Durability of Pulmonary Vein Isolation with Cryoballoon Ablation: Results from the Sustained PV Isolation with Arctic Front Advance (SUPIR) Study

Catheters and Tools with Pulsed Field Ablation-Pulmonary Vein Isolation with Focal Lattice-Tip Affera Sphere 9

The Affera system features a versatile and large footprint catheter with a lattice-tip design that is capable of delivering both pulsed field and radiofrequency energy. It provides precise mapping and ablation capabilities, demonstrating high acute success rates and durable lesion formation, with excellent safety profile in both radiofrequency and pulsed field ablation modes. Preclinical and clinical studies have shown high lesion durability, reduced procedural time, and promising outcomes in pulmonary vein isolation with minimal complications.

PVI With CF-Sensing Large-Tip Focal PFA Catheter With 3D Mapping for Paroxysmal AF: Omny-IRE 3-Month Results

BACKGROUND

Omny-IRE (A Study For Treatment of Paroxysmal Atrial Fibrillation [PAF] With the OMNYPULSE Catheter and the TRUPULSE Generator; NCT05971693) evaluated safety and effectiveness of a novel large-tip focal, multielectrode, contact force-sensing, pulsed field ablation catheter with electroanatomic mapping integration.

OBJECTIVES

This study sought to assess 3-month safety and effectiveness of the platform for treating symptomatic paroxysmal atrial fibrillation.

METHODS

Pulmonary vein isolation (PVI) was performed using the OMNYPULSE Platform. Primary effectiveness was adenosine/isoproterenol-proof entrance block. Primary safety was occurrence of primary adverse events. Prespecified patient subsets underwent systematic brain imaging, esophageal endoscopy, cardiac computed tomography/magnetic resonance angiogram, and mandatory 3-month remapping for PVI durability assessment.

RESULTS

Of 188 patients enrolled, 136 were included in the per-protocol analysis. Primary effectiveness was 100% (136 of 136). Median (Q1-Q3) procedure, left atrial dwell, total ablation, and total fluoroscopy times were 105.5 (91.0-124.0), 70.0 (56.0-81.5), 46.9 (37.1-58.8), and 5.0 (3.1-9.8) minutes, respectively. The primary adverse event rate was 3.0% (4 of 135 patients with 3-month follow-up; 3 major vascular access complications, 1 pericarditis). Brain imaging (n = 30) revealed 1 patient (3.3%) with an asymptomatic silent cerebral event at discharge, which resolved at 1 month without neurological change. No esophageal injury was observed. Computed tomography/magnetic resonance angiogram imaging (n = 24) showed no incidences of pulmonary vein narrowing >70%. During remapping, PVI was durable in 84.5% (98 of 116) of veins and 62.1% (18 of 29) of patients. With an optimized workflow, PVI durability improved to 89.3% (75 of 84) and 71.4% (15 of 21) of veins and patients, respectively.

CONCLUSIONS

The force-sensing, large-focal pulsed field ablation catheter with 3-dimensional electroanatomic mapping integration showed 100% acute success with a promising safety profile for treating paroxysmal atrial fibrillation. Prespecified remapping showed good PVI durability. (A Study For Treatment of Paroxysmal Atrial Fibrillation [PAF] With the OMNYPULSE Catheter and the TRUPULSE Generator; NCT05971693).

Pulmonary vein isolation durability with fluoroscopy or 3D mapping-guided radiofrequency balloon ablation: a mandated remap study

Background

Effective balloon positionnking during pulmonary vein isolation (PVI) with a radiofrequency balloon (RFB) is crucial for optimal energy delivery, maximising lesion formation, and preventing gaps. Traditionally, fluoroscopy is used to guide pulmonary vein (PV) occlusion, however, this method exposes patients to radiation. Recently, RFBs equipped with 3D electroanatomical mapping (EAM) offer an alternative approach, potentially achieving the same results with reduced radiation exposure. Our main aim was to evaluate procedural characteristics, such as acute isolation and time-to-isolation (TTI), when the RFB is positioned based only on fluoroscopy feedback vs. fluoroscopy and a 3D-EAM. The secondary objective was to assess PVI durability through mandated remapping in asymptomatic patients from both groups.

