Pulsed field ablation prevents chronic atrial fibrotic changes and restrictive mechanics after catheter ablation for atrial fibrillation

Impact of radiofrequency versus cryoballoon ablation on left atrial calcification after atrial fibrillation ablation: A propensity score-matched comparison

INTRODUCTION

Left atrial calcification (LAC) following atrial fibrillation (AF) ablation is associated with major adverse cardiovascular events, with prior reports focusing on radiofrequency catheter ablation (RFCA) rather than cryoballoon ablation (CBA). The aim of this study was to investigate the frequency of LAC and stiff LA physiology (SLAP) in patients undergoing CBA as the initial therapy for AF, compared with those undergoing RFCA, using a propensity score-matched (PSM) population.

METHODS

We conducted a retrospective cohort study involving 2680 consecutive patients who underwent AF ablation with RFCA or CBA. Patients with rheumatic valve disease or mitral valve replacement, those undergoing dialysis, and those without postoperative computed tomography (CT) imaging were excluded. CT images acquired ≥1 year after the initial procedure were used to evaluate the LAC.

RESULTS

In total, 473 eligible patients were identified. PSM created 125 pairs. After a median follow-up of 4.7 years, 9 (4 %) of 250 patients presented with LAC. Those who underwent CBA had a significantly lower incidence of LAC and SLAP compared to those who underwent RFCA (LAC: 1 % vs. 6 %, P = 0.03; SLAP: 1 % vs. 9 %, P = 0.005). Right ventricular systolic pressure significantly increased in the RFCA group (pre-ablation: 23 ± 8 vs. post-ablation: 26 ± 8, P = 0.01), but remained unchanged in the CBA group (pre-ablation: 23 ± 7 vs. post-ablation: 23 ± 8, P = 0.88).

CONCLUSIONS

The use of CBA as the initial ablation seems to have clinical benefits in preventing LAC and SLAP compared to RFCA.

Lesion Characteristics of Pulsed Field Ablation

Pulsed field ablation (PFA) has emerged as a promising, nonthermal technique for arrhythmia ablation, leveraging high-voltage electrical fields to induce electroporation and create precise ablation lesions. Unlike traditional thermal methods such as radiofrequency ablation (RFA) and cryoablation, PFA selectively targets myocardial cells while sparing surrounding tissues, reducing the risk of collateral damage. This review focuses on the key characteristics of PFA lesion formation, drawing comparisons with RFA and cryoablation based on histopathology, imaging, and electroanatomical mapping.

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

Background

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

Case summary

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

Conclusion

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

Safety and effectiveness of pulsed field ablation for pulmonary vein isolation in atrial fibrillation patients: One-year single center experience

INTRODUCTION AND OBJECTIVES

Pulmonary vein (PV) isolation is one of the cornerstones of rhythm-control therapy for symptomatic atrial fibrillation (AF) patients. Pulsed field ablation (PFA) is a novel ablation modality that involves the application of electrical pulses causing cellular death, and it has preferential tissue specificity. In this study, we aimed to share a one-year single center experience of AF ablation with PFA.

METHODS

Single center, retrospective study of consecutive patients undergoing PVI using the pentaspline PFA catheter between June 2022 and July 2023. Data on demographic, procedural, and electrocardiographic recurrence (assessed after a three-month blanking period) were analyzed.

RESULTS

One hundred twenty-three consecutive patients were included (62±11 years, 59% male), with a mean CHA2DS2-VASc score of 2±1 points, median left ventricular ejection fraction of 61% [IQR 60-65%] and a median left atrial volume index (by CT scan) of 55 mL/m2 [IQR 41-67 mL/m2]. Fifty-two percent of patients presented paroxysmal AF and 21 patients (17%) underwent a redo ablation. Median procedure time was 83 min [IQR 59-117 min] and median fluoroscopy time was 11.6 min [IQR 8.2-15.6 min]; posterior wall isolation was performed in 43 (35%). Two patients (1.6%) experienced acute cardiac tamponade, immediately treated with pericardiocentesis. Other complications were primarily vascular, in 4% of cases (three femoral hematomas, one femoral pseudoaneurysms, one arteriovenous fistula). Over 290 (IQR 169-387) days of follow-up, considering electrocardiographic recurrence beyond the blanking period, 9% of patients had AF recurrence (two with paroxysmal AF and nine with persistent AF).

CONCLUSIONS

Pulsed field ablation for PVI and posterior wall ablation was an efficient and safe procedure with low rate of complications and high percentage of patients were free from AF in short-term follow-up. We need more studies to evaluate long-term success.

NEMESIS-PFA: Investigating Collateral Tissue Injury Associated With Pulsed Field Ablation

BACKGROUND

Early evidence showed reduced complications with pulsed field ablation (PFA), but non-target tissue collateral damage created by electroporation effects is poorly understood and may significantly differ between systems.

OBJECTIVES

In this study, the authors evaluated the collateral effects of PFA.

METHODS

NEMESIS-PFA is a multicenter, observational registry of patients who underwent AF ablation from March 2024 onwards with any approved PFA systems-either a circular multielectrode array, spherical, pentaspline, or variable loop catheter-or radiofrequency ablation (RFA). We assessed procedural characteristics, biomarkers for myocardial injury, hemolytic anemia, and renal function, and left atrial function in select patients.

RESULTS

A total of 871 patients, aged 68.9 ± 10.9 years and male (70.8%), with paroxysmal atrial fibrillation (59.4%), and CHA2DS2VASC of 3.3 ± 1.3 were included. Of these, 87.1% (n = 773) underwent PFA with a pentaspline (70.9%), circular multielectrode (14.1%), spherical (12.4%), and variable loop (2.3%) catheter. Significant postprocedural change in certain biomarkers such as troponin (13,551.0 vs 127.5 ng/dL; P < 0.001), lactate dehydrogenase (107.5 vs 26.5 IU/L; P < 0.001), and haptoglobin (-102.0 vs -33.5 mg/dL; P < 0.001) were detected following the PFA procedures compared with RFA, and the change was dose-dependent. There were also significant differences in biomarkers across PFA systems. Lastly, there was a significant change in left atrial ejection fraction (-20.0% vs. -5.0%, P < 0.001) in PFA vs RFA.

CONCLUSIONS

Current PFA technologies are associated with worse troponin leak, hemolysis, and renal dysfunction than RFA. As PFA becomes mainstream, future studies appraising these effects and understanding the short term and long-term implications are needed.

Combined Catheter Ablation and Left Atrial Appendage Occlusion in Atrial Fibrillation: From Data to Clinical Reality

PURPOSE

Atrial fibrillation (AF) requires treatment that focuses on two main goals: symptom control and prevention of thromboembolic events. Catheter ablation and left atrial appendage occlusion (LAAO) constitute two well-established treatment methods in selected patients that accomplish these two goals correspondingly. Recently, there is increasing interest in performing the two procedures concomitantly in a so-called "combined" or "one-stop" procedure. This review aims to summarize the current data on the combined procedure, from the rationale and the techniques to its clinical efficacy, indications and future directions.

METHODS

An extensive search has been conducted using the MEDLINE/PubMed database to identify the relevant studies.

RESULTS

The reported success rates of the combined procedure are very high and frequently reach 100% when performed by experienced operators. The periprocedural and follow-up complications are low, the procedure is cost-effective, while there is significant stroke, bleeding and arrhythmia incidence reduction that does not seem to be undermined by interference between the two interventions. There are also a few indications that the one-stop procedure has a positive effect on left atrial mechanical function as it has been correlated with left atrial reverse remodeling. On the other hand, some studies suggest possible increase in peri-device leaks (PDLs), compared with LAAO alone, which could in turn negatively affect the clinical outcomes. Most available studies are small and observational, with a lack of randomized controlled trials.

