed similar transmurality but expectedly more necrosis, inflammation, and epicardial fat, nerve, and vessel involvement. Significant ablation-related esophageal necrosis, inflammation, and fibrosis were seen in all radiofrequency sections, as compared with no PF sections., Conclusions: The lattice-tip catheter can deliver focal PF to durably isolate veins and create linear lesions with excellent transmurality and without complications. The PF lesions did not damage the phrenic nerve, vessels, and the esophagus.

Aims: Pulsed field ablation (PFA) is a novel, non-thermal modality that selectively ablates myocardium with ultra-short electrical impulses while sparing collateral tissues. In a proof-of-concept study, the safety and feasibility of ventricular PFA were assessed using a prototype steerable, endocardial catheter., Methods and Results: Under general anaesthesia, the left and right ventricles of four healthy swine were ablated using the 12-Fr deflectable PFA catheter and a deflectable sheath guided by electroanatomic mapping. Using the study catheter, electrograms were recorded for each site and pre-ablation and post-ablation pacing thresholds (at 2.0 ms pulse width) were recorded in two of four animals. After euthanasia at 35.5 days, the hearts were submitted for histology. The PFA applications (n = 39) resulted in significant electrogram reduction without ventricular arrhythmias. In ablation sites where it was measured, the pacing thresholds increased by >16.8 mA in the right ventricle (3 sites) and >16.1 mA in the left ventricle (7 sites), with non-capture at maximum amplitude (20 mA) observable in 8 of 10 sites. Gross measurements, available for 28 of 30 ablation sites, revealed average lesion dimensions to be 6.5 ± 1.7 mm deep by 22.6 ± 4.1 mm wide, with a maximum depth and width of 9.4 mm and 28.6 mm, respectively. In the PFA lesions, fibrous tissue homogeneously replaced myocytes with a narrow zone of surrounding myocytolysis and no overlying thrombus. When present, nerve fascicles and vasculature were preserved within surrounding fibrosis., Conclusion: We demonstrate that endocardial PFA can be focally delivered using this prototype catheter to create homogeneous, myocardium-specific lesions., (© The Author(s) 2019. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Pulsed field ablation (PFA) can be myocardium selective, potentially sparing the esophagus during left atrial ablation. In an in vivo porcine esophageal injury model, we compared the effects of newer biphasic PFA with radiofrequency ablation (RFA)., Methods: In 10 animals, under general anesthesia, the lower esophagus was deflected toward the inferior vena cava using an esophageal deviation balloon, and ablation was performed from within the inferior vena cava at areas of esophageal contact. Four discrete esophageal sites were targeted in each animal: 6 animals received 8 PFA applications/site (2 kV, multispline catheter), and 4 animals received 6 clusters of irrigated RFA applications (30 W×30 seconds, 3.5 mm catheter). All animals were survived to 25 days, sacrificed, and the esophagus submitted for pathological examination, including 10 discrete histological sections/esophagus., Results: The animals weight increased by 13.7±6.2% and 6.8±6.3% ( P =0.343) in the PFA and RFA cohorts, respectively. No PFA animals (0 of 6, 0%) developed abnormal in-life observations, but 1 of 4 RFA animals (25%) developed fever and dyspnea. On necropsy, no PFA animals (0 of 6, 0%) demonstrated esophageal lesions. In contrast, esophageal injury occurred in all RFA animals (4 of 4, 100%; P =0.005): a mean of 1.5 mucosal lesions/animal (length, -21.8±8.9 mm; width, -4.9±1.4 mm) were observed, including one esophago-pulmonary fistula and deep esophageal ulcers in the other animals. Histological examination demonstrated tissue necrosis surrounded by acute and chronic inflammation and fibrosis. The necrotic RFA lesions involved multiple esophageal tissue layers with evidence of arteriolar medial thickening and fibrosis of periesophageal nerves. Abscess formation and full-thickness esophageal wall disruptions were seen in areas of perforation/fistula., Conclusions: In this novel porcine model of esophageal injury, biphasic PFA induced no chronic histopathologic esophageal changes, while RFA demonstrated a spectrum of esophageal lesions including fistula and deep esophageal ulcers and abscesses.