Methods

A total of 60 patients were enrolled and underwent either a fluoroscopy-guided (FLUO, 30 patients) or fluoroscopy + 3D-EAM (3D-MAP, 30 patients) ablation. In each group, 15 patients without any documented recurrence underwent protocol-mandated repeat 3D-EAM six months after the index ablation. Procedural outcomes, lesion metrics, and safety profiles were assessed and compared between groups.

Results

At a median follow-up of 579 days, freedom from any atrial tachyarrhythmias (ATAs) was 89.7% in the FLUO group and 92.3% in the 3D-EAM group (P > 0.05). The latter was associated with significantly reduced fluoroscopy exposure (median 10.5 vs. 7.0 min, P < 0.005). Procedure time and efficacy metrics, including single-shot isolation rates and TTI, were comparable between groups. Durable PVI on a per PV basis was present in 54/60 (90%) vs. 57/60 (94%) of PVs in the FLUO and 3D-EAM groups, respectively (P = 0.9).

Conclusion

Radiofrequency balloon led to a high rate of durable PVI whether its guided by fluoroscopy only or 3D mapping. The latter allowed avoiding dye comsuption and a reduction of fluoroscopic times.

Efficacy, safety, and somatosensory comparison of pulsed-field ablation and thermal ablation: outcomes from a 2-year follow-up

BACKGROUND

Pulsed-field ablation (PFA), as a nonthermal ablative approach for atrial fibrillation, has attracted much attention in recent years. And there are few comparative studies on PFA versus conventional thermal ablation, including radiofrequency ablation (RFA) and cryoballoon ablation (CBA). The efficacy, safety, and somatic sensation of PFA and thermal ablation need to be further compared.

METHODS

A total of 109 patients with paroxysmal atrial fibrillation were divided into three groups (27 in the PFA group, 41 in the CBA group, and 41 in the RFA group), and the operation characteristics, efficacy, safety, and somatic sensation were recorded and analyzed. All patients were followed for 2 years.

RESULTS

All pulmonary veins were successfully isolated except for 1 pulmonary vein that was not successfully isolated during the CBA process (PFA vs. CBA vs. RFA = 100% vs. 99% vs. 100%). The total operation time for PFA is considerably shorter than that for thermal ablation (PFA vs. CBA vs. RFA = 65.28 ± 22.78 min vs. 75.38 ± 18.53 min vs. 96.26 ± 23.23 min, P < 0.001), and the same applies to all the sub-phases. PFA was similarly more dominant in terms of somatosensory perception, mainly in headache (PFA vs. CBA = 1.17 ± 0.48 vs. 2.31 ± 1.06, P < 0.001) and chest pain (PFA vs. RFA = 1.45 ± 0.88 vs. 2.52 ± 1.06, P < 0.001). All these three groups demonstrated good maintenance rates (PFA vs. CBA vs. RFA = 85.00% vs. 80.49% vs. 78.05%, 2 years after operation).

CONCLUSION

PFA demonstrates its excellent somatic sensation and favorable safety. And it also showed a great immediate success and maintenance rate, which is not inferior to thermal ablation.

Durability of thermal pulmonary vein isolation in persistent atrial fibrillation assessed by mandated repeat invasive study

BACKGROUND

No study has assessed the durability of pulmonary vein isolation (PVI) with radiofrequency (RF) and cryoballoon (CB) in patients with persistent atrial fibrillation. These data are especially lacking for those with significantly diseased left atria (LA).

OBJECTIVES

The goals of this study were to assess PVI durability in patients with significant LA disease and to compare reconnection rates between RF and CB.

METHODS

Forty-four patients (mean age 63 years; 34 (77%) male; median time since atrial fibrillation diagnosis 22.5 months; median indexed LA volume 36 mL/m2) were randomized 1:1 to RF or CB PVI. A redo procedure using ultra-high-density electroanatomic mapping was mandated at 2 months, where PV reconnections were identified and reisolated.

