Effect of Epicardial Pulsed Field Ablation Directly on Coronary Arteries

Pulsed Field Ablation Using a Lattice-Tip Catheter for Treatment of Ventricular Tachycardias

The inability to create durable, high-quality lesions in the ventricles has limited ventricular tachycardia (VT) ablation outcomes. With pulsed field ablation (PFA), a new modality offers the potential to overcome limitations of conventional, thermal ablation. The lattice-tip catheter's design makes it a promising and versatile tool for ventricular ablation. Preclinical studies have shown that PFA using this system can penetrate scar and fat, create deep lesions, and address difficult ablation targets. Clinical data are scarce but suggest acute feasibility and safety. More research is necessary to evaluate whether this novel ablation system could take VT ablation to the next level.

Catheters and Tools with Pulsed Field Ablation: Pentaspline Farawave

Pulsed field ablation (PFA) is an emerging technology in cardiac electrophysiology that uses pulsed electrical fields to precisely target myocardial tissue. Both preclinical and randomized clinical trials have confirmed the safety and efficacy of using the Farawave pentaspline PFA catheter to treat paroxysmal atrial fibrillation (AF). Ongoing clinical trials are exploring its potential for treating patients with persistent AF and other arrhythmias beyond the left atrium. This review summarizes the development of the Farawave pentaspline PFA catheter, evidence for the safety and efficacy in treating AF, and future directions for its use in cardiac electrophysiology.

Current Safety Profile of Pulse Field Ablation: Not Everything that Shines Is Gold

Pulse field ablation is a novel, non-thermal alternative for catheter ablation of atrial fibrillation. Preclinical and early clinical studies have demonstrated a favorable safety profile with significant reductions in esophageal and pulmonary vein injury compared to radiofrequency ablation. However, there are still procedural and energy-related complications inherent to electroporation, tissue selectivity, and energy-dosing. Minimizing the frequency of application and extent of energy, as well as careful selection of the energy source, may mitigate these adverse events. There remains controversy and a lack of long-term outcomes, highlighting the need for further evaluation.

Pulsed Field Ablation in Ventricular Arrhythmias

Pulsed field ablation (PFA) is a novel nonthermal energy source for catheter ablation, which is potentially useful also for ablation of ventricular arrhythmias since it mitigates the risk of collateral damage to adjacent tissues and may better penetrate through the scar tissue. Solid-tip PFA within the great cardiac vein appears to be advantageous for arrhythmias originating from the left ventricular summit. The use of a large-footprint catheter that toggles between radiofrequency current and PFA may provide an additional advantage since it allows the development of larger lesions to modify myocardial substrate. More experience is expected in the next few years.

Effect of Pulsed-Field Ablation on Human Coronary Arteries: A Longitudinal Study With Intracoronary Imaging

BACKGROUND

Pulsed-field ablation (PFA) is known to cause acute coronary spasm. Whether this translates into long-term coronary artery stenosis is unknown.

OBJECTIVES

This study sought to evaluate changes in coronary artery after PFA for atrial flutter.

METHODS

After pulmonary vein isolation with PFA (Farapulse; Boston Scientific), patients undergoing ablation of the mitral isthmus (MI) or cavotricuspid isthmus (CTI) were included. They underwent coronary angiography and optical coherence tomography (OCT) before and immediately after ablation. Bolus intracoronary nitroglycerine was given before and throughout ablation. Three months after ablation, patients underwent repeated OCT.

RESULTS

A total of 21 patients were included. 1 patient did not undergo PFA owing to the incidental finding of a critical coronary lesion in close proximity to the area to be ablated. Another patient defaulted postprocedure imaging follow-up. 19 patients had paired imaging data, in 20 coronary vessels (18 right coronary and 2 left circumflex arteries). At the ablation site, at 3 months, vascular wall area increased by a median of 0.40 mm2 (Q1-Q3: 0.13-0.71 mm2; P < 0.01), or 17.1% (Q1-Q3: 8.6%-31.0%). The median reduction in the luminal area was 0.70 mm2 (Q1-Q3: 0.18-1.30 mm2; P < 0.01), or 10.1% (Q1-Q3: 4.7%-16.2%). These changes were not observed in a predetermined reference site remote from the ablation target.

