Absence of (sub-)acute cerebral events or lesions after electroporation ablation in the left-sided canine heart

Efficacy and safety of pulsed field ablation for accessory pathways: a pilot study

AIMS

Radiofrequency ablation is used as a first-line therapy for accessory pathways (APs). However, data regarding the effects of pulsed field ablation (PFA) on APs are limited. We sought to evaluate the acute procedural and 6-month success and safety of PFA in a cohort of patients with APs.

METHODS AND RESULTS

A focal contact force-sensing PFA catheter was used for patients with APs. Pulsed field ablation generator generated a bipolar and biphasic waveform (±1000 V) with a duration of 100 ms from the tip of the PFA catheter. A 100% acute procedural success was achieved in 10 conscious patients with APs (7 left anterolateral, 2 left inferolateral, and 1 right posteroseptal APs) including 6 (60%) patients after an initial application. The average total ablation time was 6.3 ± 4.9 s for 4.7 ± 1.8 ablation sites (ASs), including 3.1 ± 2.4 s at targets and 3.2 ± 2.9 s at 3.2 ± 2 bolus ASs. The mean skin-to-skin time was 59.3 ± 15.5 min, and PFA catheter dwell time was 29.4 ± 7.8 min. One patient encountered transient sinus arrest during PFA due to parasympathetic overexcitation. Sinus rhythm was restored in all patients without any significant adverse events during the short-term follow-up.

CONCLUSION

Pulsed field ablation of APs was feasible, effective, and safe. Its efficiency was remarkable for its ultrarapid termination of AP conduction. Further studies are warranted to prove whether utilization of PFA with current parameters can extend to manifold AP ablation.

Characterization of durability and reconnection patterns at time of repeat ablation after single-shot pulsed field pulmonary vein isolation

BACKGROUND

Pulsed field ablation (PFA) is a novel method of cardiac ablation where there is insufficient knowledge on the durability and reconnection patterns after pulmonary vein isolation (PVI). The aim of this study was to characterize the electrophysiological findings at time of repeat procedure in real-world atrial fibrillation (AF) patients.

METHODS

Patients who underwent a repeat procedure (n=26) for symptomatic recurrent arrhythmias after index first-time treatment with single-shot PFA PVI (n=266) from July 2021 to June 2023 were investigated with 3D high-density mapping and ad-hoc re-ablation by radiofrequency or focal PFA.

RESULTS

Index indication for PVI was persistent AF in 17 (65%) patients. The mean time to repeat procedure was 292 ± 119 days. Of the 26 patients (104 veins), complete durable PVI was observed in 11/26 (42%) with a durable vein isolation rate of 72/104 (69%). Two patients (8%) had all four veins reconnected. The posterior wall was durably isolated in 4/5 (80%) of the cases. The predominant arrhythmia mechanism was AF in 17/26 (65%) patients and regular atrial tachycardia (AT) in 9/26 (35%). Reconnection was observed 9/26 (35%) in right superior, 11/26 (42%) in right inferior, 7/26 (27%) in left superior, 5/26 (19%) in left inferior, p=0.31 between veins. The gaps were significantly clustered in the right-sided anterior carina compared to other regions (P=0.009).

CONCLUSIONS

Durable PVI was observed in less than half of the patients at time of repeat procedure. No significant difference in PV reconnection pattern was observed, but the gap location was preferentially located at the anterior aspects of the right-sided PVs. Predominant recurrence was AF. More data is needed to establish lesion formation and durability and AT circuits after PFA.

Focal pulsed field ablation and ultrahigh-density mapping - versatile tools for all atrial arrhythmias? Initial procedural experiences

BACKGROUND

Focal pulsed field ablation (FPFA) is a novel and promising method of cardiac ablation. The aim of this study was to report the feasibility, short-term safety, and procedural findings for a broad spectrum of ablated atrial arrhythmias.

METHODS

Patients (n = 51) scheduled for ablation of atrial arrhythmias were prospectively included and underwent FPFA using the Galvanize CENTAURI generator with energy delivery through commercially available ablation catheters with ultrahigh-density (UHDx) 3D electroanatomic voltage/local activation time map evaluations. Workflow, procedural data, and peri-procedural technical errors and complications are described.

