Impact of Pulsed-Field Ablation on Intrinsic Cardiac Autonomic Nervous System After Pulmonary Vein Isolation

Prevalence, Timing, and Impact of Early Recurrence of Atrial Tachyarrhythmias after Pulsed Field Ablation: A Secondary Analysis of the PULSED AF Trial

BACKGROUND

Early recurrence of atrial tachyarrhythmias (ERATs) within three months following thermal ablation for atrial fibrillation (AF) is common and often considered transient. Pulsed field ablation (PFA) is a non-thermal energy source in which ERAT is not well described.

OBJECTIVE

To analyze ERAT in AF patients undergoing PFA in the PULSED AF trial.

METHODS

This analysis included 294 patients (154 paroxysmal, 140 persistent AF) that had ≥10 rhythm assessments during the 90-day blanking period. ERAT was defined as any instance of ≥30s of AF, atrial flutter, or atrial tachycardia on trans-telephonic monitoring (weekly and symptomatic) or ≥10s on ECG (at 3 months), both within 90 days. Late recurrence of atrial tachyarrhythmias (LRATs) was defined as observed atrial tachyarrhythmias between 90 days and 12 months.

RESULTS

The overall prevalence of ERAT was 27.1% in paroxysmal and 31.6% in persistent AF patients. In patients with ERAT, 73% had ERAT onset within the first month post-procedure. Presence of ERAT was associated with LRAT in paroxysmal (HR 6.4 (95% c.i. 3.6-11.3)) and persistent (HR 3.8 (95% c.i. 2.2-6.6)) AF patients. Yet, in 29.4% of paroxysmal and 34.3% of persistent AF patients with ERAT, LRAT was not observed. LRAT was positively correlated with the number of ERAT observations.

CONCLUSION

ERAT post PFA predicted LRAT in paroxysmal and persistent AF patients. However, the concept of a blanking period post PFA is still valid as approximately 1/3 of patients with ERAT did not continue on to LRAT during follow-up and may not need re-ablation.

State-of-the-art pulsed field ablation for cardiac arrhythmias: ongoing evolution and future perspective

Pulsed field ablation (PFA) is an innovative approach in the field of cardiac electrophysiology aimed at treating cardiac arrhythmias. Unlike traditional catheter ablation energies, which use radiofrequency or cryothermal energy to create lesions in the heart, PFA utilizes pulsed electric fields to induce irreversible electroporation, leading to targeted tissue destruction. This state-of-the-art review summarizes biophysical principles and clinical applications of PFA, highlighting its potential advantages over conventional ablation methods. Clinical data of contemporary PFA devices are discussed, which combine predictable procedural outcomes and a reduced risk of thermal collateral damage. Overall, these technological developments have propelled the rapid evolution of contemporary PFA catheters, with future advancements potentially impacting patient care.

Initial real-world data on catheter ablation in patients with persistent atrial fibrillation using the novel lattice-tip focal pulsed-field ablation catheter

AIMS

Technological advancements have contributed to the enhanced precision and lesion flexibility in pulsed-field ablation (PFA) by integrating a three-dimensional mapping system combined with a point-by-point ablation strategy. Data regarding the feasibility of this technology remain limited to some clinical trials. This study aims to elucidate initial real-world data on catheter ablation utilizing a lattice-tip focal PFA/radiofrequency ablation (RFA) catheter in patients with persistent atrial fibrillation (AF).

METHODS AND RESULTS

Consecutive patients who underwent catheter ablation for persistent AF via the lattice-tip PFA/RFA catheter were enrolled. We evaluated acute procedural data including periprocedural data as well as the clinical follow-up within a 90-day blanking period. In total, 28 patients with persistent AF underwent AF ablation either under general anaesthesia (n = 6) or deep sedation (n = 22). In all patients, pulmonary vein isolation was successfully achieved. Additional linear ablations were conducted in 21 patients (78%) with a combination of successful anterior line (n = 13, 46%) and roof line (n = 19, 68%). The median procedural and fluoroscopic times were 97 (interquartile range, IQR: 80-114) min and 8.5 (IQR: 7.2-9.5) min, respectively. A total of 27 patients (96%) were interviewed during the follow-up within the blanking period, and early recurrent AF was documented in four patients (15%) including one case of recurrent AF during the hospital stay. Neither major nor minor procedural complication occurred.