RESULTS

Thirty-eight patients underwent both procedures (CB n = 17; RF n = 21). Index RF procedures were longer (median 158 minutes vs 97 minutes; P < .001) but required less fluoroscopy (9.5 minutes vs 23 minutes; P < .001). At the index RF procedure, a median of 47% of LA myocardium had voltage < 0.5 mV, suggesting that half of the mapped LA comprised scar. PV reconnection was observed in 73 of 152 PVs (48.0%) and was more frequent with CB (58.8%) than with RF (39.3%) (P = .022). Reconnection of at least 1 PV was detected in >75% of patients. Significantly more ablation was required during the redo procedure to reisolate PVs in the CB arm (median 10.8 minutes vs 1.2 minutes; P < .001).

CONCLUSION

PVI durability may be poor in those with significant LA scarring and dilatation, even with modern thermal ablation technologies. RF resulted in significantly better PVI durability than did CB in this complex population.

Modification of the pulmonary vein antrum is associated with recurrence after durable pulmonary vein isolation for paroxysmal atrial fibrillation

BACKGROUND

Although previous studies have shown the isolated areas after pulmonary vein isolation (PVI) using cryoballoons (CB) (CB-PVI), no studies have investigated the association between the isolated area and recurrence of atrial fibrillation (AF) and atrial tachycardia (AT). This single-center observational study investigated the association between the ablated area and recurrence rate after durable CB-PVI for paroxysmal AF.

METHODS

This study included 76 patients with paroxysmal AF who underwent CB-PVI and established durable PVI with a second procedure, regardless of AF/AT recurrence, 6 months after the first procedure. To compare the ablated zones, we quantified the left- and right-sided PV antral isolation areas and non-ablated posterior wall (PW) area. We examined non-ablated areas of the PW and AF/AT recurrence in the chronic phase.

RESULTS

In total, 16 of the 76 patients had AF/AT recurrence. The mean follow-up duration was 34 months. The non-ablated PW area (14.0 ± 4.6 cm2 vs. 11.5 ± 3.7 cm2; p = 0.0213) and the ratio of the non-ablated PW area to the whole PW area (NAPW) (52.9 ± 9.1% vs. 44.8 ± 9.8%; p = 0.003) were significantly higher in the AF/AT recurrence group than in the AF/AT non-recurrence group. NAPW > 50% was an independent predictor of AF/AT recurrence.

CONCLUSION

The NAPW after durable CB-PVI is associated with AF/AT recurrence. PW isolation or additional applications on the PV antrum with cryoballoon may be considered in addition to PVI in paroxysmal AF, especially in patients with dilated left atria.

Durability of CLOSE-Guided Pulmonary Vein Isolation in Persistent Atrial Fibrillation: A Prospective Remapping Study

BACKGROUND

Recurrence of paroxysmal atrial fibrillation (AF) following pulmonary vein isolation (PVI) is presumably caused by pulmonary vein (PV) reconnections. However, there is little data available on the durability of PVI and incidence of arrhythmia recurrence in patients with persistent AF.

OBJECTIVES

The purpose of this study was to evaluate the lesion durability by means of an a priori planned remapping procedure in patients with persistent AF undergoing CLOSE-guided PVI.

METHODS

In a prospective study, we included patients with symptomatic, persistent AF undergoing CLOSE-guided radiofrequency ablation. Irrespective of AF recurrence, a redo procedure was mandated 6 months following the index procedure to evaluate PV reconnections. The outcome of AF ablation was based on clinical recurrence and 7-day Holter electrocardiogram 3 and 6 months after the index procedure and 3, 6, and 12 months after the redo procedure.

RESULTS

Of 30 patients included, 26 (81% men; median age 68 years) underwent the planned remapping study a median of 6 months after the index procedure, whereas 4 patients without recurrence refused a repeat procedure. In total, 78 of 102 (76%) PVs showed durable isolation and 15 patients (58%) presented complete isolation of all PVs. Beyond the blanking period, 6 of 26 patients (23%) had arrhythmia recurrence before the redo procedure. Recurrence had occurred in 33% of patients with complete isolation of all veins and in 9% of patients with PV reconnections (P = 0.197). After re-PVI in patients with PV reconnections and additional ablation in patients with recurrence but durable PVI, 17 of 26 patients (65%) were free of arrhythmia after 12 months.