CONCLUSION

Catheter ablation and left atrial appendage occlusion can be safely and effectively combined in a cost-effective single procedure in carefully selected patients.

Pulsed-field ablation versus radiofrequency or cryoballoon thermal ablation in atrial fibrillation: a systematic review and meta-analysis

This review investigated efficacy and safety of pulsed-field ablation (PFA) in comparison with radiofrequency ablation (RFA), cryoballoon ablation (CBA), or both combined. The Odds ratio (OR) and mean difference (MD) with 95% confidence interval (95% CI) were computed. PFA allowed shorter procedure (MD -44.27 minutes, 95% CI: -63.61; -24.93) and left atrium (LA) dwell (MD -32.71 minutes (95% CI: -58.64; -6.78) times, but with longer fluoroscopy time than RFA (MD 8.54 minutes, 95% CI: 4.03; 13.04). Post-procedural complications rate was lower with PFA than CBA (OR 0.53, 95% CI: 0.35, 0.80). Atrial arrhythmias recurrence rate within one year of follow-up was lower with PFA than RFA (OR 0.68, 95% CI; 0.53; 0.87) and CBA (OR 0.69, 95% CI: 0.48; 0.97). PFA allowed shorter procedure and LA dwell times, as well as lower atrial arrhythmia recurrence than RFA and lower post-procedural complications and atrial arrhythmias recurrence rates than CBA.

Ablation of Ventricular and Atrial Arrhythmias in the Era of Cardiac Magnetic Resonance

In the past decade, cardiac magnetic resonance (CMR) has undergone remarkable progress, emerging as a pivotal tool in various cardiological scenarios. Its capacity for tissue characterization, both with and without contrast agents, makes CMR the perfect tool to study the substrate of arrhythmia. This review highlights the potential role of CMR in electrophysiology (EP) and its role in the ablation of atrial and ventricular arrhythmias. First, we will discuss the key aspects of ventricular arrhythmia ablation, while in the second part, we will review how CMR is changing the ablation of atrial arrhythmias. The potentiality of CMR in the pre-procedural, intra-procedural, and post-ablation assessment will be reviewed. In particular, CMR is capable of visualizing fibrosis and building 3D reconstruction. Furthermore, it is possible to merge a 3D-rendered shell of the heart into the EP room to guide radiation-free ablation through active or passive tracking. Finally, the accuracy of CMR in depicting ablation lesions and its ability to predict arrhythmia relapses will be discussed.

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 (ERAT) within 3 months of thermal ablation for atrial fibrillation (AF) is common and often considered transient. Pulsed field ablation (PFA) is a nonthermal energy source in which ERAT is not well described.

OBJECTIVE

The purpose of this study was to analyze ERAT in patients with AF undergoing PFA in the Pulsed Field Ablation to Irreversibly Electroporate Tissue and Treat AF (PULSED AF) trial.

METHODS

This analysis included 154 (52.4%) paroxysmal AF and 140 (47.6%) persistent AF who had ≥10 rhythm assessments during the 90-day blanking period. ERAT was defined as any instance of ≥30 seconds of AF, atrial flutter, or atrial tachycardia on transtelephonic monitoring (weekly and symptomatic) or ≥10 seconds on electrocardiography (at 3 months), both within 90 days. Late recurrence of atrial tachyarrhythmias (LRAT) was defined as observed atrial tachyarrhythmias between 90 days and 12 months.

RESULTS

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

CONCLUSION

ERAT after PFA predicted LRAT in patients with paroxysmal and persistent AF. However, the concept of a blanking period after PFA is still valid, as approximately one-third of patients with ERAT did not continue to have LRAT during follow-up and may not need reablation.

Combined pulsed field ablation and left atrial appendage occlusion: A multicenter comparative study

BACKGROUND

Combining pulsed field ablation (PFA) and left atrial appendage occlusion (LAAO) to 1 procedure is appealing for the treatment of atrial fibrillation.

OBJECTIVE

This study aimed to compare the outcome of combined and standalone procedures.

METHODS

This is a retrospective cohort study of consecutive patients undergoing combined PFA and LAAO procedures in 3 centers in 2023. They underwent PFA pulmonary vein isolation (PVI) with Farapulse (Boston Scientific, Marlborough, MA), followed by LAAO with WATCHMAN FLX (Boston Scientific) guided by transesophageal echocardiogram (TEE). Pulmonary ridge thickness was measured at 45 degrees, 5 mm from tip of the ridge, before and after PFA. At 3 months, TEE or computed tomography was performed for patients with LAAO to assess occlusion results. Peridevice leak (PDL) of more than 3 mm was defined as significant. Consecutive PFA or LAAO standalone procedures served as controls.

RESULTS

This cohort included 36 combined, 48 standalone LAAO, and 52 standalone PFA cases. Acute PVI was achieved in all combined and PFA standalone procedures. Successful LAAO implantation with WATCHMAN FLX was achieved in 97.2% combined procedures and all standalone LAAO procedures. In the combined cohort, pulmonary ridge thickness increased after ablation by 2.72 ± 1.19 mm (P < .001) or 69.4% ± 51.4%. At 3 months, the rate of PDL did not differ between combined and standalone LAAO cohorts (26.7 vs 15.2%, P = .22). However, significant PDL (> 3 mm) occurred more commonly in the combined cohort compared with the standalone LAAO cohort (20% vs 2.2%, P = .013).

CONCLUSION

Combined PFA and LAAO was feasible. However, we observed a mean 69.4% increase in pulmonary ridge thickness immediately following PFA. Significant PDL was more prevalent in combined procedure.

Pulsed-Field vs Thermal Catheter Ablation of Atrial Fibrillation in Patients With Hypertrophic Cardiomyopathy

BACKGROUND

Pulsed-field ablation (PFA) may be beneficial for the treatment of atrial fibrillation (AF) in patients with hypertrophic cardiomyopathy (HCM).

OBJECTIVES

The goal of this study was to compare the safety and efficacy of PFA and thermal ablation in patients with HCM and AF.

METHODS

From 2016 to 2024, patients with HCM undergoing a first AF ablation using PFA or thermal ablation (cryoballoon or radiofrequency) were retrospectively included from 3 French and Swiss centers. Freedom from atrial arrhythmia (AA) recurrence at the 12-month follow-up was assessed.

RESULTS

Overall, 109 patients (median age 60 years; 68% male; 43% paroxysmal AF) with HCM underwent PFA (n = 58) or thermal ablation (n = 51) of AF. In addition to pulmonary vein (PV) isolation, extra-PV ablation was performed in 62% of PFA cases and in 18% of thermal cases. PFA was associated with shorter median procedure times than thermal ablation (81 minutes [Q1-Q3: 60-110 minutes] vs 132 minutes [Q1-Q3: 75-190 minutes]; P < 0.0001) and with less postprocedural heart failure (n = 0 vs n = 4; P = 0.03). Freedom from AA recurrence was 57% (95% CI: 46%-67%) after 12 months. PFA was associated with less AA recurrence than thermal ablation (adjusted HR: 0.46; 95% CI: 0.23-0.91; P = 0.03). Extra-PV ablation was associated with more sustained AA recurrence with thermal ablation (HR: 3.07; 95% CI: 1.21-7.82; P = 0.02) but not with PFA (HR: 1.07; 95% CI: 0.35-3.27; P = 0.91).

CONCLUSIONS

In patients with HCM and AF, PFA seems to be associated with better safety and efficacy outcomes than thermal ablation.

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.

Effectiveness and Safety of Pulsed Field Ablation in Patients With Atrial Fibrillation

BACKGROUND

As a competitive nonthermal energy technique used in atrial fibrillation (AF), the effectiveness and safety of pulsed field ablation (PFA) has remained uncertain.

OBJECTIVES

The authors meta-analysis aimed to investigate the effectiveness and safety of PFA in treating AF patients and compare its outcomes with conventional thermal ablation.