Aims: During atrial fibrillation ablation, oesophageal heating typically prompts reduction or termination of radiofrequency energy delivery. We previously demonstrated oesophageal temperature rises are associated with posterior left atrial pulmonary vein reconnection (PVR) during redo procedures. In this study, we assessed whether mechanical oesophageal deviation (MED) during an index procedure minimizes posterior wall PVRs during redo procedures., Methods and Results: Patients in whom we performed a first-ever procedure followed by a clinically driven redo procedure were divided based on both the use of MED for oesophageal protection and the ablation catheter employed (force or non-force sensing) in the first procedure. The PVR sites were compared between MED using a force-sensing catheter (MEDForce), or no MED with a non-force (ControlNoForce) or force (ControlForce) sensing catheter. Despite similar clinical characteristics, the MEDForce redo procedure rate (9.2%, 26/282 patients) was significantly less than the ControlNoForce (17.2%, 126/734 patients; P = 0.002) and ControlForce (17.5%, 20/114 patients; P = 0.024) groups. During the redo procedure, the posterior PVR rate with MEDForce (2%, 1/50 PV pairs) was significantly less than with either ControlNoForce (17.7%, 44/249 PV pairs; P = 0.004) or ControlForce (22.5%, 9/40 PV pairs; P = 0.003), or aggregate Controls (18.3%, 53/289 PV pairs; P = 0.006). However, the anterior PVR rate with MEDForce (8%, 4/50 PV pairs) was not significantly different than Controls (aggregate Controls-3.5%, 10/289 PV pairs, P = 0.136; ControlNoForce-2.4%, 6/249 PV pairs, P = 0.067; ControlForce-10%, 4/40 PV pairs, P = 1.0)., Conclusion: Oesophageal deviation improves the durability of the posterior wall ablation lesion set during AF ablation., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Background: Nodofascicular and nodoventricular (NFV) accessory pathways connect the atrioventricular node and the Purkinje system or ventricular myocardium, respectively. Concealed NFV pathways participate as the retrograde limb of supraventricular tachycardia (SVT). Manifest NFV pathways can comprise the anterograde limb of wide-complex SVT but are quite rare. The purpose of this report is to highlight the electrophysiological properties and sites of ablation for manifest NFV pathways., Methods: Eight patients underwent electrophysiology studies for wide-complex tachycardia (3), for narrow-complex tachycardia (1), and preexcitation (4)., Results: NFV was an integral part of the SVT circuit in 3 patients. Cases 1 to 2 were wide-complex tachycardia because of manifest NFV SVT. Case 3 was a bidirectional NFV that conducted retrograde during concealed NFV SVT and anterograde causing preexcitation during atrial pacing. NFV was a bystander during atrioventricular node re-entrant tachycardia, atrial fibrillation, atrial flutter, and orthodromic atrioventricular re-entrant tachycardia in 4 cases and caused only preexcitation in 1. Successful NFV ablation was achieved empirically in the slow pathway region in 1 case. In 5 cases, the ventricular insertion was mapped to the slow pathway region (2 cases) or septal right ventricle (3 cases). The NFV was not mapped in cases 5 and 7 because of its bystander role. QRS morphology of preexcitation predicted the right ventricle insertion sites in 4 of the 5 cases in which it was mapped. During follow-up, 1 patient noted recurrent palpitations but no documented SVT., Conclusions: Manifest NFV may be critical for wide-complex tachycardia/manifest NFV SVT, act as the retrograde limb for narrow-complex tachycardia/concealed NFV SVT, or cause bystander preexcitation. Ablation should initially target the slow pathway region, with mapping of the right ventricle insertion site if slow pathway ablation is not successful. The QRS morphology of maximal preexcitation may be helpful in predicting successful right ventricle ablation site.

