Acute safety, efficacy, and advantages of a novel cryoballoon ablation system for pulmonary vein isolation in patients with paroxysmal atrial fibrillation: initial clinical experience

Best practices IV in cryoballoon ablation of atrial fibrillation: Important clinical and practical differences for new compliant and size-adjustable cryoballoon systems

BACKGROUND

This paper aims to review and compare the mechanical and technical similarities and differences between the Arctic Front series cryoballoons from Medtronic and the next-generation cryoballoons, including POLARx and POLARx FIT from Boston Scientific and Nordica from Synaptic. As cryoballoon technology continues to evolve, the introduction of lower-pressure and selectable-size balloons presents new considerations for both safety and efficacy of cryoablation of atrial fibrillation.

Novel vs established cryoballoon ablation system for atrial fibrillation: A systematic review and meta-analysis

Background

Recently, a novel cryoballoon ablation system (POLARx) for the treatment of atrial fibrillation has been introduced.

Objective

We aimed at systematically reviewing the efficacy and safety of the POLARx compared with the ArcticFront system.

Methods

Structured systematic database search for articles published between 2021 and 2024 reporting the efficacy and/or safety of the POLARx system for atrial fibrillation ablation. The co-primary endpoints were the long-term efficacy and safety of the POLARx system.

Results

Of the 24 studies with 5364 patients (weighted mean age 62.4 years) included, 15 compared the POLARx system (1746 patients) with the ArcticFront system (2282 patients). Despite significantly lower temperatures at isolation (POLARx -46.3 °C, ArcticFront -31.6 °C, P < .01) and nadir temperatures (POLARx -56.5 °C, ArcticFront -47.8 °C, P < .01), the POLARx system did not show a better acute (98.9% and 99.2% successfully ablated patients and 99.5% and 99.8% successfully ablated pulmonary veins in the POLARx and ArcticFront groups, respectively) or long-term (after a weighted mean follow-up of 12.6 months, the success rate was 69.5% with POLARx and 60.2% with ArcticFront, P = .98) efficacy. While most complications were similar between the POLARx and ArcticFront groups, the incidence of phrenic nerve palsies in the pooled cohorts (all POLARx vs all ArcticFront control patients) differed (2.7% vs 1.6% in the POLARx vs ArcticFront groups; odds ratio 1.79, 95% confidence interval 1.14-2.83, P = .01).

Conclusion

The novel POLARx system provided similar efficiency and acute/long-term efficacy but showed a higher incidence of phrenic nerve palsies compared with the ArcticFront system.

Using computed tomography atrial myocardial thickness maps in cryoballoon pulmonary vein isolation: the UTMOST AF II randomized clinical trial

AIMS

Whether adjusting the duration of ablation based on left atrial wall thickness (LAWT) provides extra benefits for pulmonary vein (PV) isolation for atrial fibrillation (AF) is uncertain. We studied the safety and efficacy of tailored cryoballoon PV isolation (CB-PVI) based on LAWT for paroxysmal AF.

METHODS AND RESULTS

Two hundred seventy-seven patients with paroxysmal AF refractory to anti-arrhythmic drug were randomized 1:1 to either LAWT-guided CB-PVI (n = 135) and empirical CB-PVI (n = 142). Empirical CB-PVI was performed using a 28 mm cryoballoon with recommended application for 240 s per ablation. Cryoapplication in the LAWT-guided group was titrated (additional application for 120 s at PVs, where >25% of the circumference includes segments with LAWT > 2.5 mm and reduced baseline application to 180 s at PVs where >75% of the circumference includes segments with LAWT < 1.5 mm) according to the computed tomography LAWT colour map. The primary endpoint was freedom from any documented atrial arrhythmia of more than 30 s without antiarrhythmic medication, after a single ablation procedure. During a mean follow-up of 18.7 months, patients in the LAWT-guided CB-PVI group (70.8%) had a higher event-free rate from primary endpoint than those in the empirical CB-PVI group (54.4%; hazard ratio 0.64, 95% confidence interval 0.42-0.99; P = 0.043). No differences were observed between the groups in complication rates (3.0% in LAWT-guided vs. 4.9% in empirical CB-PVI). The total procedure time was extended in the LAWT group than in the empirical group (mean 70.2 vs. 65.2 min, respectively).

CONCLUSION

The LAWT-guided energy titration strategy improved freedom from atrial arrhythmia recurrence, compared with conventional strategy.

Treatment of atrial fibrillation with second-generation cryoballoon followed by contact-sensing radiofrequency catheter ablation for arrhythmia recurrences-results of a 5-year follow-up

INTRODUCTION

The aim of this study was to report the long-term follow-up results of cryoballoon (CB) ablation in patients with atrial fibrillation.