CONCLUSION

In terms of real-world data, our data confirmed AF ablation feasibility utilizing the lattice-tip focal PFA/RFA catheter in patients with persistent AF.

Recurrences after Pulsed Field Ablation of Atrial Fibrillation: Incidence, Mechanisms, Predictors, and Comparison with Thermal Energy

Pulsed Field Ablation (PFA) is the latest and most intriguing technology for catheter ablation of atrial fibrillation, due to its capability to generate irreversible and cardiomyocytes-selective electroporation of cell membranes by delivering microsecond-lasting high-voltage electrical fields, leading to high expectations. The first trials to assess the clinical success of PFA, reported an arrhythmia-free survival at 1-year of 78.5%, while other trials showed less enthusiastic results: 66.2% in paroxysmal and 55.1% in persistent AF. Nevertheless, real world data are encouraging. The isolation of pulmonary veins with PFA is easily achieved with 100% acute success. Systematic invasive remapping showed a high prevalence of durable pulmonary vein isolation at 75 and 90 days (range 84-96%), which were significatively lower in redo procedures (64.3%). The advent of PFA is prompting a reconsideration of the role of the autonomic nervous system in AF ablation, as PFA-related sparing of the ganglionated plexi could lead to the still undetermined effect on late arrhythmias' recurrences. Moreover, a new concept of a blanking period could be formulated with PFA, according to its different mechanism of myocardial injury, with less inflammation and less chronic fibrosis. Finally, in this review, we also compare PFA with thermal energy.

Initial clinical experience with the balloon-in-basket pulsed field ablation system: acute results of the VOLT CE mark feasibility study

AIMS

Pulsed field ablation (PFA) for the treatment of atrial fibrillation (AF) potentially offers improved safety and procedural efficiencies compared with thermal ablation. Opportunities remain to improve effective circumferential lesion delivery, safety, and workflow of first-generation PFA systems. In this study, we aim to evaluate the initial clinical experience with a balloon-in-basket, 3D integrated PFA system with a purpose-built form factor for pulmonary vein (PV) isolation.

METHODS AND RESULTS

The VOLT CE Mark Study is a pre-market, prospective, multi-centre, single-arm study to evaluate the safety and effectiveness of the Volt™ PFA system for the treatment of paroxysmal (PAF) or persistent AF (PersAF). Feasibility sub-study subjects underwent phrenic nerve evaluation, endoscopy, chest computed tomography, and cerebral magnetic resonance imaging. Study endpoints were the rate of primary serious adverse event within 7 days and acute procedural effectiveness. A total of 32 subjects (age 61.6 ± 9.6 years, 65.6% male, 84.4% PAF) were enrolled and treated in the feasibility sub-study and completed a 30-day follow-up. Acute effectiveness was achieved in 99.2% (127/128) of treated PVs (96.9% of subjects, 31/32) with 23.8 ± 4.2 PFA applications/subject. Procedure, fluoroscopy, LA dwell, and transpired ablation times were 124.6 ± 28.1, 19.8 ± 8.9, 53.0 ± 21.0, and 48.0 ± 19.9 min, respectively. Systematic assessments of initial safety revealed no phrenic nerve injury, pulmonary vein stenosis, or oesophageal lesions causally related to the PFA system and three subjects with silent cerebral lesions (9.4%). There were no primary serious adverse events.

CONCLUSION

The initial clinical use of the Volt PFA System demonstrates acute safety and effectiveness in the treatment of symptomatic, drug refractory AF.