CONCLUSIONS

In patients with persistent AF, CLOSE-guided PVI resulted in durable rate of PVI on a per-vein and per-patient level of 76% and 58%, respectively. Arrhythmia recurrence was numerically higher in patients with durable PVI compared with patients without.

Validation of a machine learning algorithm to identify pulmonary vein isolation during ablation procedures for the treatment of atrial fibrillation: results of the PVISION study

AIMS

Pulmonary vein isolation (PVI) is the cornerstone of ablation for atrial fibrillation. Confirmation of PVI can be challenging due to the presence of far-field electrograms (EGMs) and sometimes requires additional pacing manoeuvres or mapping. This prospective multicentre study assessed the agreement between a previously trained automated algorithm designed to determine vein isolation status with expert opinion in a real-world clinical setting.

METHODS AND RESULTS

Consecutive patients scheduled for PVI were recruited at four centres. The ECGenius electrophysiology (EP) recording system (CathVision ApS, Copenhagen, Denmark) was connected in parallel with the existing system in the laboratory. Electrograms from a circular mapping catheter were annotated during sinus rhythm at baseline pre-ablation, time of isolation, and post-ablation. The ground truth for isolation status was based on operator opinion. The algorithm was applied to the collected PV signals off-line and compared with expert opinion. The primary endpoint was a sensitivity and specificity exceeding 80%. Overall, 498 EGMs (248 at baseline and 250 at PVI) with 5473 individual PV beats from 89 patients (32 females, 62 ± 12 years) were analysed. The algorithm performance reached an area under the curve (AUC) of 92% and met the primary study endpoint with a sensitivity and specificity of 86 and 87%, respectively (P = 0.005; P = 0.004). The algorithm had an accuracy rate of 87% in classifying the time of isolation.

CONCLUSION

This study validated an automated algorithm using machine learning to assess the isolation status of pulmonary veins in patients undergoing PVI with different ablation modalities. The algorithm reached an AUC of 92%, with both sensitivity and specificity exceeding the primary study endpoints.

Anti- and pro-fibrillatory effects of pulmonary vein isolation gaps in human atrial fibrillation digital twins

Although pulmonary vein isolation (PVI) gaps and extrapulmonary vein triggers contribute to recurrence after atrial fibrillation (AF) ablation, their precise mechanisms remain unproven. Our study assessed the impact of PVI gaps on rhythm outcomes using a human AF digital twin. We included 50 patients (76.0% with persistent AF) who underwent catheter ablation with a realistic AF digital twin by integrating computed tomography and electroanatomical mapping. We evaluated the final rhythm status, including AF and atrial tachycardia (AT), across 600 AF episodes, considering factors including PVI level, PVI gap number, and pacing locations. Our findings revealed that antral PVI had a significantly lower ratio of AF at the final rhythm (28% vs. 56%, p = 0.002) than ostial PVI. Increasing PVI gap numbers correlated with an increased ratio of AF at the final rhythm (p < 0.001). Extra-PV induction yielded a higher ratio of AF at the final rhythm than internal PV induction (77.5% vs. 59.0%, p < 0.001). In conclusion, our human AF digital twin model helped assess AF maintenance mechanisms. Clinical trial registration: https://www.clinicaltrials.gov ; Unique identifier: NCT02138695.

Comparative Safety of Pulsed Field Ablation and Cryoballoon Ablation Technologies for Pulmonary Vein Isolation in Patients with Paroxysmal Atrial Fibrillation: A Critical Literature Review and Indirect Treatment Comparison

INTRODUCTION

Cryoballoon ablation (CBA) is a standard catheter ablation technology with demonstrated clinical effectiveness for the treatment of paroxysmal atrial fibrillation (PAF); however, it can be associated with major adverse events, including phrenic nerve paralysis. Pulsed field ablation (PFA) is a novel, minimally thermal technology with comparable effectiveness and low safety risk. This study aimed to compare the safety profiles of PFA and CBA through critical analyses of the literature and indirect treatment comparisons.

