Pulsed-field ablation for the treatment of left atrial reentry tachycardia

Extrapulmonary Vein Areas with Pulsed Field Ablation: Is the Transition Completed?

Pulsed field ablation (PFA) is an innovative technology for the ablation of atrial fibrillation (AF), characterized by its ability to create tissue-selective lesions while minimizing collateral damage to surrounding structures. Isolation of the pulmonary veins (PVs) remains the cornerstone of AF ablation; however, recent evidence underscores the significance of extra-PV triggers, such as those from the posterior wall of the left atrium, the superior vena cava, the coronary sinus, and the left atrial appendage. While preliminary data suggest that PFA may enhance safety outcomes compared to traditional thermal techniques, further studies needed to validate its efficacy in non-PV areas.

Left atrial substrate modification in addition to pulmonary vein isolation using a novel circular variable loop pulsed field ablation catheter

Background

Pulsed field ablation (PFA) is a recently developed technology that causes tissue necrosis through electroporation and has been employed and validated for pulmonary vein isolation (PVI) in atrial fibrillation (AF) ablation. Only few devices have received a CE mark for this use and the VaripulseTM catheter (VaripulseTM, Biosense Webster, Irvine, USA), a variable loop PFA catheter, has been recently approved. Despite the growing experience with PVI, evidence is lacking about the use of PFA catheters and linear ablation lesions, which could potentially be performed with PFA catheters, reducing procedure related costs and time.

Case summary

A 73-year-old Caucasian woman with multiple cardiovascular risk factors presented with highly symptomatic paroxysmal AF and was scheduled to undergo PFA AF ablation using the new Varipulse catheter. The procedure was performed under deep sedation and the catheters were advanced through trans-septal puncture. 3D electroanatomic mapping of the left atrium showed significant anterior wall fibrosis. After PVI, substrate modification through an anterior mitral line (AML) approach was pursued. The AML was performed with additional PFA applications and successful bidirectional block was confirmed by pacing maneuvers without any procedural complications. The patient was discharged the following day, asymptomatic and in a state of well-being.

Conclusion

Individual LA substrate modification, including linear lesion sets, can be delivered in addition to PVI using the novel Varipulse PFA catheter in patients with AF.

Pulsed field ablation for atrial fibrillation

INTRODUCTION

Atrial fibrillation is the most common sustained arrhythmia, associated with substantial morbidity and a reduced quality of life. The current standard of care, transcatheter pulmonary vein isolation using thermal ablation techniques, provides symptom relief but carries a risk of collateral tissue damage. In recent years, pulsed field ablation, a nonthermal technique based on irreversible electroporation, has emerged as a promising alternative to conventional thermal ablation methods.

AREAS COVERED

This review provides an overview of pulsed field ablation, a novel nonthermal ablation technique. We briefly explain its biophysical principles and general technical aspects, describe currently available technologies, and summarize findings from clinical studies. Additionally, we discuss its safety profile, unresolved issues, and limitations, while also exploring future perspectives.

EXPERT OPINION

Pulsed field ablation offers distinct advantages over traditional thermal ablation methods, such as shorter procedure times and a favorable safety profile due to precise tissue targeting. Future improvements in ablation device design, energy delivery settings, integration with mapping systems, workflow efficiency, ablation protocols, and patient selection criteria are expected to further enhance clinical outcomes.

Catheter Ablation of Atrial Fibrillation: Technique and Future Perspectives

Atrial fibrillation is the most common sustained cardiac arrhythmia with a significant impact on quality of life in terms of symptoms and reduction of functional status. Also, it is associated with an increased risk of mortality, stroke, and peripheral embolism. Catheter ablation for atrial fibrillation has become a well-established treatment, improving arrhythmia outcomes without increasing the risk of serious adverse events compared to antiarrhythmic drug therapy. The field has undergone significant advancements in recent years, yet pulmonary vein isolation continues to be the cornerstone of any atrial fibrillation ablation procedure. The purpose of this review is to provide an overview of the current techniques, emerging technologies, and future directions.

Redo ablation procedures to treat recurrent atrial arrhythmias via a pentaspline pulsed field ablation catheter: a prospective, multicenter experience

BACKGROUND

Patients undergoing atrial fibrillation (AF) catheter ablation may require redo procedures involving pulmonary vein (PV) re-isolation and/or ablation of extra-PV sites. Pulsed field ablation (PFA) offers a highly selective energy source for cardiac tissue, with the potential to reduce collateral damage to adjacent structures. This study aimed to evaluate the feasibility and efficacy of redo ablation using a pentaspline PFA system.

