First-in-human clinical series of a novel conformable large-lattice pulsed field ablation catheter for pulmonary vein isolation

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.

Coronary Artery Spasm During Pulsed Field vs Radiofrequency Catheter Ablation of the Mitral Isthmus

Importance

In treating atrial fibrillation, pulsed field ablation (PFA) is a novel energy modality with comparable efficacy to conventional thermal ablation, such as radiofrequency ablation (RFA), but with the benefit of some preferentiality to myocardial tissue ablation. Studies have demonstrated important safety advantages, including the absence of esophageal injury or pulmonary vein stenosis and only rare phrenic nerve injury. However, there is emerging evidence of coronary artery vasospasm provoked by PFA.

Objective

To compare the incidence and severity of left circumflex arterial vasospasm between PFA and RFA during adjacent ablation along the mitral isthmus.

Design, Setting, and Participants

This prospective cohort study enrolled consecutive adult patients receiving first-ever PFA or RFA of the mitral isthmus during catheter ablation of atrial fibrillation in 2022 with acute follow-up at a single referral European center.

Exposure

A posterolateral mitral isthmus line was created using either a multielectrode pentaspline PFA catheter (endocardial ablation) or a saline-irrigated RFA catheter. Simultaneous diagnostic coronary angiography was performed before, during, and after catheter ablation. Nitroglycerin was planned for spasm persisting beyond 20 minutes or for significant electrocardiographic changes.

Main Outcomes and Measures

The frequency and severity of left circumflex arterial vasospasm was assessed and monitored, as were time to remission and any need for nitroglycerin administration.

Results

Of 26 included patients, 19 (73%) were male, and the mean (SD) age was 65.5 (9.3) years. Patients underwent either PFA (n = 17) or RFA (n = 9) along the mitral isthmus. Coronary spasm was observed in 7 of 17 patients (41.2%) undergoing PFA: in 7 of 9 (77.8%) when the mitral isthmus ablation line was situated superiorly and in 0 of 8 when situated inferiorly. Conversely, coronary spasm did not occur in any of the 9 patients undergoing RFA. Of 5 patients in whom crossover PFA was performed after RFA failed to achieve conduction block, coronary spasm occurred in 3 (60%). Most instances of spasm (9 of 10 [90%]) were subclinical, with 2 (20%) requiring nitroglycerin administration. The median (range) time to resolution of spasm was 5 (5-25) minutes.

Conclusion and Relevance

When creating a mitral isthmus ablation line during catheter ablation of atrial fibrillation, adjacent left circumflex arterial vasospasm frequently occurred with PFA and not RFA but was typically subclinical.

ECG characteristics of "true" left bundle branch block: Insights from transcatheter aortic valve-related LBBB and His-Purkinje conduction system pacing-correctable LBBB

BACKGROUND

Left bundle branch block (LBBB) pattern on the electrocardiogram includes patients with both complete conduction block in the His-Purkinje system as well as nonspecific left ventricular conduction delay without discrete block.

OBJECTIVE

The purpose of this study was to characterize electrocardiographic morphological features of LBBB patterns in patients with (1) LBBB after transcatheter aortic valve replacement (TAVR) and (2) LBBB correctable by conduction system pacing (CSP).

METHODS

Consecutive patients with post-TAVR (n = 123) or CSP-correctable LBBB (n = 58) from 2 centers were included in this retrospective evaluation. QRS durations as well as detailed morphological features, including notching and slurring, of QRS complexes in leads I, aVL, V1, V2, V5, and V6 and in all 3 inferior leads were recorded.

RESULTS

The mean age of the entire cohort was 78.3 ± 10.1 years, with 48% of the cohort being male (87/181). In the CSP-correctable group (n = 58), 14 (24.1%) underwent His-bundle pacing and 44 (75.9%) left bundle branch area pacing. A total of 17 of 181 (9.4%) of the combined cohort failed to completely meet the Strauss criteria. QRS morphology in lead V1/V2 was always either rS or QS, and there were no q/Q waves noted in lead V5/V6. Although dominant R waves were seen in leads I and aVL of 176 of 181 (97.2%), q/Q waves were present in only 21 of 181 (11.6%). Importantly, notched or slurred QRS complexes were identified in at least 1 lead of 4 leads I, aVL, V5, and V6 in 181 of 181 (100%).

CONCLUSION

Strauss criteria and QRS notching are highly prevalent in LBBB after TAVR and in LBBB correctable by CSP.

Reversible Pulsed Electrical Fields as an In Vivo Tool to Study Cardiac Electrophysiology: The Advent of Pulsed Field Mapping

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 (PFREV) could transiently suppress electrical conduction, thereby providing a means to dissect tachycardia circuits in vivo.

METHODS

PFREV 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 PFREV to the atrioventricular node: 17 low-dose (PFREV-LOW) and 10 high-dose (PFREV-HIGH) applications. Finally, in 3 patients manifesting spontaneous tachycardias, PFREV was applied at putative critical sites.

RESULTS

In animals, the immediate post-PFREV 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. PFREV-LOW at the atrioventricular node resulted in transient PR prolongation and transient AV block in 59% and 6%, while PFREV-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. PFREV 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.