METHODS

Studies were identified by searching the MEDLINE database and the Clinicaltrials.gov registry. Registered clinical trials and/or Food and Drug Administration Investigation Device Exemption (FDA IDE) studies evaluating PFA or CBA in adult patients with drug-refractory PAF between January 2008 and March 2023 were selected. Comparative safety between PFA and CBA was assessed for major and prespecified adverse events. Indirect comparisons were conducted using the proportion of patients experiencing adverse events and confirmed with single-arm meta-analyses and sensitivity analyses.

RESULTS

Data were extracted from three PFA publications including a total of 497 patients and six CBA studies including a total of 1113 patients. The analysis revealed that PFA was associated with significantly lower risk of major adverse events {risk difference - 4.3% [95% confidence interval (CI) - 5.8, - 2.8]; risk ratio 0.16 [95% CI 0.07, 0.45]} and prespecified adverse events [risk difference - 2.5% (95% CI - 4.4, - 0.5); risk ratio 0.53 (95% CI 0.31, 0.96)]. Meta-analyses confirmed the lower rate of major adverse events for PFA [0.4% (95% CI 0.0, 1.3)] vs. CBA [5.6% (95% CI 2.6, 8.6)] and prespecified adverse events for PFA [2.7% (95% CI 1.2, 4.1)] vs. CBA [5.8% (95% CI 2.7, 9.0)]. Sensitivity analyses exploring heterogeneity across studies confirmed robustness of the main analyses.

CONCLUSION

The findings of this study show that PFA has a more favorable safety profile than CBA, with significantly lower risks of major and prespecified adverse events. These indirect comparisons help contextualize the safety of PFA compared to CBA for the treatment of drug-refractory PAF in the absence of head-to-head studies.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Long-Term Durability of High- and Very High-Power Short-Duration PVI by Invasive Remapping: The HPSD Remap Study

BACKGROUND

High-power short-duration ablation has shown impressive efficacy and safety for pulmonary vein isolation (PVI); however, initial efficacy results with very high power short-duration ablation were discouraging. This study compared the long-term durability of PVI performed with a 90- versus 50-W power setting.

METHODS

Patients were randomized 1:1 to undergo PVI with the QDOT catheter using a power setting of 90 or 50 W. Three months after the index procedure, patients underwent a repeat electrophysiology study to identify pulmonary vein reconnections. Patients were followed for 12 months to detect AF recurrences.

RESULTS

We included 46 patients (mean age, 64 years; women, 48%). Procedure (76 versus 84 minutes; P =0.02), left atrial dwell (63 versus 71 minutes; P =0.01), and radiofrequency (303 versus 1040 seconds; P <0.0001) times were shorter with 90- versus 50-W procedures, while the number of radiofrequency applications was higher with 90 versus 50 W (77 versus 67; P =0.01). There was no difference in first-pass isolation (83% versus 82%; P =1.0) or acute reconnection (4% versus 14%; P =0.3) rates between 90 and 50 W. Forty patients underwent a repeat electrophysiology study. Durable PVI on a per PV basis was present in 72/78 (92%) versus 68/77 (88%) PVs in the 90- and 50-W energy setting groups, respectively; effect size: 72/78-68/77=0.040, lower 95% CI=-0.051 (noninferiority limit=-0.1, ie, noninferiority is met). No complications occurred. There was no difference in 12-month atrial fibrillation-free survival between the 90- and 50-W groups (P =0.2).

CONCLUSIONS

Similarly high rates of durable PVI and arrhythmia-free survival were achieved with 90 and 50 W. Procedure, left atrial dwell, and radiofrequency times were shorter with 90 W compared with 50 W. The sample size is too small to conclude the safety and long-term efficacy of the high and very high-power short-duration PVI; further studies are needed to address this topic.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT05459831.