Background: Catheter ablation of atrial fibrillation using thermal energies such as radiofrequency or cryothermy is associated with indiscriminate tissue destruction. During pulsed field ablation (PFA), subsecond electric fields create microscopic pores in cell membranes-a process called electroporation. Among cell types, cardiomyocytes have among the lowest thresholds to these fields, potentially permitting preferential myocardial ablation., Objectives: The purpose of these 2 trials was to determine whether PFA allows durable pulmonary vein (PV) isolation without damage to collateral structures., Methods: Two trials were conducted to assess the safety and effectiveness of catheter-based PFA in paroxysmal atrial fibrillation. Ablation was performed using proprietary bipolar PFA waveforms: either monophasic with general anesthesia and paralytics to minimize muscle contraction, or biphasic with sedation because there was minimal muscular stimulation. No esophageal protection strategy was used. Invasive electrophysiological mapping was repeated after 3 months to assess the durability of PV isolation., Results: In 81 patients, all PVs were acutely isolated by monophasic (n = 15) or biphasic (n = 66) PFA with ≤3 min elapsed delivery/patient, skin-to-skin procedure time of 92.2 ± 27.4 min, and fluoroscopy time of 13.1 ± 7.6 min. With successive waveform refinement, durability at 3 months improved from 18% to 100% of patients with all PVs isolated. Beyond 1 procedure-related pericardial tamponade, there were no additional primary adverse events over the 120-day median follow-up, including: stroke, phrenic nerve injury, PV stenosis, and esophageal injury. The 12-month Kaplan-Meier estimate of freedom from arrhythmia was 87.4 ± 5.6%., Conclusions: In first-in-human trials, PFA preferentially affected myocardial tissue, allowing facile ultra-rapid PV isolation with excellent durability and chronic safety. (IMPULSE: A Safety and Feasibility Study of the IOWA Approach Endocardial Ablation System to Treat Atrial Fibrillation; NCT03700385; and PEFCAT: A Safety and Feasibility Study of the FARAPULSE Endocardial Ablation System to Treat Paroxysmal Atrial Fibrillation; NCT03714178)., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Compared with warfarin, left atrial appendage closure (LAAC) reduced mortality in an analysis of the PROTECTAF and PREVAIL trials. However, these data were limited by patient drop-out.We sought to estimatethe mortality benefit with LAACusing updated vital status information.In PROTECT AF and PREVAIL, 227 of 1114 randomized subjects failed to complete 5-year follow-up. Centers were manually queried for updated vital status on 76 subjects (33%).During median follow-up 5.0 years (interquartile range 3.8, 5.1), 112 of 732 LAAC subjects (15.3%) and 79 of 382 controls (20.7%) died. The hazard ratio for all-cause mortality with LAAC compared with warfarin was 0.70 (95% CI 0.53-0.94, p=0.017).Subgroup analyses suggested that subjects <75 years and those with higher CHA2DS2-VASc score, history of transient ischemic attack or stroke, and permanent AF derived particular benefit, although interaction terms were not significant.The number needed to treat(NNT) with LAAC to prevent one death over 5 years was 16 (95% CI 10-82). Despite competing mortality risks in this elderly cohort, updated vital status data from PROTECT AF and PREVAIL revealed that LAAC was associated with 30% improved survival compared with warfarin, with an NNT of 16.