METHODS

The PubMed, Embase, and Cochrane Library databases were systematically searched until January 2024 for relevant studies investigating the use of PFA for AF. A fixed-effects model was used for pooled analysis if the I2 value was <50%; otherwise, a random-effects model was applied.

RESULTS

A total of 46 studies were included in this analysis. The single-arm meta-analysis of 40 studies showed an acute pulmonary vein isolation (PVI) rate of 99.79% per pulmonary vein (PV) and 99.47% per patient, with atrial arrhythmia recurrence rates of 12.36%, 12.42%, and 23.28% at 3, 6, and 12 months, respectively. The safety outcomes incidence was low. In the comparison of 21 studies between PFA and thermal ablation, PFA demonstrated comparable acute PVI rates but a higher first-pass isolation rate. PFA was associated with a lower incidence of atrial arrhythmia recurrence after 3 months and phrenic nerve paralysis or injury, but a higher risk of cardiac perforation or tamponade. Procedure time was shorter with PFA.

CONCLUSIONS

PFA showed noninferiority to thermal ablation in acute PVI and superiority in first-pass isolation, atrial arrhythmia recurrence, phrenic nerve paralysis or injury, and procedure time. However, PFA treatment exhibited a higher risk of cardiac perforation or tamponade.

LA PULSE: Evaluating Left Atrial Function Pre- and Post-Atrial Fibrillation Ablation Using PULSEd Field Ablation

Background: Atrial fibrillation (AF) is a common cardiac arrhythmia associated with left atrial dysfunction. The impact of pulmonary vein isolation (PVI) using pulsed field ablation (PFA) on left atrial function has not been previously quantified. This study aims to evaluate the effects of PVI using PFA on left atrial function in patients with AF. Methods: Thirty-four patients undergoing PVI with PFA between July 2022 and November 2023 were included. The left atrial function was assessed using echocardiography pre-procedure and at 6 months post-procedure. Results: The mean age of the patients was 66.5 ± 9.76 years, with 70.6% being male. The cohort included 44% of patients with paroxysmal AF. PVI was successfully achieved in all patients, with a significant improvement in all aspects of left atrial strain at an average of six-month follow-up. The left atrial strain reservoir (LASr) increased from 12.5 ± 5.8% to 21.7 ± 8.1% (p < 0.001). Notably, patients with paroxysmal AF exhibited a greater increase in LASr compared to those with persistent AF. Additionally, pre-procedural sinus rhythm was a significant predictor of better LASr outcomes. Conclusions: PFA is associated with significant improvement in left atrial reservoir strain, suggesting a positive impact on atrial function. These findings have important implications for the therapeutic management of AF and warrant further research.

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.

Comparison of Therapeutic Effects Between Pulsed Field Ablation and Cryoballoon Ablation in the Treatment of Atrial Fibrillation: A Systematic Review and Meta-analysis

Pulsed field ablation (PFA) is a novel nonthermal ablation technique for the treatment of atrial fibrillation (AF) patients, with safety comparable to traditional catheter ablation surgery. The present study aims to evaluate and compare the procedural efficiency and safety profiles of PFA and cryoballoon ablation (CBA) in the management of AF. We performed a systematic search across PubMed, the Cochrane Library, and Embase databases, encompassing the literature up to February 2024, to inform our systematic review and meta-analysis. When assessing outcome indicators, the risk ratio and its corresponding 95% confidence interval (CI) were calculated for dichotomous variables. For continuous variables, the mean difference (MD) and the associated 95% CI were determined. In this scenario, a relative risk (RR) value of less than 1 and an MD value of less than 0 are deemed favorable for the PFA group. This could translate to a reduced likelihood of procedural complications or enhanced procedural performance within the PFA group. In this analysis, 9 observational studies encompassing 2875 patients with AF were included. Among these, 38% (n = 1105) were treated with PFA, while 62% (n = 1770) received CBA. The results indicated that PFA was associated with a significantly shorter procedural duration compared with CBA, with an MD of -10.49 minutes (95% CI, -15.50 to -5.49; P < 0.0001). Nevertheless, no statistically significant differences were observed when comparing the 2 treatment cohorts concerning fluoroscopy time (MD, 0.71; 95% CI, -0.45 to 1.86; P = 0.23) and the recurrence of atrial arrhythmias during follow-up (RR, 0.95; 95% CI, 0.78-1.14; P = 0.57). In terms of perioperative complications, the PFA group showed a significantly decreased risk of phrenic nerve palsy (RR, 0.15; 95% CI, 0.06-0.39; P < 0.0001) and an increased risk of cardiac tamponade (RR, 3.48; 95% CI, 1.26-9.66; P = 0.02) compared with the CBA group. No significant differences were noted between the PFA and CBA groups regarding the incidence of stroke/transient ischemic attack (RR, 0.99; 95% CI, 0.30-3.22; P = 0.99), vascular access complication (RR, 0.87; 95% CI, 0.36-2.10; P = 0.76), atrial esophageal fistula (RR, 0.33; 95% CI, 0.01-8.13; P = 0.50), and major or minor bleeding events (RR, 0.39; 95% CI, 0.09-1.74; P = 0.22). Our research results indicate that compared with CBA, PFA not only shortens the procedure time but also demonstrates noninferiority in terms of fluoroscopy duration and the recurrence rate of atrial arrhythmias. PFA and CBA have both demonstrated their respective advantages in perioperative complications.

Safety and Efficacy of Pulse Field Ablation in the Treatment of Atrial Fibrillation and Its Comparison with Traditional Thermal Ablation: A Systematic Review and Meta-Analysis

BACKGROUND

The purpose of this meta-analysis was to evaluate the efficacy and safety of pulsed field ablation (PFA) and to compare it with the efficacy and safety of traditional thermal ablation in patients with atrial fibrillation (AF).

METHODS

PubMed, Web of Science, and Embase were searched for randomized or observational studies exploring the efficacy and safety of PFA and comparing PFA with traditional thermal ablation in patients with AF.

RESULTS

A total of 4437 patients from 16 studies that only included PFA as the ablation method and 1792 patients from 9 comparing PFA to traditional thermal ablation were included in the final analysis. In studies that considered PFA alone, the freedom from atrial arrhythmia recurrence was 0.80 (95% confidence interval [CI] 0.76-0.84), and the incidence of periprocedural complications was 0.03 (95% CI 0.02-0.05). In comparative studies, there was no significant difference in the freedom from atrial arrhythmia recurrence (odds ratio (OR) 1.24, 95% CI 0.90-1.72) and the incidence of periprocedural complications (OR 0.74, 95% CI 0.37-1.48) of PFA compared to that of traditional thermal ablation. In the subgroup with a follow-up period less than 12 months, PFA had higher freedom from atrial arrhythmia recurrence rate compared to thermal ablation (OR 2.19, 95% CI 1.14-4.20).

CONCLUSIONS

PFA is a safe and effective catheter ablation method that is not inferior to the traditional and well-established thermal ablation. It can be used as a treatment of choice for patients with AF.

THE PROSPERO REGISTRATION

CRD42023473026, https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=473026.

Left atrial posterior wall isolation in addition to pulmonary vein isolation using a pentaspline catheter in pulsed-field ablation for atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Persistent atrial fibrillation (AF) may require extensive ablation strategies. Left atrial posterior wall isolation (LAPWI) might address potential substrates for recurrence during pulsed-field ablation (PFA).

OBJECTIVE

This meta-analysis aimed to investigate the feasibility and effectiveness of LAPWI in addition to pulmonary vein isolation (PVI) using a pentaspline catheter in PFA for AF.