Cryoballoon ablation of non-PV triggers in persistent atrial fibrillation

Cryoballoon-based catheter ablation has emerged as an efficacious and safe therapeutic intervention for patients with paroxysmal atrial fibrillation (PAF). PAF is primarily associated with the triggers in the pulmonary vein (PV). However, persistent atrial fibrillation (PeAF) is a complex condition that involves changes in the atrial substrate and the presence of non-PV triggers. Therefore, a comprehensive treatment approach is necessary for patients with PeAF. Utilizing a 3D electroanatomical map, the radiofrequency-based ablation technique adeptly identifies and targets the atrial substrate and non-PV triggers. On the other hand, the cryoballoon-based AF ablation was initially designed for PV isolation. However, its single-shot feature makes it a great choice for electrophysiologists looking to address non-PV triggers. It is possible to target the left atrial appendage (LAA), superior vena cava (SVC), left atrial roof, and posterior wall using the apparatus's unique configuration and ablation abilities. This review focuses on the increasing literature regarding cryoballoon-based methods for non-PV trigger ablation. Specifically, it delves into the technical procedures used to isolate the LAA, SVC, and ablate the left atrial roof and posterior wall.

Occlusion and catheter ablation using a large-size cryoballoon for various pulmonary veins: a case series

Background

It is established that pulmonary vein isolation using the POLARx™ (Boston Scientific, Marlborough, MA, USA) cryoballoon is a rapid, safe, and effective approach. The new POLARx™ FIT (Boston Scientific), which is expandable from 28 to 31 mm in diameter, is currently available. However, there is limited evidence available regarding the treatment of atrial fibrillation in this setting. In this article, we report a case series of cryoballoon ablation in patients with atrial fibrillation using POLARx™ FIT.

Case summary

This case series describes a comparison of obstruction in three patients with pulmonary veins of different shapes and diameters undergoing cryoballoon ablation and pulmonary vein isolation with a 31 mm diameter balloon.

Discussion

Cryoballoon ablation using the 31 mm mode of POLARx™ FIT has the potential to provide safe and stable pulmonary vein isolation with good occlusion for a variety of pulmonary vein geometries. In this case series, the 31 mm mode of the POLARx™ FIT resulted in better pulmonary vein occlusion than the 28 mm mode in patients with large left atria and large pulmonary veins, including the left common pulmonary vein. This approach may be considered a first-line therapy option of cryoballoon ablation in patients with atrial fibrillation.

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.

An evaluation of the clinical efficacy of the application of 28mm cryoballoon for linear ablation of left atrial apex combined with enlarged pulmonary vein vestibule ablation for persistent atrial fibrillation

OBJECTIVE

to retrospectively investigate the efficacy and safety of the application of 28 mm cryoballoon for pulmonary vein electrical isolation (PVI) combined with top left atrial linear ablation and pulmonary vein vestibular expansion ablation for persistent atrial fibrillation.

METHODS

From July 2016 to December 2020, 413 patients diagnosed with persistent atrial fibrillation were evaluated, including 230 (55.7%) in the PVI group (PVI only) and 183 (44.3%) in the PVIPLUS group (PVI plus ablation of the left atrial apex and pulmonary vein vestibule). The safety and efficacy of the two groups were retrospectively analyzed.

RESULTS

The AF/AT/AFL-free survival rates at 6, 12, 18, 24 and 30 months after procedure was 86.6%, 72.6%, 70.0%, 61.1% and 56.3% in the PVI group and 94.5%, 87.0%, 84.1%, 75.0% and 67.9% in the PVIPLUS group, respectively. At 30 months after procedure, the AF/AT/AFL-free survival rate was significantly higher in the PVIPLUS group than in the PVI group (P = 0.036; HR:0.63; 95% CI:0.42 to 0.95).

CONCLUSION

The application of 28-mm cryoballoon for pulmonary vein electrical isolation combined with linear ablation of the left atrial apex and expanded ablation of the pulmonary vein vestibule improves the outcome of persistent atrial fibrillation.

Differential gap location after radiofrequency versus cryoballoon pulmonary vein isolation: Insights from a randomized trial with protocol-mandated repeat procedure

INTRODUCTION

Reconnections to pulmonary vein (PV) triggers of atrial fibrillation (AF) are the primary cause of AF recurrence after PV isolation (PVI) with radiofrequency (RF) or cryoballoon catheter ablation (CRYO), but method-specific contributions to PV reconduction pattern and conductive gap location are incompletely understood.