METHODS

Patients undergoing redo procedures with a pentaspline PFA system at three international centers were enrolled. A workflow was established based on rhythm at presentation: sinus rhythm (Group 1), atrial flutter/atrial tachycardia (Group 2), or AF (Group 3). Propensity score matching was used for comparison between PFA- and RF-based redo ablations.

RESULTS

A total of 117 patients were included (Group 1: 64, Group 2: 18, Group 3: 35). PV re-isolation was required in 71.9% and 72.2% of Group 1 and 2 patients, respectively. PFA terminated all cases of non-cavotricuspid isthmus dependent flutter and 45.7% of cases of AF. One major complication (0.9%; frontal cerebral hematoma) was documented. Freedom from atrial tachyarrhythmias at 12 months was 78.3% (95% CI 69.6-84.8%) without statistically significant differences among groups (Group 1: 85.7%; Group 2: 77%; Group 3: 65.5%; p = 0.053). PFA led to similar arrhythmia freedom compared to RF, but with significantly shorter procedural and dwelling times.

CONCLUSION

The adoption of a pentaspline PFA system for repeat ablation procedures was feasible, safe, and effective at 1-year follow-up. No clinical differences were observed between PFA and RF; however, redo PFA cases were significantly shorter.

Dose-dependent ventricular lesion formation using a novel large-area pulsed field ablation catheter: A preclinical feasibility study

BACKGROUND

Pulsed field ablation (PFA) has shown promising data in terms of safety and procedural efficiency for pulmonary vein isolation. Large-area focal PFA catheter designs might be suitable to deliver deep and durable lesions in ventricular myocardium.

OBJECTIVE

We aimed to investigate the dose-response of a novel large-area focal 3-dimensional (3D)-enabled map-and-ablate PFA catheter for ventricular ablation in a chronic preclinical swine model.

METHODS

An 8F catheter with a 9-mm hexaspline tip was used for 3D mapping of both ventricles in a porcine model. Using a PFA generator with a proprietary waveform optimized for the catheter, left and right ventricular lesions were placed with either a monopolar or bipolar ablation vector and with 1, 2, or 4 applications per site (2.0 kV/application). Tissue contact was ensured by intracardiac echocardiography and electrograms. The animals were kept alive for 1 week. Ablation lesions were assessed macroscopically after triphenyl tetrazolium chloride staining and by histopathology.

RESULTS

A total of 69 chronic ventricular lesions from 7 pigs were available for analysis. By stacking 4 PFA applications rather than a single application, median chronic lesion depth increased from 4.8 mm (interquartile range [IQR], 4.1-5.6 mm) to 5.5 mm (IQR, 5.0-6.2 mm; P = .06) with bipolar ablation and from 4.9 mm (IQR, 4.4-5.2 mm) to 6.5 mm (IQR, 5.9-6.9 mm; P = .002) with monopolar ablation. On histologic evaluation, lesion borders were clearly demarcated, with vessels and nerves preserved.

CONCLUSION

A novel large-area focal ablation catheter with the ability for 3D mapping and PFA was able to create dose-dependent deep ventricular lesions durable 1 week after ablation.

A tailored substrate-based approach using focal pulsed field catheter ablation in patients with atrial fibrillation and advanced atrial substrate: Procedural data and 6-month success rates

BACKGROUND

Focal pulsed field ablation (F-PFA) integrated in electroanatomic mapping systems allows tailored lesion sets in patients with atrial fibrillation (AF).

OBJECTIVE

We aimed to determine feasibility, safety, and 6-month outcome of F-PFA for a tailored substrate-based catheter ablation approach in patients with AF and advanced atrial substrate.

METHODS

Consecutive patients with AF and advanced atrial substrate treated by an F-PFA system (CardioFocus) through contact force-sensing catheters integrated in electroanatomic mapping systems were prospectively enrolled. The tailored substrate-based catheter ablation approach included isolation of all pulmonary veins with wide area circumferential ablation, posterior wall isolation, mitral anterior line, and cavotricuspid isthmus ablation, according to substrate. At 6 months, feasibility, arrhythmia recurrence, and safety were evaluated.

RESULTS

In 83 patients (33% female; indexed left atrial volume, 44 ± 15 mL/m2; 80% persistent AF or atrial flutter [AFl]; 57% redo procedures), successful de novo pulmonary vein isolation was performed in 36 patients and pulmonary vein reisolation in 30 patients. Mitral anterior line was performed in 19 patients with atypical AFl or anterior low-voltage areas; posterior wall isolation was performed in 38 patients with low-voltage areas or evoked delayed electrograms during premature atrial extrastimuli; and cavotricuspid isthmus ablation was performed in 24 patients with typical AFl. Median procedural and fluoroscopy times were 115 and 7 minutes, respectively. No complications occurred. At 6 months, arrhythmia recurred in 30 of 83 patients (21 AF; 9 atypical AFl).