Meta-analysis of pulsed-field ablation versus cryoablation for atrial fibrillation

PURPOSE

The available data on the treatment strategy of pulsed field ablation (PFA) for patients with atrial fibrillation (AF) is limited. This study aims to provide a comparative analysis of the efficacy, safety, and procedural efficiency between PFA and cryoballoon ablation (CBA) for AF.

METHODS

We conducted a comprehensive search of the EMBASE, PubMed, Cochrane Library, and ClinicalTrials.gov databases to identify trials comparing PFA with CBA for AF from their inception until December 2023. The odds ratio (OR) and mean difference (MD), along with a 95% confidence interval (CI), were utilized as measures of treatment effect.

RESULTS

The analysis included 15 eligible trials with a total enrollment of 1880 patients. No significant differences were found in recurrent atrial arrhythmia (OR 0.83, 95% CI 0.64, 1.07) or periprocedural complications (OR 0.78, 95% CI 0.46, 1.30) between the two ablation techniques examined in this study. However, the PFA technique demonstrated a significantly shorter procedure time (MD -7.17, 95% CI -13.60, -0.73), but a longer fluoroscopy time (MD 2.53, 95% CI 0.87, 4.19). Similarly, PFA was found to be significantly associated with a decreased incidence of phrenic nerve palsy (OR 0.20, 95% CI 0.07, 0.59), but an increased incidence of cardiac tamponade (OR 4.07, 95% CI 1.15, 14.39). Moreover, there was a significantly higher release of troponin with PFA compared to CBA (MD 470.28, 95% CI 18.89, 921.67), while the increase in S100 protein and heart rate was significantly lower with PFA than with CBA (MD -64.41, 95% CI -105.46, -17.36), (MD -8.76, 95% CI -15.12, -2.40).

CONCLUSION

The utilization of PFA provides a safer, time-saving, and tissue-specific procedure compared to CBA, while maintaining comparable success rates. This has the potential to enhance procedural efficiency and optimize resource utilization in clinical practice. These findings underscore the feasibility and promise of PFA as an alternative technique for PVI in patients with AF.

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.

The Effects of Interphase and Interpulse Delays and Pulse Widths on Induced Muscle Contractions, Pain and Therapeutic Efficacy in Electroporation-Based Therapies

Electroporation is used in medicine for drug and gene delivery, and as a nonthermal ablation method in tumor treatment and cardiac ablation. Electroporation involves delivering high-voltage electric pulses to target tissue; however, this can cause effects beyond the intended target tissue like nerve stimulation, muscle contractions and pain, requiring use of sedatives or anesthetics. It was previously shown that adjusting pulse parameters may mitigate some of these effects, but not how these adjustments would affect electroporation's efficacy. We investigated the effect of varying pulse parameters such as interphase and interpulse delay while keeping the duration and number of pulses constant on nerve stimulation, muscle contraction and assessing pain and electroporation efficacy, conducting experiments on human volunteers, tissue samples and cell lines in vitro. Our results show that using specific pulse parameters, particularly short high-frequency biphasic pulses with short interphase and long interpulse delays, reduces muscle contractions and pain sensations in healthy individuals. Higher stimulation thresholds were also observed in experiments on isolated swine phrenic nerves and human esophagus tissues. However, changes in the interphase and interpulse delays did not affect the cell permeability and survival, suggesting that modifying the pulse parameters could minimize adverse effects while preserving therapeutic goals in electroporation.

Efficacy and safety of pulmonary vein isolation with pulsed field ablation vs. novel cryoballoon ablation system for atrial fibrillation

AIMS

Pulsed-field ablation (PFA) has emerged as a novel treatment technology for patients with atrial fibrillation (AF). Cryoballoon (CB) is the most frequently used single shot technology. A direct comparison to a novel CB system is lacking. We aimed to compare pulmonary vein isolation (PVI) using PFA vs. a novel CB system regarding efficiency, safety, myocardial injury, and outcomes.