CONCLUSIONS

PFA of the CTI and MI is associated with acute spasm, and mild narrowing of the coronary arteries at 3 months. Although intracoronary vasodilator therapy may prevent or treat acute spasm, the risk of arterial stenosis remains, calling for heightened vigilance and long-term follow-up.

Pulsed Field Ablation: A Review of Preclinical and Clinical Studies

Pulsed field ablation (PFA) is an emerging technology that utilizes ultra-short high-voltage electric pulses to create nanopores in cell membranes, leading to cell death through irreversible electroporation (IRE). PFA is touted to be highly tissue-selective, which may mitigate the risk of collateral injury to vital adjacent structures. In the field of cardiac electrophysiology, initial studies have shown promising results for acute pulmonary vein isolation (PVI) and lesion durability, with overall freedom from recurrent atrial arrhythmia comparable to traditional thermal ablation modalities. While further large studies are required for long-term efficacy and safety data, PFA has the potential to become a preferred energy source for cardiac ablation for some indications. This review outlines the basic principles and biophysics of IRE and its application to cardiac electrophysiology through a review of the existing preclinical and clinical data.

3D mapping quest: How far can we see with recent advances in 3D mapping?

Recent advances in three-dimensional (3D) ultra-high-density mapping systems have uncovered previously unknown mechanisms underlying various arrhythmias. This clinical review, titled "3D Mapping Quest," focuses on the recently uncovered mechanisms of four types of arrhythmias. (1) To elucidate the precise mechanisms underlying atrial fibrillation (AF), ultra-high-density mapping with adequate spatial and temporal resolution is essential. Various mapping systems have been employed to investigate the chaotic activation during AF. The question remains: Is the AF driver characterized by focal activation or rotational activation? A novel mapping strategy is expected to provide the answer. (2) In atrioventricular nodal reentrant tachycardia (AVNRTs), 3D mapping revealed that the pivot point of activation at the lower end of a functional block line extending vertically downward from the His-bundle area, or a fractionated potential observed during AVNRT, can be targeted for slow pathway ablation. Either approach may prevent unnecessary radiofrequency applications while maintaining the success rate. (3) In premature ventricular contractions originating from the left ventricular summit, 3D mapping has enabled precise identification of the optimal endocardial ablation sites. By performing long-duration ablation at these optimal endocardial sites, the ablation outcomes have improved. (4) In scar-related reentrant ventricular tachycardia (VT), substrate mapping focusing on wavefront discontinuity has allowed for the identification of specific ablation targets within the broad scar. High-density VT activation mapping has revealed the complexity of the circuit structure, such as the 3D VT circuit. The VT circuit delineation on the cardiac surface is conceptualized as a cross-section of a hyperboloid model. Thus, it is anticipated that integrating histological and electrophysiological insights with advanced ultra-high-density mapping technologies will further facilitate a comprehensive understanding of the mechanisms.

Fundamentals of System Design for Cardiac Pulsed Field Ablation: Optimization of Safety, Efficacy, and Usability

The goal of a cardiac pulsed field ablation (PFA) system is to provide safe, effective, and usable therapy for the treatment of cardiac arrhythmias. Achieving this goal is a complex exercise in system design, requiring optimization of catheter, waveform, and dosing. This optimization is often iterative, as myriad design factors are balanced to achieve the goal while making use of computational modeling, bench testing, preclinical animal studies, and human clinical studies to evaluate system performance. It is important for both engineers and clinicians to understand the fundamentals of cardiac PFA system design in order to partner to continuously improve performance of this expanding ablation modality.

Lesion Formation in Cardiac Pulsed-Field Ablation: Acute to Chronic Cellular Level Changes

As pulsed-field ablation (PFA) emerges as a promising therapy for atrial arrhythmias, an understanding of the cellular injury to cardiac tissue is critical to evaluating and interpreting results for each PFA system. This review aims to detail the mechanism of cell death for PFA, compare the cell death mechanism to thermal ablation modalities, clarify common histology markers, detail the progression of PFA lesions from the acute, to subacute, to chronic maturation states, and discuss clinical indicators of PFA lesions.