Worldwide Experience With an Irrigated Needle Catheter for Ablation of Refractory Ventricular Arrhythmias: Final Report

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).

A Focal Ablation Catheter Toggling Between Radiofrequency and Pulsed Field Energy to Treat Atrial Fibrillation

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).

SGLT2 inhibitors reduce sudden cardiac death risk in heart failure: Meta-analysis of randomized clinical trials

INTRODUCTION

Multiple randomized controlled trials have demonstrated sodium-glucose cotransporter-2 inhibitors (SGLT2i) decrease the composite endpoint of cardiovascular death or heart failure hospitalizations in all heart failure patients. It is uncertain whether SGLT2i impacts the risk of sudden cardiac death in patients with heart failure.

METHODS

A comprehensive search was performed to identify relevant data published before August 28, 2022. Trials were included if: (1) all patients had clinical heart failure (2) SGLT2i and placebo were compared (3) all patients received conventional medical therapy and (4) reported outcomes of interest (sudden cardiac death [SCD], ventricular arrhythmias, atrial arrhythmias).

RESULTS

SCD was reported in seven of the eleven trials meeting selection criteria: 10 796 patients received SGLT2i and 10 796 received placebo. SGLT2i therapy was associated with a significant reduction in the risk of SCD (risk ratios [RR]: 0.68; 95% confidence intervals [CI]: 0.48-0.95; p = .03; I2  = 0%). Absent dedicated rhythm monitoring, there were no significant differences in the incidence of sustained ventricular arrhythmias not associated with SCD (RR: 1.03; 95% CI: 0.83-1.29; p = .77; I2  = 0%) or atrial arrhythmias (RR: 0.91; 95% CI: 0.77-1.09; p = .31; I2  = 29%) between patients receiving an SGLT2i versus placebo.

CONCLUSION

SGLT2i therapy is associated with a reduced risk of SCD in patients with heart failure receiving contemporary medical therapy. Prospective trials are needed to determine the long-term impact of SGLT2i therapy on atrial and ventricular arrhythmias.

Electrophysiology, Pathology, and Imaging of Pulsed Field Ablation of Scarred and Healthy Ventricles in Swine

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.

Pulsed Field Ablation of the Porcine Ventricle Using a Focal Lattice-Tip Catheter

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.

The Mini Electrode-equipped Catheter: Utility for Paroxysmal Supraventricular Tachycardia Ablation

The role of catheter ablation for paroxysmal supraventricular arrhythmias (PSVT) is well established given that it is often a simple, safe, and successful procedure. This article is protected by copyright. All rights reserved.

Intramural Needle Ablation for Refractory Premature Ventricular Contractions

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.

Increasing Lesion Dimensions of Bipolar Ablation by Modulating the Surface Area of the Return Electrode

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 mm²). 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 mm³ vs 306 ± 310 mm³, 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.

A single-center experience with early adoption of physiologic pacing approaches

BACKGROUND

Increasing interest in physiological pacing has been countered with challenges such as accurate lead deployment and increasing pacing thresholds with His-bundle pacing (HBP). More recently, left bundle branch area pacing (LBBAP) has emerged as an alternative approach to physiologic pacing.

OBJECTIVE

To compare procedural outcomes and pacing parameters at follow-up during initial adoption of HBP and LBBAP at a single center.

METHODS

Retrospective review, from September 2016 to January 2020, identified the first 50 patients each who underwent successful HBP or LBBAP. Pacing parameters were then assessed at first follow-up after implantation and after approximately 1 year, evaluating for acceptable pacing parameters defined as sensing R-wave amplitude >5 mV, threshold <2.5 V @ 0.5 ms, and impedance between 400 and 1200 Ω.

RESULTS

The HBP group was younger with lower ejection fraction compared to LBBAP (73.2 ± 15.3 vs. 78.2 ± 9.2 years, p = .047; 51.0 ± 15.9% vs. 57.0 ± 13.1%, p = .044). Post-procedural QRS widths were similarly narrow (119.8 ± 21.2 vs. 116.7 ± 15.2 ms; p = .443) in both groups. Significantly fewer patients with HBP met the outcome for acceptable pacing parameters at initial follow-up (56.0% vs. 96.4%, p = .001) and most recent follow-up (60.7% vs. 94.9%, p ≤ .001; at 399 ± 259 vs. 228 ± 124 days, p ≤ .001). More HBP patients required lead revision due to early battery depletion or concern for pacing failure (0% vs. 13.3%, at a mean of 664 days).

CONCLUSION

During initial adoption, HBP is associated with a significantly higher frequency of unacceptable pacing parameters, energy consumption, and lead revisions compared with LBBAP.

Endocardial ventricular pulsed field ablation: a proof-of-concept preclinical evaluation

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 impact of mechanical oesophageal deviation on posterior wall pulmonary vein reconnection

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.

How does the level of pulmonary venous isolation compare between pulsed field ablation and thermal energy ablation (radiofrequency, cryo, or laser)?

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.