Objectives: The goal of this study was to determine the safety and feasibility of a novel esophageal balloon retractor (DV8) for MED during PVI., Background: The authors previously showed that mechanical esophageal deviation (MED) is feasible using an off-the-shelf metal stylet to allow uninterrupted ablation along the posterior left atrium during pulmonary vein isolation (PVI). Although it is an attractive strategy to avoid esophageal thermal injury, this technique was hampered by both the propensity for oropharyngeal trauma from the stiff stylet and the limited lateral esophageal displacement., Methods: In 200 consecutive patients undergoing atrial fibrillation ablation, the DV8 balloon retractor was used for MED; contrast was instilled into the esophagus to accurately delineate the trailing esophageal edge. Deviation was performed to maximize the distance from the trailing esophageal edge to the closest point of the ablation line (MED Effective ) and correlated to occurrences of luminal esophageal temperature elevation., Results: In patients undergoing MED during a first-ever PVI of 304 vein pairs, the MED Effective during right and left PVI were 21.2 ± 8.7 mm and 15.5 ± 6.8 mm, respectively. Deviation of at least 5 mm of MED Effective was achievable in 97.7%. Luminal esophageal temperature increases universally occurred (100%) at MED Effective  <5 mm, less often (28%) at MED Effective 5 to 20 mm, and rarely (1.9%) at MED Effective >20 mm. There were no esophageal complications, but 2 patients experienced oropharyngeal bleeding due to trauma related to device placement., Conclusions: MED with the balloon retractor safely moved the esophagus away from the site of energy delivery during atrial fibrillation ablation., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

In contrast to ventricular tachycardia (VT) that occurs in the setting of a structurally normal heart, VT that occurs in patients with structural heart disease carries an elevated risk for sudden cardiac death (SCD), and implantable cardioverter-defibrillators (ICDs) are the mainstay of therapy. In these individuals, catheter ablation may be used as adjunctive therapy to treat or prevent repetitive ICD therapies when antiarrhythmic drugs are ineffective or not desired. However, certain patients with frequent premature ventricular contractions (PVCs) or VT and tachycardiomyopathy should be considered for ablation before ICD implantation because left ventricular function may improve, consequently decreasing the risk of SCD and obviating the need for an ICD. The goal of this paper is to review the pathophysiology, mechanism, and management of VT in the setting of structural heart disease and discuss the evolving role of catheter ablation in decreasing ventricular arrhythmia recurrence., (Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Catheter ablation of ventricular tachycardia (VT) is being increasingly performed; yet, there is often confusion regarding indications, outcomes, and how to identify those patient populations most likely to benefit. The management strategy differs between those with structural heart disease and those without. For the former, an implantable cardioverter-defibrillator (ICD) is typically required due to an elevated risk for sudden cardiac death, and catheter ablation can be used as adjunctive therapy to treat or prevent repetitive ICD therapies. In contrast, VT or premature ventricular contractions in the setting of a structurally normal heart carries a low risk for sudden cardiac death; accordingly, there is typically no indication for an ICD. In these patients, catheter ablation is considered for symptom management or to treat tachycardiomyopathy and is potentially curative. Here, the authors discuss the pathophysiology, mechanism, and management of VT that occurs in the setting of a structurally normal heart and the role of catheter ablation., (Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

The clinical use of ivabradine has and continues to evolve along channels that are predicated on its mechanism of action. It selectively inhibits the funny current (I f ) in sinoatrial nodal tissue, resulting in a decrease in the rate of diastolic depolarization and, consequently, the heart rate, a mechanism that is distinct from those of other negative chronotropic agents. Thus, it has been evaluated and is used in select patients with systolic heart failure and chronic stable angina without clinically significant adverse effects. Although not approved for other indications, ivabradine has also shown promise in the management of inappropriate sinus tachycardia. Here, the authors review the mechanism of action of ivabradine and salient studies that have led to its current clinical indications and use., (Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: This study sought to compare a novel lesion dimension estimation approach to actual measurements of lesion dimensions on necropsy in porcine atria and ventricles., Background: An irrigated-tip, force-sensing radiofrequency catheter with 6 temperature (tip-tissue interface) sensors allows for assessment of lesion dimensions based on estimated tissue temperature. Lesion dimension assessment has not been attempted previously in atrial tissue., Methods: Ablations were performed using this catheter in all chambers. Irrigated radiofrequency was delivered using 20 to 50 W for durations that ranged from 15 to 90 s with contact force ranging from 5 to 45 g to replicate a wide spectrum of clinical conditions. All swine were then sacrificed and lesions were identified and photographed. Three independent observers made offline measurements, which were then averaged to obtain lesion width and depth for comparison with estimated dimensions based on interface tissue temperature., Results: In 9 swine, 54 atrial and 61 ventricular lesions were assessed. In the atria, the mean difference between the measured and estimated depth and width was 0.9 ± 0.74 mm and 1.2 ± 0.9 mm, respectively. Eighty percent of all lesions had a difference of ≤1.7 mm for depth and ≤1.74 mm for width. In the ventricle, the mean difference between the measured and estimated depth and width was 0.75 ± 0.6 mm and 1.66 ± 1.1 mm, respectively. Eighty percent of all lesions had a difference of ≤1.1 mm ventricular depth and ≤2.6 mm for width., Conclusions: Estimation of lesion dimensions can be achieved with clinically relevant accuracy using unique temperature signatures. These data have important implications for understanding the adequacy of lesion overlap and assessment of transmurality., (Copyright © 2017. Published by Elsevier Inc.)