Coronary artery injury in pulsed field ablation

PURPOSE OF REVIEW

Although pulsed field ablation (PFA) has emerged as an innovative nonthermal catheter ablation modality, recent reports raise concerns about its potential impact on nearby coronary arteries. This review provides a comprehensive overview of the current understanding and future directions regarding the effects of PFA on or near coronary arteries.

RECENT FINDINGS

Clinical studies have demonstrated the risks of acute transient vasospasm after delivery of PFA, especially with ablation of structures in proximity to the coronary arteries, such as the cavotricuspid and mitral isthmuses. The clinical incidence has been reported to be approximately 0.14%, according to the largest multicenter registry. Nitroglycerin pretreatment has been demonstrated to mitigate vasospastic events. However, early preclinical models indicate that chronic neointimal hyperplasia, tunica media fibrosis and mild coronary artery narrowing may occur, suggesting long-term coronary injury after delivering PFA near coronary arteries.

SUMMARY

Despite reducing collateral tissue damage compared with thermal methods, PFA near coronary arteries may require careful procedural planning and proactive use of nitroglycerin to reduce coronary vasospasm. Further research is essential to elucidate the mechanisms underlying PFA-induced coronary spasm, optimize catheter design and placement, and assess the long-term coronary health implications.

Comparing pulsed field ablation with very high-power and high-power short-duration radiofrequency ablation for atrial fibrillation: a systematic review and meta-analysis

BACKGROUND

Catheter ablation is a key treatment for atrial fibrillation (AF), with high-power, very high-power short-duration and pulsed field ablation (PFA) being efficient options. However, direct comparisons between these techniques are lacking.

OBJECTIVE

We performed a systematic review and meta-analysis, which included predominantly observational studies (four retrospective and one prospective study), to compare PFA and High-power short-duration (HPSD) and very high-power short-duration (vHPSD) radiofrequency (RF) ablation in patients with AF.

METHODS

We searched PubMed, Embase and Cochrane Central. Outcomes of interest included: Arrhythmia-free survival (AF, atrial flutter, and atrial tachycardia recurrences 30 s during follow-up after a 1-month blanking period), procedure time, fluoroscopy time, fluoroscopy dose, complications overall. Statistical analysis was performed using the R program (version 4.3.2). Heterogeneity was assessed with I2 statistics.

RESULTS

Our meta-analysis included 1,255 patients from 5 studies, with a mean age ranging from 63 to 68 years. Among them, 554 (45.2%) underwent pulsed field ablation (PFA) and 701 (55.8%) received high/very high potential short-duration ablation. PFA improved arrhythmia-free survival (RR 1.05; 95% CI 1.002-1.120; P = 0.004; I2 = 0%) and reduced procedure time (MD -29.95 min; 95% CI -30.90 to -29.00; P < 0.01; I2 = 0%). However, PFA increased fluoroscopy time (MD 6.33 min; 95% CI 1.65 to 11.01; P < 0.01; I2 = 98%) and showed no significant difference in overall complications (RR 0.88; 95% CI 0.38-2.02; P = 0.756; I2 = 47%), cardiac tamponade (RR 1.62; 95% CI 0.27-9.85; P = 0.599; I2 = 40%), or stroke/transient ischemic attack (TIA) incidence (RR 0.64; 95% CI 0.15-2.80; P = 0.555; I2 = 0%). PFA was associated with a reduced need for redo procedures (RR 0.66; 95% CI 0.45-0.97; P = 0.036; I2 = 0%) and did not significantly affect the fluoroscopy dose (MD 896.86 mGy·cm2; 95% CI -1269.44 to 3063.15; P = 0.42; I2 = 39%).

CONCLUSION

In this meta-analysis, PFA was associated with improved arrhythmia-free survival and reduced procedure time, although it resulted in increased fluoroscopy time. PFA and high/very high power short-duration ablation yielded similar outcomes regarding overall complications, cardiac tamponade, and stroke/TIA incidence. Both techniques demonstrated comparable efficacy in treating atrial fibrillation.

Catheter ablation using pulsed-field energy: Do we finally have the magic wand to defeat atrial fibrillation?