METHODS

Comprehensive search was conducted using PubMed, SCOPUS, ScienceDirect, and EuropePMC for studies reporting LAPWI+PVI using a pentaspline catheter in PFA ablation for AF. The primary outcome was atrial tachyarrhythmia (ATa) recurrence, defined as AF/atrial flutter/atrial tachycardia after blanking period.

RESULTS

There were 882 patients from 7 studies. The success rate of LAPWI was 100% using mean/median of 16 to 20 added PFA applications with no reported acute left atrial posterior wall reconnection and esophageal complications. In mean follow-up of 240 ± 91 days, ATa recurrence was 21% (95% CI 13%-29%; I2 = 84.8%) in the LAPWI+PVI group. Meta-regression analysis showed that age, left ventricular ejection fraction, and repeat procedure did not significantly influence ATa recurrence (P > .05). Each 1-mm increase in left atrial diameter, increases the chance of ATa recurrence by 6% (R2 = 100%, P < .001, I2 = 0%). Meta-analysis showed no difference in terms of ATa recurrence among LAPWI+PVI patients compared with those without LAPWI (odds ratio 0.78, 95% confidence interval 0.50-1.21, P = .27; I2 = 0%, P = .86). Procedure time and fluoroscopy time did not significantly differ (P > .05).

CONCLUSION

LAPWI using a pentaspline catheter during PFA was feasible and did not prolong the procedure/fluoroscopy but did not reduce ATa recurrence. LAPWI may be considered during PFA, although the benefit is uncertain.

Concurrent percutaneous left atrial appendage occlusion and catheter ablation for atrial fibrillation: State-of-the-art review

Stroke prevention and symptom control are two integral pillars in atrial fibrillation (AF) management. Percutaneous left atrial appendage occlusion (LAAO) is effective at reducing stroke risk in high-risk patients with AF who cannot tolerate oral anticoagulant therapy, whilst catheter ablation is effective at reducing AF burden and improving quality-of-life in patients who remain symptomatic despite medical therapy. If both procedures are indicated in an individual patient, they have traditionally been performed on separate occasions, due to long cumulative procedural times, itself associated with thromboembolic risk. Recently, with the advancement of procedural techniques, the concept of concurrent LAAO and AF catheter ablation has gained traction. This review summarises the evidence for and against concurrent LAAO and AF catheter ablation, discussing procedural considerations, including procedural sequencing and post-procedural antithrombotic therapy, safety and efficacy outcomes, and future directions in the field.

Efficacy and safety of pulsed-field versus conventional thermal ablation for atrial fibrillation: A systematic review and meta-analysis

Background

Pulsed-field ablation (PFA) has emerged as an innovative alternative to radiofrequency (RF) and cryoablation because it selectively targets myocardial tissue. Thus, we aim to estimate the efficacy and safety of PFA versus thermal ablation for atrial fibrillation (AF) ablation.

Methods

A systematic review and meta-analysis were retrieved from PubMed, WOS, SCOPUS, EMBASE, and CENTRAL through September 2023. We used RevMan V. 5.4 to pool dichotomous data using risk ratio (RR) and continuous data using mean difference (MD) with a 95% confidence interval (CI). PROSPERO ID: CRD42023480321.

Results

We included 17 studies with a total of 2255 patients. PFA was significantly associated with a decreased incidence of AF recurrence (RR: 0.66 with 95% CI [0.51, 0.87], p = .003). However, there was no significant difference between PFA and thermal ablation in arrhythmia recurrence (RR: 0.92 with 95% CI [0.74, 1.46], p = .42). PFA was significantly associated with decreased total procedure time (MD: -15.15 with 95% CI [-20.23, -10.07], p < .00001), decreased heart rate change (MD: -7.39 with 95% CI [-12.16, -2.62], p = .002), decreased phrenic nerve palsy (RR: 0.38 with 95% CI [0.15, 0.98], p = .05), and reduced esophageal lesions (RR: 0.09 with 95% CI [0.01, 0.69], p = .02). On the contrary, PFA was significantly associated with increased pericardial tamponade (RR: 6.14 with 95% CI [1.43, 26.33], p = .01).

Conclusion

PFA was significantly associated with decreased AF recurrence, total procedure time, heart rate change, phrenic nerve palsy, esophageal lesion, and increased incidence of pericardial tamponade compared with thermal ablation.

Management of Left Atrial Tachyrhythms in the Setting of HFpEF with Pulsed-Field Ablation: Treating Fire with Water?

Atrial fibrillation (AF) in the setting of heart failure (HF) with preserved ejection fraction (HFpEF) is a prevalent comorbidity and is enabled by adverse left atrial (LA) remodeling, dilation, and scar tissue formation. These changes are facilitated by poor left ventricular compliance. A growing body of clinical evidence and medical guidelines suggest that managing atrial tachyrhythms with catheter ablation (CA) is paramount to treating concomitant HF. This recommendation is complicated in that thermal CA modalities, namely radiofrequency ablation and cryoablation, are both therapeutic via inducing additional scar tissue. AF treatment with thermal CA may compound the atrial scar burden for patients who already have extensive scars secondary to HFpEF. Therefore, thermal CA could act as "gasoline" to the slowly burning "fire" within the LA, increasing the rate of AF recurrence. Pulsed-field ablation (PFA), which utilizes high-voltage irreversible electroporation, is a non-thermal CA technique that is capable of disrupting reentrant microcircuits and arrhythmogenic foci without inducing significant scar burden. PFA has the potential to mitigate the strong fibrosis response to thermal CA that predisposes to AF by serving as "water" rather than "gasoline". Thus, PFA may increase the efficacy and durability of CA for AF in HFpEF, and subsequently, may decrease the risk of procedural complications from repeat CAs. In this article, we provide a summary of the clinical concepts underlying HFpEF and AF and then summarize the data to date on the potential of PFA being a superior CA technique for AF in the setting of comorbid HFpEF.

Meta-analysis of Pulsed Field Ablation Versus Thermal Ablation for Pulmonary Vein Isolation in AF: A Broad Overview Focusing on Efficacy, Safety and Outcomes

The recently established non-thermal, single-shot pulsed field ablation (PFA) is a potential tool for achieving rapid pulmonary vein isolation (PVI) to cause cell death by electroporation, yet data regarding this state-of-the-art technology remain sparse. In this meta-analysis, we included 3,857 patients from 20 studies. There was no significant difference in AF recurrence between the PFA and control groups. Subgroup analysis showed that additional ablation beyond PVI has a similar rate of AF recurrence to PVI alone (10% versus 13%, respectively). PVI durability was achieved in 83% (mean), 95% CI [65-99%] of the PFA group and in 79% (mean), 95% CI [60-98%] of the control group, with no significant difference in the rate of PVI durability between the two groups. The PFA group had considerably reduced procedure duration, but not fluoroscopy time. No statistically significant differences in periprocedural complications were observed. PFA is associated with shorter procedural time than thermal ablation. Cardiac complications were uncommon and mainly reversible in both the PFA and control groups.

Safety and effectiveness of additional left atrial posterior wall ablation using pulsed field ablation for persistent and long-standing persistent atrial fibrillation patients

INTRODUCTION

The unique safety profile of pulsed field ablation (PFA) has made pulmonary vein isolation (PVI) + left atrial posterior wall (LAPW) ablation promising for treating persistent atrial fibrillation (PerAF). The goal of this study was to assess long-term freedom from atrial fibrillation, atrial flutter, and atrial tachycardia (AF/AFL/AT), as well as the safety and feasibility of LAPW PFA using multipolar, pentaspline Farawave catheter.

METHODS

Retrospective observational study at a single institution. Data for 94 patients were collected from a prespecified intraprocedural registry. The long-term AF/AFL/AT recurrence assessment was based on an analysis of medical history; 24-h Holter ECGs at 3, 6, and 12 months postablation; and 12-lead ECGs recorded during symptomatic episodes or visits.