RESULTS

Planned ablation strategy was achieved with FPFA-only in 48/51 (94%) of the cases. Ablation strategy was first-time pulmonary vein isolation (PVI) in 17/51 (36%), repeat ablation in 18/51 (38%), PVI + in 13/51 (28%), and cavotricuspid isthmus block (CTI)-only in 3/51 (6%). The mean procedure time was 104 ± 31 min (first-time PVI), 114 ± 26 min (repeat procedure), 152 ± 36 min (PVI +), and 62 ± 17 min (CTI). Mean UHDx mapping time to assess lesion formation and block after ablation was 7 ± 4 min with 5485 ± 4809 points. First pass acute (linear) isolation with bidirectional block for anatomical lesion sets was 120/124 (97%) for all PVs, 17/17 (100%) for (any) isthmus, and 14/17 (82%) for left atrium posterior wall (LAPW). We observed several time-consuming integration errors with the used ablation system (mean 3.4 ± 3.7 errors/procedure), one transient inferior ST elevation when ablating CTI resolved by intravenous nitroglycerine and one transient AV block requiring temporary pacing for > 24 h.

CONCLUSIONS

FPFA was a highly versatile method to treat atrial arrhythmias with high first-pass efficiency. UHDx revealed acute homogenous low-voltage lesions in ablated areas. More data is needed to establish lesion durability and limitations of FPFA.

Pulsed field ablation in real-world atrial fibrillation patients: clinical recurrence, operator learning curve and re-do procedural findings

BACKGROUND

Pulsed field ablation (PFA) is a novel method of cardiac ablation demonstrated in early pre-clinical and clinical settings. The aim of this study was to report the safety and clinical efficacy of pulmonary vein isolation (PVI) with PFA for real-world atrial fibrillation (AF) patients.

METHODS

All-comer AF patients (n = 121, 59% paroxysmal) were prospectively included and underwent PFA with 100% high-density voltage maps performed after PVI. Clinical outcomes were gathered by chart review.

RESULTS

PVI was achieved with PFA-only in 119 (98%) of the cases. During the implementation phase the mean procedure and fluoroscopy time was reduced from 85 ± 34 to 72 ± 18 min (p = 0.044) and 22 ± 9 to 16 ± 4 (p = 0.034). We observed one phrenic nerve palsy with only partial remission at follow-up. Other adverse events were numerically comparable to standard PVI procedures. Over a mean follow-up of 308 ± 87 days, a total of 22/121 (18.2%) cases experienced clinically significant recurrence or initiation of anti-arrhythmic drugs with Kaplan-Meier event-free estimate at 365 days of 80% (88% for paroxysmal versus 69% for persistent). In five of eight re-do procedures, gaps were primarily located at the right pulmonary veins.

CONCLUSIONS

PFA was a highly efficient method to achieve PVI with reductions in procedure time and fluoroscopy over the implementation period. The procedural data and clinical recurrence rates from initial trials were confirmed in real-life non-selected AF patients. More data is needed to establish lesion durability and limitations of PFA.

Silent cerebral lesions following catheter ablation for atrial fibrillation: a state-of-the-art review

Atrial fibrillation is associated with neurocognitive comorbidities such as stroke and dementia. Evidence suggests that rhythm control-especially if implemented early-may reduce the risk of cognitive decline. Catheter ablation is highly efficacious for restoring sinus rhythm in the setting of atrial fibrillation; however, ablation within the left atrium has been shown to result in MRI-detected silent cerebral lesions. In this state-of-the-art review article, we discuss the balance of risk between left atrial ablation and rhythm control. We highlight suggestions to lower the risk, as well as the evidence behind newer forms of ablation such as very high power short duration radiofrequency ablation and pulsed field ablation.

Multi-modality imaging assessment of microbubbles and cerebral emboli in left ventricular pulsed field ablation

BACKGROUND

Pulsed field ablation (PFA) may have a superior safety profile compared to other technologies, but it has the potential to cause gaseous microbubbles (MB), which may be associated with cerebral emboli. Limited relative safety data has been published regarding PFA in the left ventricle (LV).

METHODS

Healthy and chronic myocardial infarction (MI) swine underwent PFA (monopolar, biphasic, 25 Amps) in the LV using an irrigated focal catheter under intra-cardiac echocardiography (ICE) guidance for MB monitoring. Two control swine received air MBs through the lumen of the ablation catheter. Swine underwent brain MRI before and after PFA (or control air MB injection). Gross pathology and histology of brains with abnormal MRI findings were performed.

RESULTS

Four healthy and 5 chronic MI swine underwent 124 left ventricular PFA applications. No PFA-related MB formation was noted on ICE. Both control swine developed multiple acute emboli in the thalamus and caudate on DWI, ADC, and FLAIR brain MRI images in response to air MB injection. Of the 9 PFA swine, there were no abnormalities on ADC or FLAIR images. There was one hyperintense focus in the left putamen on the DWI trace image, but the absence of ADC or FLAIR affirmation suggested it was artifact. Gross pathology and histopathology of this region did not detect any abnormalities.