Clinical outcomes of catheter ablation remain suboptimal in patients with atrial fibrillation (AF), particularly in those with persistent AF, despite decades of research, clinical trials, and technological advancements. Recently, pulsed-field ablation (PFA), a promising non-thermal technology, has been introduced to improve procedural outcomes. Its unique feature of myocardial selectivity offers safety advantages by avoiding potential harm to vulnerable adjacent structures during AF ablation. However, despite the global enthusiasm within the electrophysiology community, recent data indicate that PFA is still far from being a "magic wand" for addressing such a complex and challenging arrhythmia as AF. More progress is needed in mapping processes rather than in ablation technology. This editorial reviews relevant available data and explores future research directions for PFA.

A novel focal lattice-tip catheter toggling between pulsed field energy and radiofrequency for atrial arrhythmia ablation: Results from a real-world, multicenter registry

BACKGROUND

A novel focal lattice-tip catheter allowing the delivery of either pulsed field (PF) or radiofrequency (RF) energy has recently received regulatory approval. The technology features a proprietary 3-dimensional electroanatomic mapping system.

OBJECTIVE

We describe the first real-world and multicenter experience.

METHODS

Consecutive AF patients undergoing first-time or redo atrial tachyarrhythmia ablation with the Affera system were prospectively enrolled at 3 different centers. PF was the only energy source allowed when ablating the posterior left atrium; anterior applications were performed with either RF (PF/RF strategy) or PF (PF/PF strategy) on the basis of the operator's preference. The primary efficacy end point included acute electrical isolation of pulmonary veins and posterior wall or bidirectional block in case of linear lesions.

RESULTS

The study included 130 patients (mean age, 67 ± 10 years; 63.8% [n = 83] male; 61.5% [n = 80] nonparoxysmal AF; 55.4% first-time AF ablation). First-time pulmonary vein isolation was performed in 72 patients: RF/PF in 13 (18.1%) patients and PF/PF in the remaining 59 (81.9%); first-pass isolation for pulmonary vein and posterior wall was achieved in 100% of cases. A total of 289 ablation lines were performed (roof line, 91 patients; inferior line, 83 patients; anterior mitral line, 32 patients; posterior mitral line, 45 patients; cavotricuspid isthmus line, 38 patients). First-pass isolation and primary efficacy end point were 96.2% (roof line, 100%; inferior line, 100%; anterior mitral line, 96.9%; posterior mitral line, 84.4%; cavotricuspid isthmus, 92.1%) and 100%, respectively. We had 2 (1.5%) major complications: 1 ST-segment elevation at the inferolateral leads requiring intracoronary administration of nitrate and 1 complete atrioventricular block.

CONCLUSION

Catheter ablation with a novel 9-mm lattice-tip catheter confirmed high efficacy and safety in a real-world scenario.

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.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society.

Pulsed Field Ablation of Paroxysmal Supraventricular Tachycardia: A Prospective Multicenter Single-Arm Study in China

BACKGROUND

Pulsed field ablation (PFA) has gained attention in cardiac electrophysiology, but data on its application to paroxysmal supraventricular tachycardia are limited. This study aimed to assess the feasibility and safety of PFA and its combination with radiofrequency ablation for treating paroxysmal supraventricular tachycardia.

METHODS

A prospective, multicenter, single-arm study was conducted across 8 centers in China. Patients with atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia, or Wolff-Parkinson-White syndrome underwent ablation using a focal point dual-mode PFA/radiofrequency ablation catheter. PFA was used to achieve acute ablation success, with consolidation using PFA for atrioventricular nodal reentrant tachycardia or near-His accessory pathways and radiofrequency ablation for far-His accessory pathways. Primary and secondary end points were acute ablation success and 180-day follow-up success, respectively.