RESULTS

Half of the patients had ls-PerAF, and half had a history of catheter ablation-mostly RF PVI. The acute ablation success rate was 100%, and the primary safety outcome was observed in 2 patients. Fifty patients experienced AF/AFL/AT recurrence (54.3%). An increase in LAPW low-voltage areas and AF classification were associated with arrhythmia recurrence. After a median follow-up of 13 months, the Kaplan‒Meier estimated median time free of AF/AFL/AT after a single procedure was 14.7 months.

CONCLUSION

PFA PVI + PWA had the best outcome in perAF patients without extensive LA fibrosis. AF recurrence was paroxysmal in significant part of the cohort. The addition of PWA to PVI using multipolar PFA was safe and did not significantly influence the transpired ablation time.

Feasibility study on atrial fibrillation ablation with pulsed field ablation and concomitant occlusion of the left atrial appendage

AIMS

Atrial fibrillation (AF) ablation and left atrial appendage occlusion (LAAO) are increasingly performed as individual procedures. Pulsed field ablation (PFA) has significantly reduced procedure duration and may be advantageous for the combined approach.

METHODS AND RESULTS

We have launched a programme for simultaneous AF ablation using PFA and LAAO for patients qualifying for both treatments and excluding those with a complex anatomy. We compare procedure duration and fluoroscopy time against individual procedures (either AF ablation or LAAO alone), all performed by the same operators and using consistent technologies. We performed the combined procedure in 10 patients (50% males; median age 70 years) and excluded 2 patients (17%) because of a complex left atrial appendage anatomy. No death, stroke, or major bleeding events, including pericardial effusion, occurred. For single-procedure comparison, 207 AF ablation procedures and 61 LAAO procedures were available. The total median procedure duration was 79 min (range 60-125) for the combined procedure, 71 min (25-241) for individual AF ablation (51 min without and 78 min with 3-dimensional electroanatomic mapping), and 47 min (15-162) for individual LAAO. The respective fluoroscopy times were 21 (15-26), 15 (5-44), and 10 (3-50) min. For the combined procedure, femoral vein access to last PFA application lasted 49 min (34-93) and LAAO added 20 min (15-37).

CONCLUSION

Simultaneous PFA-based AF ablation and LAAO in carefully selected patients is feasible and safe and can be executed within a short overall procedure duration.

Global research progress on radiofrequency ablation in cardiology: A bibliometric analysis (2004-2023)

In recent years, significant advancements in radiofrequency ablation technology have notably enhanced arrhythmia treatment in cardiology. Technological advancements and increasing clinical adoption have made radiofrequency ablation a key therapy in improving life quality for patients with conditions like atrial fibrillation (AF). Consequently, there has been a marked increase in research output, underscoring the technology's significance and its potential in cardiology. Aims to comprehensively analyze cardiology's radiofrequency ablation research trends, identifying leading countries and institutions in international collaborations, key researchers' contributions, and evolving research hotspots. The study, based on the Web of Science Core Collection database, reviewed the literatures from 2004 to 2023. CiteSpace 6.2.R7 Basic was used for bibliometric analysis, which examined annual publication trends, international collaboration networks, key authors, leading research institutions, major journals, keyword co-occurrence and clustering trends. Analyzing 3423 relevant articles, this study reveals a consistent growth in cardiology radiofrequency ablation research since 2004. The analysis shows that the United States, Germany, and France hold central roles in the international collaboration network, with leading authors from premier US and European institutions. Keyword cluster analysis identifies "atrial flutter" and "ventricular tachycardia" as current research focal points. Cardiology radiofrequency ablation research shows a growth trend, led by the United States and European countries. Research hotspots are concentrated on the diverse applications of radiofrequency ablation technology and the treatment of AF. Future studies may increasingly focus on technological innovation and the deepening of clinical applications.

Pulsed electric field performance calculator tool based on an in vitro human cardiac model

Introduction

Pulsed Field Ablation (PFA) is a novel non-thermal method for cardiac ablation, relying on irreversible electroporation induced by high-energy pulsed electric fields (PEFs) to create localized lesions in the heart atria. A significant challenge in optimizing PFA treatments is determining the lethal electric field threshold (EFT), which governs ablation volume and varies with PEF waveform parameters. However, the proprietary nature of device developer's waveform characteristics and the lack of standardized nonclinical testing methods have left optimal EFTs for cardiac ablation uncertain.

Methods

To address this gap, we introduced a laboratory protocol employing human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in monolayer format to evaluate the impact of a range of clinically relevant biphasic pulse parameters on lethal EFT and adiabatic heating (AH). Cell death areas were assessed using fluorescent dyes and confocal microscopy, while lethal EFTs were quantified through comparison with electric field numerical simulations.

Results and conclusion

Our study confirmed a strong correlation between cell death in hiPSC-CMs and the number and duration of pulses in each train, with pulse repetition frequency exerting a comparatively weaker influence. Fitting of these results through machine learning algorithms were used to develop an open-source online calculator. By estimating lethal EFT and associated temperature increases for diverse pulse parameter combinations, this tool, once validated, has the potential to significantly reduce reliance on animal models during early-stage device de-risking and performance assessment. This tool also offers a promising avenue for advancing PFA technology for cardiac ablation medical devices to enhance patient outcomes.

Pulsed-field ablation versus thermal ablation for atrial fibrillation: A meta-analysis

Background

Pulsed-field ablation (PFA) is an alternative to thermal ablation (TA) in patients with atrial fibrillation (AF) receiving catheter-based therapy for pulmonary vein isolation (PVI). However, its efficacy and safety have yet to be fully elucidated.

Objective

The purpose of this study was to compare the acute and long-term efficacies and safety of PFA and TA.

Methods

We performed a systematic review and meta-analysis of randomized and nonrandomized controlled trials comparing PFA and TA in patients with AF undergoing their first PVI ablation. The TA group was divided into cryoballoon (CB) and radiofrequency subgroups. AF patients were divided into paroxysmal atrial fibrillation (PAF) and persistent atrial fibrillation (PersAF) subgroups for further analysis.

Results

Eighteen studies involving 4998 patients (35.2% PFA) were included. Overall, PFA was associated with a shorter procedure time (mean difference [MD] -21.68; 95% confidence interval [CI] -32.81 to -10.54) but longer fluoroscopy time (MD 4.53; 95% CI 2.18-6.88) than TA. Regarding safety, lower (peri-)esophageal injury rates (odds ratio [OR] 0.17; 95% CI 0.06-0.46) and higher tamponade rates (OR 2.98; 95% CI 1.27-7.00) were observed after PFA. In efficacy assessment, PFA was associated with a better first-pass isolation rate (OR 6.82; 95% CI 1.37-34.01) and a lower treatment failure rate (OR 0.83; 95% CI 0.70-0.98). Subgroup analysis showed no differences in PersAF and PAF. CB was related to higher (peri)esophageal injury, and lower PVI acute success and procedural time.

Conclusion

Compared to TA, PFA showed better results with regard to acute and long-term efficacy but significant differences in safety, with lower (peri)esophageal injury rates but higher tamponade rates in procedural data.