CONCLUSION

Tailored substrate-based F-PFA in patients with AF and advanced atrial substrate is safe and effective. Acute procedural success was 100% with 64% freedom from arrhythmias after 6 months.

Acute mitral block: pulse field ablation plus radiofrequency ablation when compared to radiofrequency ablation plus ethanol injection of vein of Marshall

This retrospective study evaluated two groups: patients receiving RFA for PVI, posterior wall isolation, mitral isthmus, and coronary sinus (CS) ablation with adjunctive VOM ethanol injection (VOM/RFA ALL (N = 53)), and patients receiving PVI with PFA using pentaspline catheter followed by mitral isthmus and CS ablation with RFA (PFA PV + PW/RFA MITRAL (N = 12)). We hypothesized that PFA for pulmonary vein isolation (PVI) facilitates mitral block without adjunctive vein of Marshall (VOM) ethanol injection. Mitral block was achieved in 92.5% of VOM/RFA ALL patients and 83.3% of the PFA PV + PW/RFA MITRAL group (p = 0.31). Endocardial ablation time of the mitral isthmus and RF applications required to achieve a complete block were significantly shorter in the VOM/RFA ALL group (208 s vs 356 s, p < 0.01 and 14.5 vs 24.0, p < 0.01, respectively). Adjunctive VOM ethanol injection appears to still have a role for facilitation of mitral isthmus block in the new era of PFA.

Pulsed field ablation for paroxysmal atrial fibrillation with mitral and cavotricuspid isthmus‑dependent atrial flutter: A case report

Pulsed field ablation (PFA), a nonthermal ablative mechanism, has been proven to be effective and safe in clinical application. To date, PFA has been used for only atrial fibrillation (AF) ablation in limited clinical trials. The present study describes a case of paroxysmal AF in which mitral and cavotricuspid isthmus (CTI)-dependent atrial flutter was discovered incidentally during PFA operation and successfully ablated with PFA. This is the first medical record of PFA for AF combined with mitral and CTI atrial flutter. The present case report revealed that PFA can be independently used to treat complex arrhythmias, similar to radiofrequency (RF) ablation, without the need for assistance from other ablation methods. Concurrently, the present study, to the best of the authors' knowledge is the first to report a case using a point-to-point PFA ablation strategy for isthmus ablation. This highlights the potential of PFA in treating diverse arrhythmias across different regions, such as the mitral isthmus and other intricate areas, utilizing a point-to-point PFA ablation strategy.

Electroporation saves the day again: Pulsed-field ablation for phrenic nerve-sparing in right atrial tachycardia

INTRODUCTION

Pulsed-field ablation (PFA) is a novel nonthermal energy that shows unique features that can be of use beyond pulmonary vein ablation, like tissue selectivity or proximity rather than contact dependency.

METHODS AND RESULTS

We report three cases of right focal atrial tachycardias arising from the superior cavoatrial junction and the crista terminalis, in close relationship with the phrenic nerve, effectively ablated using a commercially available PFA catheter designed for pulmonary vein isolation without collateral damage.

CONCLUSION

PFA can be useful for treating right atrial tachycardias involving sites near the phrenic nerve, avoiding the need for complex nerve-sparing strategies.

Pulsed Field Ablation: A Comprehensive Update

One of the recent advancements in the field of cardiac electrophysiology is pulsed field ablation (PFA). PFA is a novel energy modality that does not rely on thermal processes to achieve ablation which, in turn, results in limited collateral damage to surrounding structures. In this review, we discuss the mechanisms, safety, efficacy, and clinical applications of PFA for the management of atrial and ventricular arrhythmias. We also summarize the published pre-clinical and clinical studies regarding this new technology.

Use of pulse field ablation in the treatment of an atrial tachycardia: A case report

This case illustrates the safety and efficacy of pulse field ablation (PFA) in the short and medium term. It could be used to isolate extra pulmonary sites including the posterior wall. PFA could be used in the treatment of atrial tachycardias both focal and reentrant in combination with ultrahigh density electroanatomic mapping. It is also important to understand that different catheter shapes are available and their use can be tailored to the targeted anatomical site.

Pulmonary vein isolation durability and lesion regression in patients with recurrent arrhythmia after pulsed-field ablation

BACKGROUND

A novel multipolar pulsed-field ablation (PFA) catheter has recently been introduced for pulmonary vein isolation (PVI). Pre-market data showed high rates for PVI-durability during mandatory remapping studies.