RESULTS

A total of 158 patients (77 with atrioventricular nodal reentrant tachycardia, 63 with atrioventricular reentrant tachycardia, 16 with Wolff-Parkinson-White, and 2 with both atrioventricular nodal reentrant tachycardia and atrioventricular reentrant tachycardia) completed the trial. Acute ablation was successful in 157 patients (99.37%). The skin-to-skin procedure time was 89.9±35.5 min. The median number of PFA discharges was 12 (8-19) with a median effective PFA discharge time of 4.6 (3.2-6.4) ms. Five patients (4 with atrioventricular reentrant tachycardia and 1 with Wolff-Parkinson-White syndrome) experienced paroxysmal supraventricular tachycardia recurrence during the 180-day follow-up period. One patient had a transient first-degree atrioventricular block resolving in 12 hours, and one patient had a transient third-degree atrioventricular block resolving in 24 hours. No permanent atrioventricular block or other adverse events occurred during the ablation procedure or 180-day follow-up period.

CONCLUSIONS

PFA demonstrated the feasibility of the treatment of SVT. Reversible first- and third-degree atrioventricular blocks were observed following ablation in one patient each. The preliminary results indicated the safety and feasibility of a combination of PFA and radiofrequency ablation treatment for atrioventricular accessory pathways although it is impossible to determine the relative contribution of PFA.

Coronary Spasm Due to Pulsed Field Ablation: A State-of-the-Art Review

With the ever-growing population of patients undergoing cardiac ablation with pulsed electric fields, there is a need to understand secondary effects from the therapy. Coronary artery spasm is one such effect that has recently emerged as the subject of further investigation in electrophysiology literature. This review aims to elucidate the basic anatomy underlying vascular spasm due to pulsed electric fields and the effects of irreversible electroporation on coronary arteries. This review also aims to gather the current preclinical and clinical data regarding the physiology and function of coronary arteries following electroporation.

Mapping and ablation of ventricular tachycardia using dual-energy lattice-tip focal catheter: early feasibility and safety study

AIMS

Catheter ablation is an effective treatment method for recurrent ventricular tachycardias (VTs). However, at least in part, procedural and clinical outcomes are limited by challenges in generating an adequate lesion size in the ventricular myocardium. We investigated procedural and clinical outcomes of VT ablation using a novel 'large-footprint' catheter that allows the creation of larger lesions either by radiofrequency (RF) or by pulsed field (PF) energy.

METHODS AND RESULTS

In prospectively collected case series, we describe our initial experience with VT ablation using a lattice-tip, dual-energy catheter (Sphere-9, Medtronic), and a compatible proprietary electroanatomical mapping system (Affera, Medtronic). The study population consisted of 18 patients (aged 55 ± 15 years, one woman, structural heart disease: 94%, ischaemic heart disease: 56%, left ventricular ejection fraction: 34 ± 10%, electrical storm: 22%) with recurrent sustained VTs and ≥1 previously failed endocardial RF ablation with conventional irrigated-tip catheter in 66% of patients. On average, 12 ± 7 RF and 8 ± 9 PF applications were delivered per patient. In three-fourths of patients undergoing percutaneous epicardial ablation, spasms in coronary angiography were observed after PF applications. All resolved after intracoronary administration of nitrates. No acute phrenic nerve palsy was noted. One patient suffered from a stroke that resolved without sequelae. Post-ablation non-inducibility of VT was achieved in 89% of patients. Ventricular-arrhythmia-free survival at three months was 78%.

CONCLUSION

VT ablation using a dual-energy lattice-tip catheter and a novel electroanatomical mapping system is feasible. It allows rapid mapping and effective substrate modification with good outcomes during short-term follow-up.

Focal monopolar pulsed field ablation from within the great cardiac vein for idiopathic premature ventricular contractions after failed radiofrequency ablation

BACKGROUND

Idiopathic epicardial premature ventricular contractions (PVCs) originating from the left ventricular summit are difficult to eliminate.

OBJECTIVE

The purpose of this study was to describe the feasibility and procedural safety of monopolar biphasic focal pulsed field ablation (F-PFA) from within the great cardiac vein (GCV) for treatment of idiopathic epicardial PVCs.

METHODS

In 4 pigs, F-PFA (Centauri, CardioFocus) was applied from within the GCV followed by macroscopic gross analysis. In 4 patients with previously failed radiofrequency ablation, electroanatomic mapping was used to guide F-PFA from within the GCV and the ventricular outflow tracts. Coronary angiography and optical coherence tomography (OCT) were performed in 2 patients.