Objectives: This study sought to determine the extent of lateral esophageal displacement required during mechanical esophageal deviation (MED) and to eliminate luminal esophageal temperature elevation (LET Elev ) during pulmonary vein (PV) isolation., Background: MED is a conceptually attractive strategy of minimizing esophageal injury while allowing uninterrupted energy delivery along the posterior left atrium during PV isolation., Methods: MED was performed using a malleable metal stylet within a plastic tube placed within the esophagus. Barium was instilled to characterize the trailing esophageal edge. For each MED attempt, the MED Effective , defined as the distance from the trailing esophageal edge-to-ablation line, was correlated to occurrences of LET Elev ., Results: In 114 consecutive patients/221 PV pairs undergoing MED (age 62.1 ± 11 years, 75% men, 62%/38% paroxysmal/persistent AF), esophageal stretching invariably occurred such that the esophageal edge trailed behind the plastic tube. MED Effective distances of 0 mm to 10 mm, 10 mm to 15 mm, 15 mm to 20 mm or >20 mm were achieved in 60 (27.1%), 64 (29%), 48 (21.7%), and 49 (22.2%) attempts, respectively. Overall, LET elevation >38°C occurred in 81 of 221 (36.7%) PV pairs. The incidence of LET Elev among the 4 groups was 73.3%, 35.9%, 25%, and 4.1%, respectively. MED Effective distances were 9.1 ± 6.5 mm and 18 ± 7.6 mm in patients with and without LET Elev , respectively (p < 0.0001). Three patients (2.6%) experienced clinically significant MED-related trauma, albeit only with a stiffer stylet., Conclusions: Mechanical esophageal deviation >20 mm from the PV ablation line prevents significant esophageal heating during PV isolation, but this level of displacement was difficult to safely achieve with this off-the-shelf mechanical stylet approach., (Copyright © 2017. Published by Elsevier Inc.)

Background: Saline irrigation improved the safety of radiofrequency (RF) ablation, but the thermal feedback for energy titration is absent., Objectives: To allow temperature-controlled irrigated ablation, a novel irrigated RF catheter was designed with a diamond-embedded tip (for rapid cooling) and 6 surface thermocouples to reflect tissue temperature. High-resolution electrograms (EGMs) from the split-tip electrode allowed rapid lesion assessment. The authors evaluated the preclinical and clinical performance of this catheter for pulmonary vein (PV) isolation., Methods: Using the DiamondTemp (DT) catheter, pigs (n = 6) underwent discrete atrial ablation in a temperature control mode (60°C/50 W) until there was ∼80% EGM amplitude reduction. In a single-center clinical feasibility study, 35 patients underwent PV isolation with the DT catheter (study group); patients were planned for PV remapping after 3 months, regardless of symptomatology. A control group included 35 patients who underwent PV isolation with a standard force-sensing catheter., Results: Porcine lesion histology revealed transmurality in 51 of 55 lesions (92.7%). In patients, all PVs were successfully isolated; no char or thrombus formation was observed. Compared with the control group, the study cohort had shorter mean RF application duration (26.3 ± 5.2 min vs. 89.2 ± 27.2 min; p < 0.001), shorter mean fluoroscopic time (11.2 ± 8.5 min vs. 19.5 ± 6.8 min; p < 0.001), and lower acute dormant PV reconduction (0 of 35 vs. 5 of 35; p = 0.024). At 3 months, 23 patients underwent remapping: 39 of 46 PV pairs (84.8%) remained durably isolated in 17 of these patients (73.9%)., Conclusions: This first-in-human series demonstrated that temperature-controlled irrigated ablation produced rapid, efficient, and durable PV isolation. (ACT DiamondTemp Temperature-Controlled and Contact Sensing RF Ablation Clinical Trial for Atrial Fibrillation [TRAC-AF]; NCT02821351)., (Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Although percutaneous left ventricular assist devices (pLVADs) facilitate mapping and ablation of hemodynamically unstable ventricular