METHODS

All consecutive patients who underwent second-generation CB ablation from February 2015 to December 2017 were included in our study. In all procedures, we used a 28-mm CB placed via a single transseptal puncture guided by intracardiac ultrasound. A 20-mm octapolar intraluminal circular catheter was used for intracardiac recordings. A single 180-s freeze strategy was employed. Repeated procedures were performed with a 3D mapping system and radiofrequency catheters.

RESULTS

A total of 126 patients (69.8% male, mean age 57 ± 11 years), of which 77.0% had paroxysmal atrial fibrillation (PAF), were included in the study. After a 5-year period, 52.4% of patients were in sinus rhythm without AF recurrence, off antiarrhythmic drugs. A total of 61.9% of patients were free of AF recurrence when redo PVI procedures were performed. When accounting for redo pulmonary vein isolation and antiarrhythmic drugs, a total of 73.8% of the patients were without AF recurrence in long-term follow-up. The patients who underwent redo pulmonary vein isolation procedures had statistically significant lower rates of AF recurrence (p = 0.006). In patients with PAF, long-term success rates improved from 62.9 to 79.4% for patients who underwent the redo procedure (p = 0.020). In patients with persistent atrial fibrillation (PersAF), success rates went up from 41.4 to 55.1% for patients with single or repeated PVI procedure (p = 0.071). In the whole cohort, a total of 3 (2.4%) procedure-related major complications occurred which included persistent PNP, arterial pseudoaneurysm, and arteriovenous fistula.

CONCLUSION

Our data suggest a favorable long-term safety and efficacy profile of second-generation CB ablation. In the mixed paroxysmal and persistent population, up to 73.8% of patients remained free of AF recurrence in the 5-year follow-up, when accounting for redo procedures and AADs. Only 2.4% of patients experienced major complications of the ablation procedure, none with permanent sequelae.

The safety and efficacy of third- and fourth-generation cryoballoons for atrial fibrillation: a systematic review and meta-analysis

Objectives

An increasing number of studies have shown that third (CB3)- and fourth-generation cryoballoons (CB4) have been used to treat various types of atrial fibrillation (AF), but previous research regarding the safety and efficacy of CB3 or CB4 ablation remains controversial. Therefore, a meta-analysis was performed to further evaluate the safety and efficacy of pulmonary vein isolation (PVI) using the CB3 and CB4 in the treatment of AF.

Methods

We searched PubMed, the Cochrane Library, Web of Science, China National Knowledge Infrastructure, Wanfang, China Science and Technology Journal Database, and Clinicaltrials.gov up to December 2023 for qualified trials and data extraction according to inclusion and exclusion criteria. All analyses were carried out using Review Manager 5.3 software.

Results

The meta-analysis included 13 observational studies consisting of 3,281 subjects and did not include a randomized controlled trial. Overall analyses indicated that the CB3 significantly reduced total procedure time [weighted mean difference (WMD) = -8.69 min, 95% confidence interval (CI) = -15.45 to -1.94 min, I2 = 93%], increased the PVI recording [relative risk (RR) = 1.24, 95% CI = 1.03-1.49, I2 = 90%], and increased the mean nadir temperature of overall PVs (WMD = 2.80°C, 95% CI = 1.08-4.51°C, I2 = 89%) compared with the CB2. Moreover, the CB4 significantly reduced the total procedure time (WMD = -14.50 min, 95% CI = -20.89 to -8.11 min, I2 = 95%), reduced the fluoroscopy time (WMD = -2.37 min, 95% CI = -4.28 to -0.46 min, I2 = 95%), increased the PVI recording (RR = 1.40, 95% CI = 1.15-1.71, I2 = 90%) compared with the CB2. Time-to-isolation, the success rate of PVI, AF recurrence, and complications in the CB3 and CB4 were not significantly different compared with the CB2.

Conclusion

These findings demonstrated that the CB3 and CB4 tended to be more effective than the CB2 in the treatment of AF, with shorter procedure times, more PVI recording, and similar safety endpoints.

PolarX vs Arctic Front for Cryoballoon Ablation of Paroxysmal AF: The Randomized COMPARE CRYO Study

BACKGROUND

Pulmonary vein isolation is an effective treatment for atrial fibrillation (AF). Cryoballoon ablation using the Arctic Front cryoballoon (Medtronic) was found to be superior to antiarrhythmic drug treatment. Recently, a novel cryoballoon system was introduced (PolarX, Boston Scientific).

OBJECTIVES

The purpose of this study was to compare the efficacy and safety of the 2 cryoballoons in a randomized controlled trial.