RESULTS

In pigs, F-PFA from within the GCV (5 mm away from the coronary arteries) resulted in myocardial lesions with a maximal depth of 4 mm, which was associated with nonobstructive transient coronary spasms. In patients, sequential delivery of F-PFA in the ventricular outflow tracts and from within the GCV eliminated the PVCs. During F-PFA delivery from within the GCV with prophylactic nitroglycerin application, coronary angiography showed no coronary spasm when F-PFA was delivered >5 mm away from the coronary artery and a transient coronary spasm without changes in a subsequent OCT, when F-PFA was delivered directly on the coronary artery. Intracardiac echocardiography and computed tomography integration was used to monitor F-PFA delivery from within the GCV. There were no immediate or short-term complications.

CONCLUSION

Sequential mapping-guided F-PFA from endocardial ventricular outflow tracts and from within the GCV is feasible with a favorable procedural safety profile for treatment of epicardial PVCs.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society.

Pulsed field ablation as a feasible option for the treatment of epicardial left ventricular summit premature complex foci near the coronary arteries: a case report

Background

Radiofrequency catheter ablation in the left ventricular summit region is a challenging procedure due to proximity to the coronary arteries. Pulsed field ablation, a novel non-thermal ablation modality, does not cause damage to coronary arteries and may be used in the left ventricular summit region.

Case summary

We describe a 45-year-old symptomatic patient with epicardial left ventricular summit premature ventricular complexes. Successful ablation of the focus was achieved by pulsed field ablation via a subxiphoid epicardial approach. Radiofrequency ablation would most likely have been ineffective due to the epicardial fat layer and potentially unsafe due to the proximity to the coronary arteries. Six months after ablation, the patient was asymptomatic and without ventricular ectopy.

Discussion

For the first time, epicardial pulsed field ablation was successfully used for ablation of left ventricular summit extrasystole, where radiofrequency ablation could not be used because of the proximity of the coronary arteries. We conclude that pulsed field ablation might be a feasible option for this indication.

Comparative Efficacy and Safety of Pulsed Field Ablation Versus Radiofrequency Ablation of Idiopathic LV Arrhythmias

BACKGROUND

Comparative efficacy and safety data on radiofrequency ablation (RFA) versus pulsed field ablation (PFA) for common idiopathic left ventricular arrhythmia (LV-VAs) locations are lacking.

OBJECTIVES

This study sough to compare RFA with PFA of common idiopathic LV-VAs locations.

METHODS

Ten swine were randomized to PFA or RFA of LV interventricular septum, papillary muscle, LV summit via distal coronary sinus, and LV epicardium via subxiphoid approach. Ablations were delivered using an investigational dual-energy (RFA/PFA) contact force (CF) and local impedance-sensing catheter. After 1-week survival, animals were euthanized for lesion assessment.

RESULTS

A total of 55 PFA (4 applications/site of 2.0 KV, target CF ≥10 g) and 36 RFA (CF ≥10 g, 25-50 W targeting ≥50 Ω local impedance drop, 60-second duration) were performed. LV interventricular septum: average PFA depth 7.8 mm vs RFA 7.9 mm (P = 0.78) and no adverse events. Papillary muscle: average PFA depth 8.1 mm vs RFA 4.5 mm (P < 0.01). Left ventricular summit: average PFA depth 5.6 mm vs RFA 2.7 mm (P < 0.01). Steam-pop and/or ventricular fibrillation in 4 of 12 RFA vs 0 of 12 PFA (P < 0.01), no ST-segment changes observed. Epicardium: average PFA depth 6.4 mm vs RFA 3.3 mm (P < 0.01). Transient ST-segment elevations/depressions occurred in 4 of 5 swine in the PFA arm vs 0 of 5 in the RFA arm (P < 0.01). Angiography acutely and at 7 days showed normal coronaries in all cases.

CONCLUSIONS

In this swine study, compared with RFA, PFA of common idiopathic LV-VAs locations produced deeper lesions with fewer steam pops. However, PFA was associated with higher rates of transient ST-segment elevations and depressions with direct epicardium ablation.