tachycardia (VT), there is limited data whether clinical outcomes are improved. We sought to retrospectively compare the outcomes of patients undergoing scar-related VT ablation with and without pLVAD support., Methods and Results: The study population comprised 194 patients (109 pLVAD and 85 non-pLVAD). The pLVAD group more often had dilated cardiomyopathy (33% versus 13%; P =0.001), New York Heart Association heart failure class ≥III (51% versus 25%; P <0.001), lower left ventricular ejection fractions (26±10% versus 39±16%; P <0.001), and electrical storm (49% versus 34%; P =0.04). Procedure times (422±112 versus 330±92 minutes; P <0.001), postablation VT inducibility (20% versus 7%; P =0.02), and length of subsequent hospitalization (median 6 versus 4 days; P =0.001) were all higher in the pLVAD group. During median follow-up of 215 days, the primary end point (recurrent VT, heart transplantation, or death) occurred in 36% of the pLVAD versus 26% of the non-pLVAD groups ( P =0.14). After propensity matching for differences between groups, no differences were seen between groups for both acute procedural outcomes and the primary end point., Conclusions: In this large single-center scar-related VT ablation experience, despite the worse clinical status of the patients selected for pLVAD support, clinical outcomes were better than expected and were similar to healthier patients not receiving hemodynamic support. Patients with dilated cardiomyopathy presenting with electrical storm, advanced heart failure, and severe left ventricular dysfunction most frequently received hemodynamic support during VT ablation., (© 2017 American Heart Association, Inc.)

Objectives: This in vivo ovine study describes the feasibility and safety of retrieving implanted leadless pacemakers (LPs)., Background: Although LPs have been shown to be removable soon after implantation, there are no data on the feasibility of removing chronically implanted LPs., Methods: This study was performed in 2 phases. In the mid-term cohort, 10 chronically (5.3 months) implanted animals underwent retrieval, followed by: 1) immediate necropsy in 5; and 2) in the remaining 5, reimplantation of a new LP followed by necropsy at 6 weeks. In the long-term cohort, 8 additional sheep underwent retrieval at 2.3 ± 0.1 years followed by necropsy. Retrieval was performed using either a single or triple loop snare. All 18 LPs (100%) were successfully retrieved. The time from retrieval catheter insertion to retrieval was 2:35 ± 01:11 and 3:04 ± 01:13 minutes in the mid-term and long-term study groups, respectively., Results: There were no significant differences in retrieval times using either snare. Intracardiac echocardiography was used pre- and post-retrieval to confirm the absence of pericardial effusion in all 8 sheep. On necropsy, there was no evidence of pericardial bleeding or perforation. Only minor tissue disruption and hemorrhage was noted at the implant site after retrieval. Histology demonstrated fibrous connective tissue at the contact sites of endocardium and LP can and at the helix. There was no evidence of pulmonary thromboembolism., Conclusions: We demonstrate the feasibility and safety of percutaneous, catheter-based retrieval in chronic LP implants of a maximum duration of approximately 2.5 years., (Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Catheter ablation of atrial ablation (AF) has become an important therapy in recent years. As with all evolving techniques, unexpected complication may occur. Atrioesophageal fistula is a very rare complication of AF catheter ablation. Described for the first time in two very experienced centers in 2004, this complication is the most dreadful and lethal among all the others related to AF catheter ablation. Its clinical presentation is extremely variable. Rapid diagnosis and surgical therapy may prevent death. This review article will summarize the risk factors, diagnosis, treatment and possible preventive strategies for this condition.