METHODS

Patients with symptomatic paroxysmal AF were enrolled in 2 centers and randomized 1:1 to pulmonary vein isolation using the PolarX or the Arctic Front cryoballoon. All patients received an implantable cardiac monitor. The primary endpoint was first recurrence of atrial tachyarrhythmia (AF, atrial flutter, or atrial tachycardia [AT]) between days 91 and 365. Procedural safety was assessed by a composite of tamponade, phrenic nerve palsy lasting >24 hours, vascular complications, stroke/transient ischemic attack, atrioesophageal fistula or death up to 30 days.

RESULTS

A total of 201 patients were enrolled. At 1 year, recurrence of atrial tachyarrhythmia had occurred in 41 of 99 patients (41.6%) assigned to the PolarX group and in 48 of 102 patients (47.1%) assigned to the Arctic Front group (HR: 0.85 [95% CI: 0.56-1.30]; P = 0.03 for noninferiority; P = 0.46 for superiority). The safety endpoint occurred in 5 patients (5%) in the PolarX group (n = 5 phrenic nerve palsies lasting >24 hours), whereas no safety endpoints occurred in the Arctic Front group (P = 0.03).

CONCLUSIONS

In this randomized controlled trial using implantable cardiac monitors for continuous rhythm monitoring, the novel PolarX cryoballoon was noninferior compared with the Arctic Front cryoballoon regarding efficacy. However, the PolarX balloon resulted in significantly more phrenic nerve palsies. (Comparison of PolarX and the Arctic Front Cryoballoons for PVI in Patients With Symptomatic Paroxysmal AF [COMPARE-CRYO]; NCT04704986).

One-year outcomes of pulmonary vein isolation with a novel cryoballoon: Primary results of the FROZEN AF trial

INTRODUCTION

Cryoablation therapy for pulmonary vein isolation (PVI) to treat paroxysmal atrial fibrillation (PAF) is well established. A novel 28 mm cryoballoon system designed to operate under low pressure to safely reach a lower nadir temperature and maintain constant balloon size during cooling has not been prospectively studied in a large patient population for safety and efficacy. The FROZEN AF (NCT04133168) trial was an international multicenter, open-label, prospective, single-arm study on the safety and performance of a novel cryoballoon system for treatment of PAF.

METHODS AND RESULTS

The study enrolled patients at 44 sites in 10 countries across North America, Europe, and Asia. Subjects were indicated for PVI treatment of PAF and had failed or were intolerant of one or more antiarrhythmic drugs. Procedural outcomes were defined based on the 2017 HRS consensus statement. Follow-up was performed at 7 days, 3, 6, and 12 months. Data are reported as mean ± SD or median (IQR). PVI was performed with a 28 mm cryoballoon in 325 drug refractory PAF patients. Complete PVI was achieved in 95.7% of patients. In cryoablation lesions longer than 60 s, 60.1% of PV isolations required only a single cryoballoon application. Procedure related complications included: phrenic nerve palsy [temporary 4 (1.2%), persistent 0 (0.0%)], cardiac tamponade/perforation 2 (0.6%), and air embolism 1 (0.3%). Freedom from documented atrial arrhythmia recurrence at 12 months was 79.9% (AF 82.7%, AFL 96.5%, AT 98.1%), antiarrhythmic drugs (AAD) were continued or re-initiated in 26.8% of patients after the 3-month blanking period. Additionally, an extension arm enrolled 50 pts for treatment with 28/31 mm variable size cryoballoon. A single temporary PNP occurred in this group, which resolved before discharge. Freedom from documented recurrence at 12 months in these pts was 82.0%.

CONCLUSIONS

This novel cryoballoon may facilitate PVI to treat PAF, providing more options to address the variety of anatomies present in patients with PAF. This cryoballoon system proved to be safe and effective for treatment of patients with drug refractory or drug intolerant PAF.

Incidence of phrenic nerve injury during pulmonary vein isolation using different cryoballoons: data from a large prospective ablation registry

AIMS

Phrenic nerve injury (PNI) is the most common complication during cryoballoon ablation. Currently, two cryoballoon systems are available, yet the difference is unclear. We sought to compare the acute procedural efficacy and safety of the two cryoballoons.

METHODS

This prospective observational study consisted of 2,555 consecutive atrial fibrillation (AF) patients undergoing pulmonary vein isolation (PVI) using either conventional (Arctic Front Advance) (AFA-CB) or novel cryoballoons (POLARx) (POLARx-CB) at 19 centers between January 2022 and October 2023.