Focal Pulsed Field Ablation for Premature Ventricular Contractions: A Multicenter Experience

BACKGROUND

Pulsed field ablation (PFA) is a novel technology for catheter-based atrial arrhythmia treatment. Evidence of its application for ventricular arrhythmia ablation is still limited. In this study, we describe the feasibility and efficacy of focal PFA for premature ventricular contraction (PVC) ablation.

METHODS

A prospective cohort of 20 patients referred for PVC ablation at 2 centers was enrolled, regardless of the presence of structural heart disease, PVC morphology, or previous ablation attempts. All procedures were performed using the CENTAURI System in combination with contact force sensing catheters and 3-dimensional electroanatomical mapping systems. Energy output and the number of applications were left to the operator's discretion.

RESULTS

Eleven (55%) procedures were conducted under general anesthesia, 6 (30%) under deep sedation, and 3 (15%) under light sedation. Muscular contraction was observed in one case (5%). Median procedural and fluoroscopy times were 95.5 and 6.55 minutes, respectively. The median number of PFA applications was 8 with a median contact force of 10g. A statistically significant (76%) reduction was observed in mean peak-to-peak bipolar electrogram voltage before and after ablation (0.707 versus 0.098 mV; P=0.008). Ventricular irritative firing was observed in 11 (55%) patients after PFA. The median follow-up was 120 days. Acute procedural success was achieved in 17 of 20 (85% [95% CI, 0.70-1]) patients. Two of the patients with procedural failure had late success with >80% clinical PVC burden suppression during follow-up, and 2 of 17 patients with acute success had late PVC recurrence, which accounts for a total of 17 of 20 (85% [95% CI, 0.70-1]) patients with chronic success. Transient ST-segment depression occurred in 1 patient, and the right bundle branch block was induced in 2 others (permanently only in one case).

CONCLUSIONS

PVC ablation using a focal PFA is feasible, effective, and safe, with promising acute and long-term results in several ventricular locations. Irritative firing is frequently observed. Coronary evaluation should be considered when targeting the outflow tract.

Percutaneous LAAO and Pulsed-Field Isolation in a Canine Model: Feasibility and Safety Evaluation

In this study, we investigated the feasibility, safety, and efficiency of using a novel device system to perform percutaneous left atrial appendage occlusion concomitant with left atrial appendage electrical isolation (LAAEI) via pulsed field ablation. In the acute phase, LAAEI was successful in 10 of 10 canines. At follow-up, full endothelialization was observed in 5 of 5 (100%) cases at 6 months. LAAEI was durable in 8 of 10 (80.00%) canines. Histologic examination in 4 of 6 LAAs with durable isolation showed transmural scars comprising fibrosis and fat. No pericardial effusion or phrenic paralysis was observed at follow-up. This preliminary study provides the scientific basis for first-in-human studies.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society (HRS), the Asia Pacific HRS, and the Latin American HRS.

Severe ST-segment elevation and AV block during pulsed-field ablation due to vasospastic angina - a novel observation

Catheter ablation of atrial fibrillation using non-thermal electroporation represents a promising ablation modality due to its believed superior safety profile. Still, if electroporation is delivered in proximity to a coronary artery, vasospasms can occur. We report the first case of severe right coronary artery vasospasm resulting in ST-segment elevation and AV block despite a remote distance from the ablation site to the right coronary artery, indicating a different mechanism. In this case, electroporation most likely triggered a previously unknown Prinzmetal vasospastic angina in the patient, resulting in the coronary vasospasm. Thus, meticulous monitoring of ST-segment changes following PFA delivery even from regions remote to coronary arteries is required.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society .

Cardiac blood vessels and irreversible electroporation: findings from pulsed field ablation

The clinical use of irreversible electroporation in invasive cardiac laboratories, termed pulsed field ablation (PFA), is gaining early enthusiasm among electrophysiologists for the management of both atrial and ventricular arrhythmogenic substrates. Though electroporation is regularly employed in other branches of science and medicine, concerns regarding the acute and permanent vascular effects of PFA remain. This comprehensive review aims to summarize the preclinical and adult clinical data published to date on PFA's effects on pulmonary veins and coronary arteries. These data will be contrasted with the incidences of iatrogenic pulmonary vein stenosis and coronary artery injury secondary to thermal cardiac ablation modalities, namely radiofrequency energy, laser energy, and liquid nitrogen-based cryoablation.