OBJECTIVE

To present post-market data in patients with recurrent arrhythmias.

METHODS

Consecutive patients undergoing a redo procedure after an index PFA PVI using a bipolar-biphasic PFA system were included. 3-D electro-anatomical maps (3D-EAM) on redo procedure were compared to the 3D-EAM acquired after ablation during the index procedure. PVI durability was assessed on a per-vein and per-patient level and the sites of reconnections were identified. Furthermore, lesion extent around veins with durable isolation was compared to study lesion regression.

RESULTS

Of 341 patients treated with a PFA PVI, 29 (8.5%) underwent a left atrial redo ablation due to arrhythmia recurrence. At the end of the index procedure, 110/112 veins (98%, four common ostia) were isolated. On redo procedures performed a median of 6 months after the first ablation, 3D-EAM identified 69/110 (63%) PVs with durable isolation. In 6 (21%) patients, all PVs were durably isolated. Reconnections were more often found on the right-sided veins and on the anterior aspects of the upper veins. Only minor lesion regression was observed between the index and redo procedure (a median of 3 mm (0 - 9.5) on the posterior wall).

CONCLUSION

In patients with arrhythmia recurrence after PFA PVI using a first-generation PFA device, durable isolation was observed in 63% of the veins and 21% of the patients showed durable isolation of all previously isolated veins.

Pulsed Field Ablation for Atrial Fibrillation: Mechanisms, Advantages, and Limitations

Pulsed field ablation with irreversible electroporation for the treatment of atrial fibrillation involves tissue-specific and non-thermal energy-induced cell necrosis, which helps avoid complications, such as pulmonary vein stenosis, atrial collateral tissue damage, and extensive atrial structural damage, often encountered with traditional thermal ablation. In existing clinical trials, pulsed field ablation has shown excellent effects on pulmonary vein isolation in patients with paroxysmal and persistent atrial fibrillation. Pulsed field ablation is easy, simple, and quick and can reduce iatrogenic injury. Therefore, the application of pulsed field ablation technology in the treatment of atrial fibrillation has a promising future. Notably, the adjustment of parameters in pulsed field ablation with different ablation catheter systems can strongly affect the area and depth of the necrotic myocardium, which greatly affects the likelihood of atrial fibrillation recurrence and incidence of adverse complications after ablation. In this paper, we review the mechanisms, advantages, and limitations of pulsed field ablation based on the results of a series of previous studies and provide ideas and directions for future research.

Contemporary catheter ablation of complex atrial tachycardias after prior atrial fibrillation ablation: pulsed field vs. radiofrequency current energy ablation guided by high-density mapping

AIMS

Catheter ablation (CA) of post-ablation left atrial tachycardias (LATs) can be challenging. So far, pulsed field ablation (PFA) has not been compared to standard point-by-point radiofrequency current (RFC) energy for LAT ablation. To compare efficacy of PFA vs. RFC in patients undergoing CA for LAT.

METHODS AND RESULTS

Consecutive patients undergoing LAT-CA were prospectively enrolled (09/2021-02/2023). After electro-anatomical high-density mapping, ablation with either a pentaspline PFA catheter or RFC was performed. Patients were matched 1:1. Ablation was performed at the assumed critical isthmus site with additional ablation, if necessary. Right atrial tachycardia (RAT) was ablated with RFC. Acute and chronic success were assessed. Fifty-six patients (n = 28 each group, age 70 ± 9 years, 75% male) were enrolled.A total of 77 AT (n = 67 LAT, n = 10 RAT; 77% macroreentries) occurred with n = 32 LAT in the PFA group and n = 35 LAT in the RFC group. Of all LAT, 94% (PFA group) vs. 91% (RFC group) successfully terminated to sinus rhythm or another AT during ablation (P = 1.0). Procedure times were shorter (PFA: 121 ± 41 vs. RFC: 190 ± 44 min, P < 0.0001) and fluoroscopy times longer in the PFA group (PFA: 15 ± 9 vs. RFC: 11 ± 6 min, P = 0.04). There were no major complications. After one-year follow-up, estimated arrhythmia free survival was 63% (PFA group) and 87% (RFC group), [hazard ratio 2.91 (95% CI: 1.11-7.65), P = 0.0473].

CONCLUSION

Pulsed field ablation of post-ablation LAT using a pentaspline catheter is feasible, safe, and faster but less effective compared to standard RFC ablation after one year of follow-up. Future catheter designs and optimization of the electrical field may further improve practicability and efficacy of PFA for LAT.