CONCLUSIONS

Focal monopolar biphasic PFA of both healthy and chronically infarcted left ventricular myocardium does not generate any MB or cerebral emboli observable on ICE and brain MRI.

Pearls and Pitfalls of Pulsed Field Ablation

Pulsed field ablation (PFA) was recently rediscovered as an emerging treatment modality for the ablation of cardiac arrhythmias. Ultra-short high voltage pulses are leading to irreversible electroporation of cardiac cells subsequently resulting in cell death. Current literature of PFA for pulmonary vein isolation (PVI) consistently reported excellent acute and long-term efficacy along with a very low adverse event rate. The undeniable benefit of the novel ablation technique is that cardiac cells are more susceptible to electrical fields whereas surrounding structures such as the pulmonary veins, the phrenic nerve or the esophagus are not, or if at all, minimally affected, which results in a favorable safety profile that is expected to be superior to the current standard of care without compromising efficacy. Nevertheless, the exact mechanisms of electroporation are not yet entirely understood on a cellular basis and pulsed electrical field protocols of different manufactures are not comparable among one another and require their own validation for each indication. Importantly, randomized controlled trials and comparative data to current standard of care modalities, such as radiofrequency- or cryoballoon ablation, are still missing. This review focuses on the "pearls" and "pitfalls" of PFA, a technology that has the potential to become the future leading energy source for PVI and beyond.

Pulsed-Field Ablation Using a Novel Ablation-Mapping Integrated System for Pulmonary Vein Isolation-A Preliminary Animal Study

OBJECTIVE

The purpose of this study is to evaluate the preliminary safety and effect of a pulsed electric field (PEF) ablation system.

METHODS

The pulmonary veins (PVs) and superior vena cava (SVC) were isolated with the pulsed field ablation (PFA) system, which included a PEF generator and an electrode. The effects of PFA were investigated in six porcines using a novel circular catheter with combined functions (mapping/ablation) designed to work with a cardiac mapping system. The PEF generator delivered a train of biphasic pulsed electric pulses with a high amplitude (800-2000 V) and short pulse duration. The voltage mapping, PVs and SVC potentials, ostial diameters, and phrenic nerve and esophagus viability data were collected 4 weeks later, after which the animals were subsequently euthanized for gross histopathology analysis.

RESULTS

PFA 100% isolated the PVs and SVC with four applications with a mean pulse number of 100-150 pulses, causing no muscle convulsion. PFA does not cause PV stenosis or phrenic nerve dysfunction. Histological analysis confirmed 100% transmurally without any venous stenoses or phrenic injuries. Pathology follow-up showed that PFA had selectively ablated cardiomyocytes but spared blood vessels, the esophagus, and phrenic nerves; after ablation, the myocardial tissue showed homogeneous fibrosis.

CONCLUSION

The PFA system is safe and feasible in the preliminary porcine model, which can effectively isolate PVs and SVCs. Transmural tissue damage can be achieved without phrenic palsy or stenosis.

Cerebral safety after pulsed field ablation for paroxysmal atrial fibrillation

BACKGROUND

Pulsed field ablation (PFA) is a novel, nonthermal ablation modality that can ablate myocardial tissue with minimal effects on surrounding tissue. Preclinical data show an absence of cerebral emboli after extensive PFA. However, clinical data on silent cerebral lesions (SCLs) and/or silent cerebral events (SCEs) after PFA are lacking.

OBJECTIVES

The purpose of this study was to investigate the occurrence of neurological deficits and SCL and/or SCE after PFA in paroxysmal atrial fibrillation (AF) using National Institutes of Health Stroke Scale (NIHSS) scores and magnetic resonance imaging (MRI).

METHODS

In patients with symptomatic paroxysmal AF, pulmonary vein isolation (PVI) using PFA was performed. NIHSS scores were assessed before and 2 days and 30 days after PVI. One day after PVI, patients underwent cerebral 1.5-T MRI scanning using diffusion-weighted imaging and fluid-attenuated inversion recovery sequences to document the occurrence of SCL/SCE.

RESULTS

PFA was performed in 30 patients (age 63 ± 10 years). No patient showed neurological deficits. All NIHSS scores showed the minimum value of 0. Cerebral MRI scans were normal in 29 of 30 patients (97%). In 1 patient (3%), a single 7-mm cerebellar lesion was observed. Forty days after the procedure, follow-up cerebral MRI scan showed complete regression of the lesion.