Opportunities and Challenges in Catheter-Based Irreversible Electroporation for Ventricular Tachycardia

The use of catheter-based irreversible electroporation in clinical cardiac laboratories, termed pulsed-field ablation (PFA), is gaining international momentum among cardiac electrophysiology proceduralists for the non-thermal management of both atrial and ventricular tachyrhythmogenic substrates. One area of potential application for PFA is in the mitigation of ventricular tachycardia (VT) risk in the setting of ischemia-mediated myocardial fibrosis, as evidenced by recently published clinical case reports. The efficacy of tissue electroporation has been documented in other branches of science and medicine; however, ventricular PFA's potential advantages and pitfalls are less understood. This comprehensive review will briefly summarize the pathophysiological mechanisms underlying VT and then summarize the pre-clinical and adult clinical data published to date on PFA's effectiveness in treating monomorphic VT. These data will be contrasted with the effectiveness ascribed to thermal cardiac ablation modalities to treat VT, namely radiofrequency energy and liquid nitrogen-based cryoablation.

Pulsed Field Ablation of Atrial Fibrillation: An Initial Australian Single-Centre Experience

BACKGROUND

Pulsed field ablation (PFA) is a newer ablation energy source with the potential to reduce complications and improve efficacy compared to conventional thermal atrial fibrillation (AF) ablation. This study aimed to present an initial single-centre Australian experience of PFA for AF ablation.

METHODS

Initial consecutive patients undergoing PFA for paroxysmal or persistent AF at a single centre were included. Baseline patient characteristics, procedural data and clinical outcomes were collected prospectively at the time of the procedure. Patients were followed up at 3 months and 6-monthly thereafter.

RESULTS

In total, 100 PFA procedures were performed in 97 patients under general anaesthesia. All pulmonary veins (403 of 403) were successfully isolated acutely. Median follow-up was 218 days (range, 16-343 days), and the Kaplan-Meier estimate for freedom from atrial arrhythmias at 180 days was 87% (95% confidence interval 79%-95%). Median procedure time was 74 minutes (range, 48-134 minutes). Median fluoroscopy dose-area product was 345 μGym2 (interquartile range, 169-685 μGym2). Two (2%) pseudoaneurysm vascular access complications occurred. There were no cases of thromboembolic complications, stroke, phrenic nerve palsy, pulmonary vein stenosis, atrio-oesophageal fistula, or pericardial tamponade.

CONCLUSIONS

Pulsed field ablation can be performed safely and efficiently, with encouraging efficacy in early follow-up. Further data and clinical trials will be required to assess the comparative utility of PFA in contemporary AF ablation practice.

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.

How intramyocardial fat can alter the electric field distribution during Pulsed Field Ablation (PFA): Qualitative findings from computer modeling

Even though the preliminary experimental data suggests that cardiac Pulsed Field Ablation (PFA) could be superior to radiofrequency ablation (RFA) in terms of being able to ablate the viable myocardium separated from the catheter by collagen and fat, as yet there is no formal physical-based analysis that describes the process by which fat can affect the electric field distribution. Our objective was thus to determine the electrical impact of intramyocardial fat during PFA by means of computer modeling. Computer models were built considering a PFA 3.5-mm blunt-tip catheter in contact with a 7-mm ventricular wall (with and without a scar) and a 2-mm epicardial fat layer. High voltage was set to obtain delivered currents of 19, 22 and 25 A. An electric field value of 1000 V/cm was considered as the lethal threshold. We found that the presence of fibrotic tissue in the scar seems to have a similar impact on the electric field distribution and lesion size to that of healthy myocardium only. However, intramyocardial fat considerably alters the electrical field distribution and the resulting lesion shape. The electric field tends to peak in zones with fat, even away from the ablation electrode, so that 'cold points' (i.e. low electric fields) appear around the fat at the current entry and exit points, while 'hot points' (high electric fields) occur in the lateral areas of the fat zones. The results show that intramyocardial fat can alter the electric field distribution and lesion size during PFA due to its much lower electrical conductivity than that of myocardium and fibrotic tissue.