Pulsed Field Energy in Atrial Fibrillation Ablation: From Physical Principles to Clinical Applications

Atrial fibrillation, representing the most prevalent sustained cardiac arrhythmia, significantly impacts stroke risk and cardiovascular mortality. Historically managed with antiarrhythmic drugs with limited efficacy, and more recently, catheter ablation, the interventional approach field is still evolving with technological advances. This review highlights pulsed field ablation (PFA), a revolutionary technique gaining prominence in interventional electrophysiology because of its efficacy and safety. PFA employs non-thermal electric fields to create irreversible electroporation, disrupting cell membranes selectively within myocardial tissue, thus preventing the non-selective damage associated with traditional thermal ablation methods like radiofrequency or cryoablation. Clinical studies have consistently shown PFA's ability to achieve pulmonary vein isolation-a cornerstone of AF treatment-rapidly and with minimal complications. Notably, PFA reduces procedure times and has shown a lower incidence of esophageal and phrenic nerve damage, two common concerns with thermal techniques. Emerging from oncological applications, the principles of electroporation provide a unique tissue-selective ablation method that minimizes collateral damage. This review synthesizes findings from foundational animal studies through to recent clinical trials, such as the MANIFEST-PF and ADVENT trials, demonstrating PFA's effectiveness and safety. Future perspectives point towards expanding indications and refinement of techniques that promise to improve AF management outcomes further. PFA represents a paradigm shift in AF ablation, offering a safer, faster, and equally effective alternative to conventional methods. This synthesis of its development and clinical application outlines its potential to become the new standard in AF treatment protocols.

Pre- and post-procedural cardiac imaging (computed tomography and magnetic resonance imaging) in electrophysiology: a clinical consensus statement of the European Heart Rhythm Association and European Association of Cardiovascular Imaging of the European Society of Cardiology

Imaging using cardiac computed tomography (CT) or magnetic resonance (MR) imaging has become an important option for anatomic and substrate delineation in complex atrial fibrillation (AF) and ventricular tachycardia (VT) ablation procedures. Computed tomography more common than MR has been used to detect procedure-associated complications such as oesophageal, cerebral, and vascular injury. This clinical consensus statement summarizes the current knowledge of CT and MR to facilitate electrophysiological procedures, the current value of real-time integration of imaging-derived anatomy, and substrate information during the procedure and the current role of CT and MR in diagnosing relevant procedure-related complications. Practical advice on potential advantages of one imaging modality over the other is discussed for patients with implanted cardiac rhythm devices as well as for planning, intraprocedural integration, and post-interventional management in AF and VT ablation patients. Establishing a team of electrophysiologists and cardiac imaging specialists working on specific details of imaging for complex ablation procedures is key. Cardiac magnetic resonance (CMR) can safely be performed in most patients with implanted active cardiac devices. Standard procedures for pre- and post-scanning management of the device and potential CMR-associated device malfunctions need to be in place. In VT patients, imaging-specifically MR-may help to determine scar location and mural distribution in patients with ischaemic and non-ischaemic cardiomyopathy beyond evaluating the underlying structural heart disease. Future directions in imaging may include the ability to register multiple imaging modalities and novel high-resolution modalities, but also refinements of imaging-guided ablation strategies are expected.

Pulsed field ablation versus thermal energy ablation for atrial fibrillation: a systematic review and meta-analysis of procedural efficiency, safety, and efficacy

BACKGROUND

Pulsed field ablation (PFA) induces cell death through electroporation using ultrarapid electrical pulses. We sought to compare the procedural efficiency characteristics, safety, and efficacy of ablation of atrial fibrillation (AF) using PFA compared with thermal energy ablation.

METHODS

We performed an extensive literature search and systematic review of studies that compared ablation of AF with PFA versus thermal energy sources. Risk ratio (RR) 95% confidence intervals (CI) were measured for dichotomous variables and mean difference (MD) 95% CI were measured for continuous variables, where RR < 1 and MD < 0 favor the PFA group.

RESULTS

We included 6 comparative studies for a total of 1012 patients who underwent ablation of AF: 43.6% with PFA (n = 441) and 56.4% (n = 571) with thermal energy sources. There were significantly shorter procedures times with PFA despite a protocolized 20-min dwell time (MD - 21.95, 95% CI - 33.77, - 10.14, p = 0.0003), but with significantly longer fluroscopy time (MD 5.71, 95% CI 1.13, 10.30, p = 0.01). There were no statistically significant differences in periprocedural complications (RR 1.20, 95% CI 0.59-2.44) or recurrence of atrial tachyarrhythmias (RR 0.64, 95% CI 0.31, 1.34) between the PFA and thermal ablation cohorts.

CONCLUSIONS

Based on the results of this meta-analysis, PFA was associated with shorter procedural times and longer fluoroscopy times, but no difference in periprocedural complications or rates of recurrent AF when compared to ablation with thermal energy sources. However, larger randomized control trials are needed.

Pulmonary vein isolation plus adjunctive therapy for the treatment of atrial fibrillation: a systematic review and meta-analysis

BACKGROUND

Pulmonary vein isolation (PVI) is the primary technique for ablation of atrial fibrillation (AF). It is unclear whether adjunctive therapies in addition to PVI can reduce atrial arrhythmia recurrence (AAR) compared to PVI alone in patients with AF.

METHODS

A meta-analysis of randomized controlled trials comparing PVI plus an adjunctive therapy (autonomic modulation, linear ablation, non-pulmonary vein trigger ablation, epicardial PVI [hybrid ablation], or left atrial substrate modification) to PVI alone was conducted. The primary outcome was AAR. Cumulative odd's ratios (OR) and 95% confidence intervals (CI) were calculated for each treatment type.

RESULTS

Forty-six trials were identified that included 8,500 participants. The mean age (± standard deviation) was 60.2 (±4.1) years, and 27.2% of all patients were female. The mean follow-up time was 14.6 months. PVI plus autonomic modulation and PVI plus hybrid ablation were associated with a relative 53.1% (OR 0.47; 95% CI 0.32 to 0.69; p < 0.001) and 59.1% (OR 0.41; 95% CI 0.23 to 0.75; p = 0.003) reduction in AAR, respectively, compared to PVI alone. All categories had at least moderate interstudy heterogeneity except for hybrid ablation.

CONCLUSION

Adjunctive autonomic modulation and epicardial PVI may improve the effectiveness of PVI. Larger, multi-center randomized controlled trials are needed to evaluate the efficacy of these therapies.

Potential consequences of cardioneuroablation for vasovagal syncope: A call for appropriately designed, sham-controlled clinical trials

Cardioneuroablation (CNA) is being increasingly used to treat patients with vasovagal syncope (VVS). Bradycardia, in the cardioinhibitory subtype of VVS, results from transient parasympathetic overactivity leading to sinus bradycardia and/or atrioventricular block. By mitigating parasympathetic overactivity, CNA has been shown to improve VVS symptoms in clinical studies with relatively small sample sizes and short follow-up periods (<5 years) at selected centers. However, CNA may potentially tip the autonomic balance to a state of sympathovagal imbalance with attenuation of cardiac parasympathetic activity. A higher heart rate is associated with adverse cardiovascular events and increased mortality in healthy populations without cardiovascular diseases. Chronic sympathovagal imbalance may also affect the pathophysiology of spectra of cardiovascular disorders including atrial and ventricular arrhythmias. This review addresses potential long-term pathophysiological consequences of CNA for VVS.

Acute Kidney Injury Resulting From Hemoglobinuria After Pulsed-Field Ablation in Atrial Fibrillation: Is it Preventable?

BACKGROUND

High-voltage pulses can cause hemolysis.

OBJECTIVES

The authors evaluated the occurrence of hemoglobinuria after pulsed-field ablation (PFA) and its impact on renal function in patients with atrial fibrillation (AF).

METHODS

A consecutive series of patients with AF undergoing PFA were included in this analysis. The initial patients who did not receive postablation hydration immediately after the procedure were classified as group 1 (n = 28), and the rest of the study patients who received planned fluid infusion (0.9% sodium chloride ≥2 L) after the procedure were categorized as group 2 (n = 75).