RESULTS

Among 2,555 patients (68.8 ± 10.9 years, 1,740 men, paroxysmal AF[PAF] 1,670 patients), PVIs were performed by the AFA-CB and POLARx-CB in 1,358 and 1,197 patients, respectively. Touch-up ablation was required in 299(11.7%) patients. The touch-up rate was significantly lower for POLARx-CB than AFA-CB (9.5% vs. 13.6%, p = 0.002), especially for right inferior PVs (RIPVs). The touch-up rate was significantly lower for PAF than non-PAF (8.8% vs. 17.2%, P < 0.001) and was similar between the two cryoballoons in non-PAF patients. Right PNI occurred in 64(2.5%) patients and 22(0.9%) were symptomatic. It occurred during the right superior PV (RSPV) ablation in 39(1.5%) patients. The incidence was significantly higher for POLARx-CB than AFA-CB (3.8% vs. 1.3%, P < 0.001) as was the incidence of symptomatic PNI (1.7% vs. 0.1%, P < 0.001). The difference was significant during RSPV (2.5% vs. 0.7%, P < 0.001) but not RIPV ablation. The PNI recovered more quickly for the AFA-CB than POLARx-CB.

CONCLUSIONS

Our study demonstrated a significantly higher incidence of right PNI and lower touch-up rate for the POLARx-CB than AFA-CB in the real-world clinical practice.

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.

Durability of pulmonary vein isolation for atrial fibrillation: a meta-analysis and systematic review

AIMS

Pulmonary vein isolation (PVI) plays a central role in the interventional treatment of atrial fibrillation (AF). Uncertainties remain about the durability of ablation lesions from different energy sources. We aimed to systematically review the durability of ablation lesions associated with various PVI-techniques using different energy sources for the treatment of AF.

METHODS AND RESULTS

Structured systematic database search for articles published between January 2010 and January 2023 reporting PVI-lesion durability as evaluated in the overall cohort through repeat invasive remapping during follow-up. Studies evaluating only a proportion of the initial cohort in redo procedures were excluded. A total of 19 studies investigating 1050 patients (mean age 60 years, 31% women, time to remap 2-7 months) were included. In a pooled analysis, 99.7% of the PVs and 99.4% of patients were successfully ablated at baseline and 75.5% of the PVs remained isolated and 51% of the patients had all PVs persistently isolated at follow-up across all energy sources. In a pooled analysis of the percentages of PVs durably isolated during follow-up, the estimates of RFA were the lowest of all energy sources at 71% (95% CI 69-73, 11 studies), but comparable with cryoballoon (79%, 95%CI 74-83, 3 studies). Higher durability percentages were reported in PVs ablated with laser-balloon (84%, 95%CI 78-89, one study) and PFA (87%, 95%CI 84-90, 2 studies).

CONCLUSION

We observed no significant difference in the durability of the ablation lesions of the four evaluated energies after adjusting for procedural and baseline populational characteristics.

Comparison of the PolarX and the Arctic Front cryoballoon for pulmonary vein isolation in patients with symptomatic paroxysmal atrial fibrillation (COMPARE CRYO) - Study protocol for a randomized controlled trial

INTRODUCTION

Single-shot devices are increasingly used for pulmonary vein isolation (PVI) in atrial fibrillation (AF). The Arctic Front cryoballoon (Medtronic) is the most frequently used single-shot technology. A recently developed novel cryoballoon has been introduced (PolarX, Boston Scientific) with the aim to address limitations of the Arctic Front system.

METHODS

COMPARE CRYO is a multicentre, randomized, controlled trial with blinded endpoint adjudication by an independent clinical events committee. A total of 200 patients with paroxysmal AF undergoing their first PVI are randomized 1:1 between PolarX cryoballoon ablation and Arctic Front cryoballoon ablation. Continuous monitoring during follow-up is performed using an implantable cardiac monitor (ICM) in all patients. The primary endpoint is time to first recurrence of any atrial tachyarrhythmia (AF, atrial flutter, and/or atrial tachycardia) ≥ 120 s between days 91 and 365 post ablation as detected on the (ICM). Procedural safety is assessed by a composite of cardiac tamponade, persistent phrenic nerve palsy >24 h, vascular complications requiring intervention, stroke/transient ischemic attack, atrioesophageal fistula or death occurring during or up to 30 days after the procedure. Key secondary endpoints include (1) procedure and fluoroscopy times, (2) AF burden, (3) proportion of patients with recurrence in the blanking period, (4) proportion of patients undergoing repeat ablation, and (5) quality of life changes at 12 months compared to baseline.

CONCLUSION

COMPARE CRYO will compare the efficacy and safety of the novel PolarX cryoballoon and the standard-of-practice Arctic Front cryoballoon for first PVI performed in patients with symptomatic paroxysmal AF.

TRIAL REGISTRATION

(ClinicalTrials.gov ID: NCT04704986).

Procedural performance between two cryoballoon systems for ablation of atrial fibrillation depends on pulmonary vein anatomy

Background

Cryoballoon ablation is a first-line therapy for atrial fibrillation. We compared the efficacy and safety of two ablation systems and addressed the influence of pulmonary vein (PV) anatomy on performance and outcome.

