Thermal Profiles for Focal Pulsed Electric Field Ablation

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.

Mechanisms of action behind the protective effects of proactive esophageal cooling during radiofrequency catheter ablation in the left atrium

Proactive esophageal cooling for the purpose of reducing the likelihood of ablation-related esophageal injury resulting from radiofrequency (RF) cardiac ablation procedures is increasingly being used and has been Food and Drug Administration cleared as a protective strategy during left atrial RF ablation for the treatment of atrial fibrillation. In this review, we examine the evidence supporting the use of proactive esophageal cooling and the potential mechanisms of action that reduce the likelihood of atrioesophageal fistula (AEF) formation. Although the pathophysiology behind AEF formation after thermal injury from RF ablation is not well studied, a robust literature on fistula formation in other conditions (eg, Crohn disease, cancer, and trauma) exists and the relationship to AEF formation is investigated in this review. Likewise, we examine the abundant data in the surgical literature on burn and thermal injury progression as well as the acute and chronic mitigating effects of cooling. We discuss the relationship of these data and maladaptive healing mechanisms to the well-recognized postablation pathophysiological effects after RF ablation. Finally, we review additional important considerations such as patient selection, clinical workflow, and implementation strategies for proactive esophageal cooling.

Efficacy and safety of pulsed field ablation compared to cryoballoon ablation in the treatment of atrial fibrillation: a meta-analysis

Aims

Pulmonary vein isolation (PVI) represents the gold standard in the treatment of atrial fibrillation (AF) and the use of single-shot techniques, such as cryoballoon ablation (CBA) and pulsed field ablation (PFA) using a pentaspline catheter, has gained prominence. Recent studies hypothesize that PFA might be superior to CBA, although procedural efficacy and safety data are inconsistent. A meta-analysis was conducted to compare both energy sources for the treatment of AF.

Methods and results

A structured systematic database search and meta-analysis were performed on studies investigating outcomes, periprocedural complications, and/or procedural parameters of AF patients treated by either CBA or PFA. Eleven studies reporting data from 3805 patients were included. Pulmonary vein isolation by PFA was associated with a significantly lower recurrence of atrial fibrillation/atrial tachycardia [odds ratio (OR) = 0.73, 95% confidence interval (CI) = 0.54-0.98, I2 = 20%] and fewer periprocedural complications (OR = 0.62, 95% CI = 0.40-0.96, I2 = 6%) compared to CBA. The lower complication rate following PFA was mainly driven by fewer phrenic nerve injuries (OR = 0.19, 95% CI = 0.08-0.43, I2 = 0%). However, there were more cases of cardiac tamponades after PFA (OR = 2.56, 95% CI = 1.01-6.49, I2 = 0%). Additionally, using PFA for PVI was associated with shorter total procedure times [mean difference (MD) = -9.68, 95% CI = -14.92 to -4.43 min, I2 = 92%] and lower radiation exposure (MD = -148.07, 95% CI = -276.50 to -19.64 µGy·mI2 = 7%).

Conclusion

Our results suggest that PFA for PVI, compared to CBA, enables shorter procedure times with lower arrhythmia recurrence and a reduced risk of periprocedural complications. Randomized controlled trials need to confirm our findings.

Pulsed-field ablation does not induce esophageal and periesophageal injury-A new esophageal safety paradigm in catheter ablation of atrial fibrillation

INTRODUCTION

Esophageal injury is one of the most serious complications of pulmonary vein isolation (PVI) with thermic energy sources. Better tissue selectivity of primarily non-thermic pulsed field ablation (PFA) may eliminate collateral injury, particularly the risk of atrio-esophageal fistula (AEF).

OBJECTIVE

To compare the incidence of any (peri)-esophageal injury following PVI using PFA to thermic energy sources.

METHODS

Using endoscopy, endoscopic ultrasound, and electrogastrography before and after PVI, esophageal and periesophageal injury (mucosal lesions, food retention, periesophageal edema, or vagal nerve injury) were assessed following PFA and radiofrequency (RF)- or cryoballoon (CB)-PVI.

RESULTS

Between December 2022 and February 2023, 20 patients (67 ± 10 years, 53% male) undergoing PFA (Farapulse, Boston Scientific) for atrial fibrillation (AF) were studied and compared with a previous cohort of 57 patients who underwent thermic PVI (CB: n = 33; RF: n = 24). Following PFA-PVI, none of the patients had mucosal lesions, food retention, or ablation-induced vagal nerve injury; four patients showed periesophageal edema. Following thermic ablation, 33/57 patients (58%) showed esophageal and/or periesophageal injury (CB: 21/33 [64%], RF: 12/24 [50%]), in detail 4/57 mucosal lesions, 18/57 food retention, 17/57 vagal nerve injury, and 20/52 edema. Midterm success rates were similar for all energy sources.

CONCLUSION

In contrast to thermic ablation tools, PFA is not associated with relevant esophageal and periesophageal injury, and might, therefore, reduce or eliminate the risk of potentially lethal AEF in interventional treatment of AF. The etiology of ablation-induced periesophageal edema is unknown but has not been shown to be related to lesion progression.

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.

A real-world case-control study on the efficacy and safety of pulsed field ablation for atrial fibrillation

OBJECTIVE

The primary objective of this study was to evaluate the efficacy and safety of pulsed field ablation in individuals diagnosed with atrial fibrillation.

METHODS

A total of 36 patients diagnosed with atrial fibrillation were enrolled in the pulsed field ablation group, while another 36 patients diagnosed with atrial fibrillation were included in the radiofrequency ablation group. Among the study participants, 15 patients in the pulsed field ablation group and 17 patients in the radiofrequency ablation group had persistent atrial fibrillation. Comprehensive comparisons were made between the two groups, including baseline data, underlying diseases, medication usage, intraoperative parameters, and atrial fibrillation recurrence rates at 1, 3, and 6 months during the postoperative follow-up period.

RESULTS

(1) There were no significant differences observed between the two groups concerning baseline data and antiarrhythmic drug usage (P > 0.05); (2) the effective ablation time for both left and right pulmonary veins in the pulsed field ablation group was markedly shorter compared to the radiofrequency ablation group (P < 0.001 for each vein); (3) within the pulsed field ablation group, the number of discharges, catheter operation time, and effective ablation time for the left pulmonary vein were significantly higher than those for the right pulmonary vein (P < 0.05). Conversely, in the radiofrequency ablation group, the number of discharges for the left pulmonary vein was significantly higher than that for the right pulmonary vein (P < 0.05); and (4) when comparing sinus rhythm maintenance at 1, 3, and 6 months postoperatively, no statistically significant differences were noted between the two groups for paroxysmal, persistent, and paroxysmal + persistent atrial fibrillation cases (P > 0.05).

CONCLUSION

During the 6-month follow-up period, pulsed field ablation demonstrated comparable efficacy to radiofrequency ablation with respect to recurrence rates for both paroxysmal and persistent atrial fibrillation. Moreover, pulsed field ablation exhibited high safety levels, excellent surgical efficiency, and a notably brief learning curve, affirming its viability as a therapeutic option for these conditions.