RESULTS

Of the 28 patients in group 1, 21 (75%) experienced hemoglobinuria during the 24 hours after catheter ablation. The mean postablation serum creatinine (S-Cr) was significantly higher than the baseline value in those 21 patients (1.46 ± 0.28 mg/dL vs 0.86 ± 0.24 mg/dL, P < 0.001). Of those 21 patients, 4 (19%) had S-Cr. >2.5 mg/dL (mean: 2.95 ± 0.21 mg/dL). The mean number of PF applications was significantly higher in those 4 patients than in the other 17 patients experiencing hemoglobinuria (94.63 ± 3.20 vs 46.75 ± 9.10, P < 0.001). In group 2 patients, no significant changes in S-Cr were noted. The group 2 patients received significantly higher amounts of fluid infusion after catheter ablation than did those in group 1 (2,082.50 ± 258.08 mL vs 494.01 ± 71.65 mL, P < 0.001). In multivariable analysis, both hydration (R2 = 0.63, P < 0.01) and number of PFA applications (R2 = 0.33, P < 0.01) were independent predictors of postprocedure acute kidney injury.

CONCLUSIONS

On the basis of our findings, both the number of PFA applications and postablation hydration were independent predictors of renal insult that could be prevented using planned fluid infusion immediately after the procedure.

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

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

Pulmonary vein narrowing after pulsed field versus thermal ablation

AIMS

When it occurs, pulmonary vein (PV) stenosis after atrial fibrillation (AF) ablation is associated with significant morbidity. Even mild-to-moderate PV narrowing may have long-term implications. Unlike thermal ablation energies, such as radiofrequency (RF) or cryothermy, pulsed field ablation (PFA) is a non-thermal modality associated with less fibrotic proliferation. Herein, we compared the effects of PFA vs. thermal ablation on PV narrowing after AF ablation.

METHODS AND RESULTS

ADVENT was a multi-centre, randomized, single-blind study comparing PFA (pentaspline catheter) with thermal ablation-force-sensing RF or cryoballoon (CB)-to treat drug-refractory paroxysmal AF. Pulmonary vein diameter and aggregate cross-sectional area were obtained by baseline and 3-month imaging. The pre-specified, formally tested, secondary safety endpoint compared a measure of PV narrowing between PFA vs. thermal groups, with superiority defined by posterior probability > 0.975. Among subjects randomized to PFA (n = 305) or thermal ablation (n = 302), 259 PFA and 255 thermal ablation (137 RF and 118 CB) subjects had complete baseline and 3-month PV imaging. No subject had significant (≥70%) PV stenosis. Change in aggregate PV cross-sectional area was less with PFA (-0.9%) than thermal ablation (-12%, posterior probability > 0.999)-primarily driven by the RF sub-cohort (-19.5%) vs. CB sub-cohort (-3.3%). Almost half of all PFA PV diameters did not decrease, but the majority (80%) of RF PVs decreased, regardless of PV anatomic location.

CONCLUSION

In this first randomized comparison of PFA vs. thermal ablation, PFA resulted in less PV narrowing-thereby underscoring the qualitatively differential and favourable impact of PFA on PV tissue.

Myocardial injury and inflammation following pulsed-field ablation and very high-power short-duration ablation for atrial fibrillation

INTRODUCTION

Pulmonary vein isolation (PVI) using radiofrequency ablation (RFA) is an established treatment strategy for atrial fibrillation (AF). To improve PVI efficacy and safety, high-power short-duration (HPSD) ablation and pulsed-field ablation (PFA) were recently introduced into clinical practice. This study aimed to determine the extent of myocardial injury and systemic inflammation following PFA, HPSD, and standard RFA using established biomarkers.

METHODS

We included 179 patients with paroxysmal AF receiving first-time PVI with different ablation technologies: standard RFA (30-40 W/20-30 s, n = 52), power-controlled HPSD (70 W/5-7 s, n = 60), temperature-controlled HPSD (90 W/4 s, n = 32), and PFA (biphasic, bipolar waveform, n = 35). High-sensitivity cardiac troponin T (hs-cTnT), creatine kinase (CK), CK MB isoform (CK-MB), and white blood cell (WBC) count were determined before and after ablation.

RESULTS

Baseline characteristics were well-balanced between groups (age 63.1 ± 10.3 years, 61.5% male). Postablation hs-cTnT release was significantly higher with PFA (1469.3 ± 495.0 ng/L), HPSD-70W (1322.3 ± 510.6 ng/L), and HPSD-90W (1441.2 ± 409.9 ng/L) than with standard RFA (1045.9 ± 369.7 ng/L; p < .001). CK and CK-MB release was increased with PFA by 3.4-fold and 5.8-fold, respectively, as compared to standard RFA (p < .001). PFA was associated with the lowest elevation in WBC (Δ1.5 ± 1.5 × 109 /L), as compared to standard RFA (Δ3.8 ± 2.5 × 109 /L, p < .001), HPSD-70W (Δ2.7 ± 1.7 × 109 /L, p = .037), and HPSD-90W (Δ3.6 ± 2.5 × 109 /L, p < .001).

CONCLUSION

Among the four investigated ablation technologies, PFA was associated with the highest myocardial injury and the lowest inflammatory reaction.

Pulsed field ablation of spatiotemporal electrogram dispersion following pulmonary vein isolation and left atrial linear lesions for persistent atrial fibrillation: a case report

Background

Ablation of persistent atrial fibrillation (AF) remains challenging, with atrial substrate modification often being performed as an adjunct to pulmonary vein isolation (PVI). Pulsed field ablation (PFA) is a novel ablation modality that carries a favourable safety profile, which could facilitate complex procedures.

Case summary

We present the case of a 60-year-old male undergoing catheter ablation for symptomatic persistent AF. The procedure was performed with the Farapulse™ PFA system in a stepwise manner, including PVI and linear lesions for the isolation of the posterior left atrial wall and the ablation of the mitral isthmus. The final step of the procedure included the ablation of areas exhibiting spatiotemporal electrogram dispersion, identified with the help of artificial intelligence-based software (VX1, Volta Medical) in both atria. Sinus rhythm was restored after the abolition of an electrogram dispersion zone in the right atrium. The procedure was carried out without any complications.

Discussion

Complex ablation procedures for persistent AF can be successfully performed with PFA. In the context of such extensive ablation strategies, PFA is an attractive energy source, given its non-thermal nature that is known to prevent damage to surrounding tissue and result in less chronic fibrosis. However, caution should be exercised to avoid excessive ablation when using the currently available multispline PFA catheter, as it may inadvertently target adjacent areas of healthy myocardium.

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.

Atrial Ablation Lesion Evaluation by Cardiac Magnetic Resonance: Review of Imaging Strategies and Histological Correlations

Cardiac magnetic resonance (CMR) imaging is a valuable noninvasive tool for evaluating tissue response following catheter ablation of atrial tissue. This review provides an overview of the contemporary CMR strategies to visualize atrial ablation lesions in both the acute and chronic postablation stages, focusing on their strengths and limitations. Moreover, the accuracy of CMR imaging in comparison to atrial lesion histology is discussed. T2-weighted CMR imaging is sensitive to edema and tends to overestimate lesion size in the acute stage after ablation. Noncontrast agent-enhanced T1-weighted CMR imaging has the potential to provide more accurate assessment of lesions in the acute stage but may not be as effective in the chronic stage. Late gadolinium enhancement imaging can be used to detect chronic atrial scarring, which may inform repeat ablation strategies. Moreover, novel imaging strategies are being developed, but their efficacy in characterizing atrial lesions is yet to be determined. Overall, CMR imaging has the potential to provide virtual histology that aids in evaluating the efficacy and safety of catheter ablation and monitoring of postprocedural myocardial changes. However, technical factors, scanning during arrhythmia, and transmurality assessment pose challenges. Therefore, further research is needed to develop CMR strategies to visualize the ablation lesion maturation process more effectively.

Pulsed Field or Conventional Thermal Ablation for Paroxysmal Atrial Fibrillation

BACKGROUND

Catheter-based pulmonary vein isolation is an effective treatment for paroxysmal atrial fibrillation. Pulsed field ablation, which delivers microsecond high-voltage electrical fields, may limit damage to tissues outside the myocardium. The efficacy and safety of pulsed field ablation as compared with conventional thermal ablation are not known.