Methods

We consecutively enrolled 122 patients who were planned for first-time cryoballoon ablation. Patients were assigned 1:1 for ablation with the POLARx or the Arctic Front Advance Pro (AFAP) system and followed-up for 12 months. Procedural parameters were recorded during the ablation. Before the procedure, a magnetic resonance angiography (MRA) of the PVs was generated and diameter, area, and shape of each PV ostium were assessed. We applied an evaluated PV anatomical scoring system on our MRA measurement data ranging from 0 (best anatomical combination) to 5.

Results

Procedures performed with POLARx were associated with shorter time to balloon temperature -30°C (p < .001), lower balloon nadir temperature (p < .001), and longer thawing time till 0°C (p < .001) in all PVs, however, time to isolation was similar. We observed a decreasing performance with each increase in the score for the AFAP, whereas the POLARx performed constant regardless of the score. At 1 year, AF recurred in 14 of 44 patients treated with AFAP (31.8%) and in 10 of 45 patients treated with POLARx (22.2%) (hazard ratio, 0.61; 95% CI 0.28 to 1.37; p = .225). There was no significant correlation between PV anatomy and clinical outcome.

Conclusion

We found significant differences in cooling kinetics, especially when anatomical conditions are difficult. However, both systems have a comparable outcome and safety profile.

Acute procedural efficacy and safety of a novel cryoballoon for the treatment of paroxysmal atrial fibrillation: Results from the POLAR ICE study

INTRODUCTION

Pulmonary vein isolation (PVI) is well established as a primary treatment for atrial fibrillation (AF). The POLAR ICE study was designed to collect prospective real world data on the safety and effectiveness of the POLARxTM cryoballoon for PVI to treat paroxysmal AF.

METHODS

POLAR ICE, a prospective, non-randomized, multicenter (international) registry (NCT04250714), enrolled 399 patients across 19 European centers. Procedural characteristics, such as time to isolation, cryoablations per pulmonary vein (PV), balloon nadir temperature, and occlusion grade were recorded. PVI was confirmed with entrance block testing.

RESULTS

Data on 372 de novo PVI procedures (n = 2190 ablations) were collected. Complete PVI was achieved in 96.8% of PVs. Procedure and fluoroscopy times were 68.2 ± 24.6 and 15.6 ± 9.6 min, respectively. Left atrial dwell time was 46.6 ± 18.3 min. Grade 3 or 4 occlusion was achieved in 98.2% of PVs reported and 71.2% of PVs isolation required only a single cryoablation. Of 2190 cryoapplications, 83% had a duration of at least 120 s; nadir temperature of these ablations averaged -56.3 ± 6.5°C. There were 6 phrenic nerve palsy events, 2 of which resolved within 3 months of the procedure.

CONCLUSION

This real-world usage data on a novel cryoballoon suggests this device is effective, safe, and relatively fast in centers with cryoballoon experience. These data are comparable to prior POLARx reports and in keeping with reported data on other cryoballoons. Future studies should examine the long-term outcomes and the relationship between biophysical parameters and outcomes for this novel cryoballoon.

Efficacy and safety of a novel cryoballoon ablation system: multicentre comparison of 1-year outcome

AIMS

The aim of the study was to compare the 1-year efficacy and safety of a novel cryoballoon (NCB) ablation system (POLARx; Boston Scientific) for pulmonary vein isolation (PVI) compared with the standard cryoballoon (SCB) system (Arctic Front, Medtronic).

METHODS AND RESULTS

Consecutive patients with atrial fibrillation (AF) undergoing PVI using the NCB and the SCB at two centres were included. We report 1-year efficacy after 12 months, short-term safety and hospitalizations within the blanking period, and predictors for AF recurrence. In case of repeat procedures, pulmonary vein (PV) reconnection patterns were characterized. Eighty patients (age 66 ± 10 years, ejection fraction 57 ± 10%, left atrial volume index 39 ± 13 mL/m2, paroxysmal AF in 64%) were studied. After a single procedure and a follow-up of 12 months, 68% in the NCB group and 70% in the SCB group showed no recurrence of AF/atrial tachycardias (P = 0.422). One patient in the NCB group suffered a periprocedural stroke with full recovery. There were no differences regarding hospitalizations during follow-up between the groups. PV reconnection observed during 12 repeat procedures (4 NCB, 8 SCB) pattern was comparable between the groups with more reconnections in the right-sided compared with the left-sided PVs.

CONCLUSION

In this multicentre study comparing two currently available cryoballoon ablation systems for PVI, no differences were observed in the efficacy and safety during a follow-up of 12 months.