CONCLUSION

In patients treated with PFA for symptomatic paroxysmal AF, the incidence of MRI-detected asymptomatic thromboembolic cerebral events or lesions was as low as 3%. No neurological deficits occurred in any of the patients.

First experience with pulsed field ablation as routine treatment for paroxysmal atrial fibrillation

AIMS

Catheter ablation for atrial fibrillation (AF) using thermal energy can cause collateral damage. Pulsed field ablation (PFA) is a novel non-thermal energy source. Few small clinical studies have been published. We report on the first 'real-world' experience with pulmonary vein isolation (PVI) using PFA for paroxysmal AF (PAF).

METHODS AND RESULTS

Pre- and post-ablation, phrenic nerve function was assessed. After high-density left atrial (LA) bipolar voltage mapping, all PVs were individually isolated using a 13 Fr steerable sheath and a pentaspline PFA over-the-wire catheter. After ablation, bipolar voltage mapping was repeated to assess lesion formation. In 30 PAF patients (mean 63 years; 53% female), uncomplicated PFA was performed, with all PVs acutely isolated. The median procedure time was 116 min. The median PFA catheter LA dwell time was 29 min. The median fluoroscopy time was 26 min. In one patient with roof-dependent flutter, a roof line was intentionally created. In two patients, unintentional bidirectional mitral isthmus block was created. There was no phrenic nerve or oesophageal damage. In one patient, pericardial drainage after cardiac tamponade was performed. In-hospital stay and 30-day follow-up were uneventful. After 90 days, 97% of patients were in sinus rhythm.

CONCLUSION

PVI using PFA for PAF in a 'real-world' setting appears to be safe and feasible in this small patient cohort. Procedure times are homogeneous, and LA dwell time is short. Atrial ablation lines can easily be created. Unintentional ablation of atrial tissue can occur, accurate catheter alignment to the PV ostium and axis should be ensured.

Pulsed-Field Ablation: What Are the Unknowns and When Will They Cease to Concern Us?

Catheter ablation (CA) is the mainstay therapy for the maintenance of sinus rhythm in patients with paroxysmal and persistent atrial fibrillation (AF). This article is protected by copyright. All rights reserved.

[Pulsed field ablation : The ablation technique of the future?]

The ablation of cardiac arrhythmias is now standard therapy in invasive electrophysiology with a focus on atrial fibrillation due to its high prevalence. Thermal energy sources such as radiofrequency or cryoablation are the most commonly used techniques to date. Due to limitations in terms of effectiveness and safety because of possible indiscriminate tissue destruction, ablation using pulsed field ablation (PFA) can be a safe and effective alternative to thermal ablation techniques. This is a nonthermal form of energy that creates effective myocardial lesions by means of irreversible electroporation by generating short, high-energy electrical impulses. Preliminary data show high effectiveness with a low complication rate. Myocardial tissue shows a high specificity while sparing surrounding structures such as the esophagus, the phrenic nerve and surrounding vascular structures. Therefore, irreversible electroporation is a very promising technique and has the potential to become the perfect form of energy for many catheter ablations and especially for pulmonary vein isolation. In this article we provide an overview of the current status of PFA as well as an outlook on future fields of treatment.

Ablation Modalities for Therapeutic Intervention in Arrhythmia-Related Cardiovascular Disease: Focus on Electroporation

Targeted cellular ablation is being increasingly used in the treatment of arrhythmias and structural heart disease. Catheter-based ablation for atrial fibrillation (AF) is considered a safe and effective approach for patients who are medication refractory. Electroporation (EPo) employs electrical energy to disrupt cell membranes which has a minimally thermal effect. The nanopores that arise from EPo can be temporary or permanent. Reversible electroporation is transitory in nature and cell viability is maintained, whereas irreversible electroporation causes permanent pore formation, leading to loss of cellular homeostasis and cell death. Several studies report that EPo displays a degree of specificity in terms of the lethal threshold required to induce cell death in different tissues. However, significantly more research is required to scope the profile of EPo thresholds for specific cell types within complex tissues. Irreversible electroporation (IRE) as an ablative approach appears to overcome the significant negative effects associated with thermal based techniques, particularly collateral damage to surrounding structures. With further fine-tuning of parameters and longer and larger clinical trials, EPo may lead the way of adapting a safer and efficient ablation modality for the treatment of persistent AF.