METHODS

In this randomized, single-blind, noninferiority trial, we assigned patients with drug-refractory paroxysmal atrial fibrillation in a 1:1 ratio to undergo pulsed field ablation or conventional radiofrequency or cryoballoon ablation. The primary efficacy end point was freedom from a composite of initial procedural failure, documented atrial tachyarrhythmia after a 3-month blanking period, antiarrhythmic drug use, cardioversion, or repeat ablation. The primary safety end point included acute and chronic device- and procedure-related serious adverse events.

RESULTS

A total of 305 patients were assigned to undergo pulsed field ablation, and 302 were assigned to undergo thermal ablation. At 1 year, the primary efficacy end point was met (i.e., no events occurred) in 204 patients (estimated probability, 73.3%) who underwent pulsed field ablation and 194 patients (estimated probability, 71.3%) who underwent thermal ablation (between-group difference, 2.0 percentage points; 95% Bayesian credible interval, -5.2 to 9.2; posterior probability of noninferiority, >0.999). Primary safety end-point events occurred in 6 patients (estimated incidence, 2.1%) who underwent pulsed field ablation and 4 patients (estimated incidence, 1.5%) who underwent thermal ablation (between-group difference, 0.6 percentage points; 95% Bayesian credible interval, -1.5 to 2.8; posterior probability of noninferiority, >0.999).

CONCLUSIONS

Among patients with paroxysmal atrial fibrillation receiving a catheter-based therapy, pulsed field ablation was noninferior to conventional thermal ablation with respect to freedom from a composite of initial procedural failure, documented atrial tachyarrhythmia after a 3-month blanking period, antiarrhythmic drug use, cardioversion, or repeat ablation and with respect to device- and procedure-related serious adverse events at 1 year. (Funded by Farapulse-Boston Scientific; ADVENT ClinicalTrials.gov number, NCT04612244.).

Visualization of fibroblast activation using 68Ga-FAPI PET/CT after pulmonary vein isolation with pulsed field compared with cryoballoon ablation

BACKGROUND

Pulsed-field ablation (PFA) is a novel ablation modality for atrial fibrillation (AF) ablating myocardium by electroporation without tissue-heating. With its different mechanism of tissue ablation, it is assumed that lesion creation is divergent to thermal energy sources. 68Ga-fibroblast-activation protein inhibitor (FAPI) PET/CT targets FAP-alpha expressed by activated fibroblasts. We aimed to assess 68Ga-FAPI uptake in pulmonary veins as surrogate for ablation damage after PFA and cryoballoon ablation (CBA).

METHODS

26 patients (15 PFA, 11 CBA) underwent 68Ga-FAPI-PET/CT after ablation. Standardized uptake values (SUV) and fibroblast-activation volumes of localized tracer uptake were assessed.

RESULTS

Patient characteristics were comparable between groups. In PFA, focal FAPI uptake was only observed in 3/15 (20%) patients, whereas in the CBA cohort, 10/11 (90.9%) patients showed atrial visual uptake. We observed lower values of SUVmax (2.85 ± 0.56 vs 4.71 ± 2.06, P = 0.025) and FAV (1.13 ± 0.84 cm3 vs 3.91 ± 2.74 cm3, P = 0.014) along with a trend towards lower SUVpeak and SUVmean in PFA vs CBA patients, respectively.

CONCLUSION

Tissue response with respect to fibroblast activation seems to be less pronounced in PFA compared to established thermal ablation systems. This functional assessment might contribute to a better understanding of lesion formation in thermal and PFA ablation potentially contributing to better safety outcomes.

Safety and acute efficacy of catheter ablation for atrial fibrillation with pulsed field ablation vs thermal energy ablation: A meta-analysis of single proportions

Background

Pulsed field ablation (PFA) has emerged as a novel energy source for the ablation of atrial fibrillation (AF) using ultrarapid electrical pulses to induce cell death via electroporation.

Objective

The purpose of this study was to compare the safety and acute efficacy of ablation for AF with PFA vs thermal energy sources.

Methods

We performed an extensive literature search and systematic review of studies that evaluated the safety and efficacy of ablation for AF with PFA and compared them to landmark clinical trials for ablation of AF with thermal energy sources. Freeman-Tukey double arcsine transformation was used to establish variance of raw proportions followed by the inverse with the random-effects model to combine the transformed proportions and generate the pooled prevalence and 95% confidence interval (CI).

Results

We included 24 studies for a total of 5203 patients who underwent AF ablation. Among these patients, 54.6% (n = 2842) underwent PFA and 45.4% (n = 2361) underwent thermal ablation. There were significantly fewer periprocedural complications in the PFA group (2.05%; 95% CI 0.94-3.46) compared to the thermal ablation group (7.75%; 95% CI 5.40-10.47) (P = .001). When comparing AF recurrence up to 1 year, there was a statistically insignificant trend toward a lower prevalence of recurrence in the PFA group (14.24%; 95% CI 6.97-23.35) compared to the thermal ablation group (25.98%; 95% CI 15.75-37.68) (P = .132).

Conclusion

Based on the results of this meta-analysis, PFA was associated with lower rates of periprocedural complications and similar rates of acute procedural success and recurrent AF with up to 1 year of follow-up compared to ablation with thermal energy sources.

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

BACKGROUND

We describe our initial experience using a multipolar pulsed-field ablation catheter for the treatment of left atrial (LA) reentry tachycardia.

METHODS

We included all patients with LA reentry tachycardia treated with PFA at our institution between September 2021 and March 2022. The tachycardia mechanism was identified using 3D electro-anatomical mapping (3D-EAM). Subsequently, a roof line, anterior line, or mitral isthmus line was ablated as appropriate. Roof line ablation was always combined with LA posterior wall (LAPW) ablation. Positioning of the PFA catheter was guided by a 3D-EAM system and by fluoroscopy. Bidirectional block across lines was verified using standard criteria. Additional radiofrequency ablation (RFA) was used to achieve bidirectional block as necessary.

RESULTS

Among 22 patients (median age 70 (59-75) years; 9 females), we identified 27 LA reentry tachycardia: seven roof dependent macro-reentries, one posterior-wall micro-reentry, twelve peri-mitral macro-reentries, and seven anterior-wall micro-reentries. We ablated a total of 20 roof lines, 13 anterior lines, and 6 mitral isthmus lines. Additional RFA was necessary for two anterior lines (15%) and three mitral isthmus lines (50%). Bidirectional block was achieved across all roof lines, 92% of anterior lines, and 83% of mitral isthmus lines. We observed no acute procedural complications.

CONCLUSION

Ablation of a roof line and of the LAPW is feasible, effective, and safe using this multipolar PFA catheter. However, the catheter is less suited for ablation of the mitral isthmus and the anterior line. A focal pulsed-field ablation catheter may be more effective for ablation of these lines. This study shows the feasibility to ablate linear lesions with a multipolar pulsed-field ablation catheter. 27 left atrial reentry tachycardia were treated in 22 patients.

Case Series of Ventricular Tachycardia Ablation With Pulsed-Field Ablation: Pushing Technology Further (Into the Ventricle)

Three cases of ventricular tachycardia ablation with pulsed-field ablation technology performed at 2 separate centers are reported, highlighting the advantages and disadvantages of this tool inside the ventricle: its dependence on proximity rather than contact makes it useful in sites with poor stability, while the speed of application and large scope of action provided by commercially available catheters could help with ablating large diseased areas of endocardium in a fast and hemodynamically well-tolerated fashion. However, lesion depth could be insufficient for guaranteeing efficacy in preventing ventricular tachycardias originating at an epicardial site, even in the right ventricle.