A novel alternating second-generation cryoballoon or contact-force guided radiofrequency catheter ablation strategy for redo-ablation in patients with recurrent atrial fibrillation: a single-center experience

BACKGROUND

Pulmonary vein (PV) reconnection after radiofrequency (RFC) or cryoballoon (CB) pulmonary vein isolation (PVI) is common.

METHOD

We report a single-center experience of 156 patients who underwent a redo procedure-ablation strategy for recurrent atrial fibrillation (AF) in a reverse sequence after a failed index RFC or CB PVI.

RESULTS

A total of 60 patients after index CB PVI underwent RFC-redo ablation (CB-RFC redo), and 96 patients after index RFC PVI underwent CB-redo ablation (RFC-CB redo). During the redo procedure, the proportion of patients with PV reconnection was lower after index CB PVI procedure compared with the proportion of patients after index RFC PVI (88.3% versus 98.9%, p = 0.01). Additionally, a mean number of 1.50 ± 0.8 PVs/patient were reconnected after index CB PVI, compared with 3.36 ± 0.9 PVs/patient after index RFC PVI (p = 0.001). Patients after index RFC PVI frequently presented with ≥ 3 reconnected PVs, compared with index CB PVI (70.8% vs 10%, p < 0.001). At a 2-year follow-up, 43 patients (27.6%) developed recurrence after redo ablation, with a similar AF-free outcome (CB-RFC redo:73.3% vs RFC-CB redo: 71.9%, p = 0.873). In the multivariate analysis, persistent AF (HR = 2.107, 95% CI: 1.085-4.091, p = 0.028) and early AF recurrence after the initial ablation (HR = 2.431, 95% CI: 1.279-4.618, p = 0.007) were independent predictors of AF recurrence.

CONCLUSIONS

The extent and distribution of PV reconnections were different after index RFC and CB PVI procedures. Alternating CB or RFC ablation technique strategy is effective with a similar long-term outcome, and it may be an appropriate option for repeated AF ablation.

Ultra-high-resolution assessment of lesion extension after cryoballoon ablation for pulmonary vein isolation

INTRODUCTION

Unrecognized incomplete pulmonary vein (PV) isolation during the index procedure, can be a major cause of clinical recurrences of atrial fibrillation (AF) after cryoballoon (CB) ablation. We aimed to characterize the extension of the lesions produced by CB ablation and to assess the value of using an ultra-high resolution electroanatomic mapping (UHDM) system to detect incomplete CB lesions.

MATERIALS AND METHODS

Twenty-nine consecutive patients from the CHARISMA registry undergoing AF ablation at four Italian centers were prospectively evaluated. The Rhythmia™ mapping system and the Orion™ (Boston Scientific) mapping catheter were used to systematically map the left atrium and PVs before and after cryoablation.

RESULTS

A total of 116 PVs were targeted and isolated. Quantitative assessment of the lesions revealed a significant reduction of the antral surface area of the PV, resulting in an ablated area of 5.7 ± 0.7 cm2 and 5.1 ± 0.8 cm2 for the left PV pair and right PV pair, respectively (p = 0.0068). The mean posterior wall (PW) area was 22.9 ± 2 cm2 and, following PV isolation, 44.8 ± 6% of the PW area was ablated. After CB ablation, complete isolation of each PV was documented by the POLARMap™ catheter in all patients. By contrast, confirmatory UHDM and the Lumipoint™ tool unveiled PV signals in 1 out of 114 of the PVs (0.9%). Over 30-day follow-up, no major procedure-related adverse events were reported. After a mean follow-up of 333 days, 89.7% of patients were free from arrhythmia recurrence.

CONCLUSION

The lesion extension achieved by the new CB ablation system involved the PV antrum, with less than 50% of the PW remaining untouched. The new system, with short tip and circular mapping catheter, failed to achieve PV isolation in only 0.9% of all PVs treated.

CLINICAL TRIAL REGISTRATION

[http://clinicaltrials.gov/], identifier [NCT03793998].

Comparison of the acute outcome of two cryoballoon technologies for pulmonary vein isolation: An updated systematic review and meta-analysis