METHODS AND RESULTS

One hundred and eighty-one consecutive patients underwent PVI and were included (age 64 ± 9.7 years, ejection fraction 0.58 ± 0.09, left atrial size 40 ± 6.4 mm, paroxysmal AF 64%). 106 patients (59%) underwent PFA (FARAPULSE, Boston Scientific) and 75 patients (41%) underwent CB ablation (PolarX, Boston Scientific). The median procedure time, left atrial dwell time and fluoroscopic time were similar between the PFA and the CB group with 55 [interquartile range (IQR) 43-64] min vs. 58 (IQR 48-69) min (P < 0.087), 38 (30-49) min vs. 37 (31-48) min, (P = 0.871), and 11 (IQR 9.3-14) min vs. 11 (IQR 8.7-16) min, (P < 0.81), respectively. Three procedural complications were observed in the PFA group (two tamponades, one temporary ST elevation) and three complications in the CB group (3× reversible phrenic nerve palsies). During the median follow-up of 404 days (IQR 208-560), AF recurrence was similar in the PFA group and the CB group with 24 vs. 30%, P = 0.406.

CONCLUSION

Procedural characteristics were very similar between PFA and CB in regard to procedure duration fluoroscopy time and complications. Atrial fibrillation free survival did not differ between the PFA and CB groups.

Early recurrences predict late therapy failure after pulsed field ablation of atrial fibrillation

INTRODUCTION

Pulsed field ablation (PFA) is a new ablation technology for atrial fibrillation (AF). Data regarding early recurrences of atrial tachyarrhythmia (ERAT) after PFA-pulmonary vein isolation (PVI) are sparse.

METHODS

Consecutive patients with symptomatic AF were enrolled to undergo PFA-PVI. A dedicated catheter delivering bipolar energy (1.9-2.0 kV) was used. Late recurrence (LR) was defined as documented AF/atrial tachycardia (AT) lasting more than 30 s after a 90-day blanking period.

RESULTS

Two hundred and thirty-one patients (42% female, age 69 ± 12, 55% paroxysmal AF [PAF]) were included in this analysis. Median follow-up time was 367 days (interquartile range: 253-400). Forty-six patients (21%) experienced ERAT after a median of 23 days (46% in PAF and 54% in persistent AF [persAF]). Kaplan-Meier estimated freedom of AF/AT was 74.2% at 1 year, 81.8% for PAF, and 64.8% for persAF (p = .0079). Of patients experiencing ERAT, an LR was observed in 54%. There was no significant difference of LR between those who presented with very early ERAT (0-45 days) and those with ERAT (46-90 days) (p = .57). In multivariate analysis, ERAT (hazard ratio [HR]: 3.370; 95% confidence interval [95% CI]: 1.851-6.136; p < .001) and female sex (HR: 2.048; 95% CI: 1.114-3.768; p = .021) were the only independent predictors for LR.

CONCLUSIONS

ERAT could be recorded in 21% of patients after PFA-PVI and was an independent predictor for LR. We found no difference in the rate of LRs among patients experiencing ERAT before or after 45 days.

Pulsed field ablation for atrial fibrillation - Lessons from magnetic resonance imaging

Pulsed field ablation (PFA) is a promising technology for the treatment of atrial fibrillation (AF). Due to its unique tissue selectivity, PFA potentially bears superior characteristics as compared to established thermal energy sources in AF ablation procedures. Cardiovascular magnetic resonance imaging (CMR) using late gadolinium enhancement (LGE) is an established tool in the analysis of myocardial fibrosis representing atrial cardiomyopathy as well as ablation-induced atrial scar formation following catheter ablation with thermal energy. Mechanisms of atrial lesion formation differ between thermal ablation and electroporation and its impact on results of CMR imaging are not fully understood until now. In this review article, the potential of CMR imaging for PFA lesion assessment and available data are discussed. Further, additional needs to adopt imaging approaches to the cellular mechanisms of electroporation are considered.