Initial experience suggests that the POLARx cryoballoon system (Boston Scientific) has a similar procedural efficacy and safety as Arctic Front Advance Pro (AFA-Pro, Medtronic). We performed an updated systematic review and meta-analysis comparing POLARx and AFA-Pro. Embase, MEDLINE, Web of Science, Cochrane, and Google Scholar databases were searched until 12/01/2022 for studies comparing POLARx versus AFA-Pro in patients undergoing pulmonary vein (PV) isolation for AF. A total of 8 studies, involving 1146 patients from 11 European centers were included (POLARx n = 317; AFA-Pro n = 819). There were no differences in acute PV isolation, procedure time, fluoroscopy time, ablation time, minimal esophageal temperature, and risk of phrenic nerve palsy or thromboembolic events. Balloon nadir temperatures were lower for POLARx in all PVs. Compared with AFA-Pro, POLARx had a higher rate of first freeze isolation in the left inferior PV (LIPV) (odds ratio [OR]: 2.60; 95 % confidence interval [CI]: 1.06 to 6.43; P = 0.04), higher likelihood of time-to-isolation (TTI) recording in LIPV (OR: 2.91; 95 % CI: 1.54 to 5.49; P = 0.001) and right inferior PV (OR: 3.23; 95 % CI: 1.35 to 7.74; P = 0.008). In contrast, the TTI in LIPV was longer with POLARx in comparison to AFA-Pro (mean difference: 7.61 sec; 95 % CI 2.43 to 12.8 sec; P = 0.004). In conclusion, POLARx and AFA-Pro have a similar acute outcome. Interestingly, there was a higher rate of TTI recording in the inferior PVs with POLARx. This updated meta-analysis provides new safety data on esophageal temperature and thromboembolic events.

Impact of pulmonary vein variant anatomy and cross-sectional orifice area on freedom from atrial fibrillation recurrence after cryothermal single-shot guided pulmonary vein isolation

BACKGROUND

Cryoballoon (CB)-guided pulmonary vein isolation (PVI) is an established treatment for atrial fibrillation (AF). This study aimed to evaluate ablation efficacy and freedom from arrhythmia recurrence using the novel POLARx compared to the Arctic Front Advance Pro (AFA) CB system including the analysis of individual PV characteristics.

METHODS

A total of 687 patients underwent CB-guided ablation for AF. Arrhythmia recurrence was defined as an ECG documented episode of any AF/atrial tachycardia (AT) > 30 s. Anatomical characteristics were assessed using magnetic resonance imaging (MRI). For each PV, the cross-sectional orifice area (CSOA) was determined. Follow-up examinations were scheduled after 3, 6, and 12 months.

RESULTS

Acute PVI was achieved in all patients. Twelve-month AF-free survival was similar between the groups (POLARx 43/86 (50%) vs. AFA 318/601 (53%), Log-rank (LR) p = 0.346). MRI found a comparable percentage of patients with normal PV anatomy (POLARx 71/86 (83%) vs. AFA 530/601 (85%), p = 0.162). Patients with variant PV characteristics presented with a significantly impaired 12-month AF-free survival (normal PVs 326/585 (56%) vs. variant PVs 27/102 (27%), LR p < 0.001) independent of the applied CB ablation system. PAF patients with AF recurrence presented with significantly larger CSOA of the left-sided PVs and the right superior PVs (LSPV: p < 0.001; LIPV: p < 0.001; RSPV: p < 0.001). In PERS AF, no association between CSOA and ablation outcome was observed. Multivariate analyses identified PERS AF (hazard ratio (HR) 2.504, confidence interval (CI), 1.900-3.299, p < 0.001) and variant PV anatomy (HR 2.124, CI 1.608-2.805, p < 0.001) as independent predictors for AF recurrence.

CONCLUSIONS

Both CB ablation systems are associated with comparable 12-month AF-free survival rates. Variant PV anatomy seems to be predictive for AF recurrence. An association between CSOA and the outcome after CB-guided PVI was demonstrated for PAF.

News from the Cold Chamber: Clinical Experiences of POLARx versus Arctic Front Advance for Single-Shot Pulmonary Vein Isolation

Cryoballoon (CB)-guided pulmonary vein isolation (PVI) represents a cornerstone in the treatment of atrial fibrillation (AF). Recently, a novel balloon-guided single shot device (POLARx, Boston Scientific) was designed. Our study aimed to compare the efficacy, safety and characteristics of the novel CB system with the established one (Arctic Front Advance (Pro), AFA, Medtronic). A total number of 596 patients undergoing CB-guided ablation for AF were included. 65 patients (65.0 ± 11.6, 31% female) undergoing PVI with the POLARx were compared to a cohort of 531 consecutive patients (63.0 ± 27.9, 25% female) treated with AFA. Acute PVI was achieved in all patients (n = 596, 100%). Total procedure duration (POLARx 113.3 ± 23.2 min, AFA 100.9 ± 21.3 min; p < 0.001) and fluoroscopy time (POLARx 10.5 ± 5.9 min, AFA 4.8 ± 3.6 min; p < 0.001) were significantly longer in the POLARx group. The POLARx balloon achieved significantly lower nadir temperatures (POLARx −57.7 ± 0.9 °C, AFA −45.1 ± 2.6 °C; p < 0.001) and a significantly higher percentage of pulmonary veins successfully isolated with the first freeze (p = 0.027 *). One major complication occurred in the POLARx (2%) and three (1%) in the AFA group. Both ablation systems are comparably safe and effective. AF ablation utilizing the POLARx system is associated with longer procedure and fluoroscopy times as well as lower nadir temperatures.

Novel cryoballoon to isolate pulmonary veins in patients with paroxysmal atrial fibrillation: long-term outcomes in a multicentre clinical study

BACKGROUND

Recently, a novel cryoballoon ablation catheter has demonstrated acute safety and efficacy in de novo pulmonary vein isolation (PVI) procedures in patients with paroxysmal atrial fibrillation (PAF). However, there are limited studies demonstrating the long-term efficacy. The aim of this study was to evaluate the long-term safety and efficacy of this novel cryoballoon in treating PAF.

METHODS

This was a non-randomized, prospective, multicentre study enrolling 58 consecutive patients. Cryoablation was delivered for 180 s if time to isolation was ≤ 60 s. Otherwise a 240-s cryoablation was performed. One centre performed pre- and post-ablation high-density mapping (n = 9) to characterize lesion formation. After a 3-month blanking period, recurrence was defined as having any documented, symptomatic episode(s) of AF or atrial tachycardia. All patients were followed for 1 year.

RESULTS

Acute PVI was achieved in 230 of 231 pulmonary veins (99.6%) with 5.3 ± 1.6 cryoablations per patient (1.3 ± 0.7 cryoablations per vein). Forty-three (77%) patients remained arrhythmia-free at 1-year follow-up. Four patients (6.9%) experienced phrenic nerve injury (3 resolved during the index procedure; 1 resolved at 6 months). One serious adverse device event was reported: femoral arterial embolism event occurring 2 weeks post-index procedure. For patients who underwent high-density mapping, cryoablation was antral with 50% of the posterior wall ablated.

CONCLUSIONS

Initial multicentre clinical experience with a novel cryoballoon has demonstrated safety and efficacy of PVI in patients with PAF. Ablation with this cryoballoon provides a wide, antral lesion set with significant debulking of the posterior wall of the left atrium.

A tale of two balloons: technical and procedural difference between cryoballoon systems

PURPOSE OF REVIEW

The cryoballoon catheter has been an option for the treatment of atrial fibrillation for over a decade. The most widely used device is the Medtronic Arctic Advance cryoballoon catheter. Recently, Boston Scientific has released the POLARx cryoballoon catheter. Here we review the major changes in the catheter system's design and its implications for procedural practice.

RECENT FINDINGS

The POLARx cryoballoon catheter has been approved for use in Europe. Some studies have been published detailing the first clinical experiences in vivo with this newest technology.

SUMMARY

The changes to the POLARx cryoballoon catheter, particularly its ability to maintain balloon size and pressure, will improve occlusion and theoretically improve procedural outcomes.

Comparison of procedural efficacy, balloon nadir temperature, and incidence of phrenic nerve palsy between two cryoballoon technologies for pulmonary vein isolation: A systematic review and meta-analysis

Introduction

In May 2020, a novel cryoballoon system (POLARx; Boston Scientific) became available for catheter ablation of atrial fibrillation (AF). The design of the cryoballoon is comparable to the Arctic Front Advance Pro (AFA‐Pro; Medtronic), but it is more compliant during freezing. We compared the procedural efficacy, biophysical parameters, and risk of phrenic nerve palsy (PNP) between the two cryoballoons.

Methods

Embase, MEDLINE, Web of Science, Cochrane, and Google Scholar databases were searched until June 1, 2021 for relevant studies comparing POLARx versus AFA‐Pro in patients undergoing pulmonary vein isolation (PVI) for AF.

Results

A total of four studies, involving 310 patients were included. There was no difference between the two groups for outcomes regarding procedural efficacy: acute PVI (odds ratio [OR]: 0.43; 95% confidence interval [CI]: 0.06 to 3.03; p = .40), procedure time (mean difference [MD]: 8.15 min; 95% CI: −8.09 to 24.39; p = .33), fluoroscopy time (MD: 1.32 min; 95% CI: −1.61 to 4.25; p = .38) and ablation time (MD: 1.00 min; 95% CI: −0.20 to 2.20; p = .10). The balloon nadir temperature was lower for all individual pulmonary veins (PV) in POLARx compared with AFA‐Pro (MD: −9.74°C, −9.98°C, −6.72°C, −7.76°C, for left superior PV, left inferior PV, right superior PV, and right inferior PV, respectively; all p < .001). The incidence of PNP was similar between groups (OR: 0.79; 95% CI: 0.22 to 2.85; p = .72).

Conclusion

In AF patients undergoing PVI, POLARx and AFA‐Pro had a similar procedural efficacy. Balloon nadir temperatures were lower with POLARx, however, the incidence of PNP was similar.