METHODS

The objective of this radiofrequency versus cryoballoon catheter ablation for paroxysmal atrial fibrillation substudy was to determine procedure-specific patterns of PV reconduction in a randomized population with protocol-mandated repeat procedures, irrespective of AF recurrence. Each PV was assessed in turn and PV reconnection sites were identified by high-density electroanatomical mapping and locating the earliest activation site. Gap locations were verified by PV re-isolation.

RESULTS

In 98 patients, 81% versus 76% previously isolated PVs remained isolated after CRYO versus RF (risk ratio [RR]: 1.06; 95% confidence interval [CI]: 0.96-1.18; p = .28). There were no significant differences for any PV: left superior PV: 90% versus 80%; left inferior PV: 80% versus 78%; right superior PV: 81% versus 80%, and right inferior PV: 76% versus 73%. For each reconnected PV, 34% of ipsilateral PVs were also reconnected after CRYO compared with 64% after RF (RR: 0.54; 95% CI: 0.32-0.90; p = .01). After RF, gaps were clustered by the carina and adjacent segments, whereas they were more heterogeneously distributed after CRYO.

CONCLUSION

Although RF and CRYO produce similar proportions of durably isolated PVs, gap locations appear to develop in procedure-specific patterns. After RF, ipsilateral PV reconduction is more frequent and gap sites cluster by the carina, suggesting that this region should be selectively ablated for more durable PVI.

Recurrences of Atrial Fibrillation Despite Durable Pulmonary Vein Isolation: The PARTY-PVI Study

BACKGROUND

Recurrences of atrial fibrillation (AF) after pulmonary vein isolation (PVI) are mainly due to pulmonary vein reconnection. However, a growing number of patients have AF recurrences despite durable PVI. The optimal ablative strategy for these patients is unknown. We analyzed the impact of current ablation strategies in a large multicenter study.

METHODS

Patients undergoing a redo ablation for AF and presenting durable PVI were included. The freedom from atrial arrhythmia after pulmonary vein-based, linear-based, electrogram-based, and trigger-based ablation strategies were compared.

RESULTS

Between 2010 and 2020, 367 patients (67% men, 63±10 years, 44% paroxysmal) underwent a redo ablation for AF recurrences despite durable PVI at 39 centers. After durable PVI was confirmed, linear-based ablation was performed in 219 (60%) patients, electrogram-based ablation in 168 (45%) patients, trigger-based ablation in 101 (27%) patients, and pulmonary vein-based ablation in 56 (15%) patients. Seven patients (2%) did not undergo any additional ablation during the redo procedure. After 22±19 months of follow-up, 122 (33%) and 159 (43%) patients had a recurrence of atrial arrhythmia at 12 and 24 months, respectively. No significant difference in arrhythmia-free survival was observed between the different ablation strategies. Left atrial dilatation was the only independent factor associated with arrhythmia-free survival (HR, 1.59 [95% CI, 1.13-2.23]; P=0.006).

CONCLUSIONS

In patients with recurrent AF despite durable PVI, no ablation strategy used alone or in combination during the redo procedure appears to be superior in improving arrhythmia-free survival. Left atrial size is a significant predictor of ablation outcome in this population.

Twelve-month efficacy of second-generation cryoballoon ablation for atrial fibrillation performed at community hospitals: results of the German register on cryoballoon ablation in local hospitals (regional)

BACKGROUND

The 12-month follow-up (F/U) efficacy of CBA PVI performed at community hospitals for treatment of symptomatic paroxysmal and persistent atrial fibrillation (AF) is unknown. This study determined the 12-month efficacy of pulmonary vein isolation (PVI) using cryoballoon ablation (CBA) performed at community hospitals with limited annual case numbers.

METHODS

This registry study included 983 consecutive patients (pts) from 19 hospitals, each with an annual procedural volume of < 100 PVI procedures/year. Pts underwent CBA PVI for paroxysmal AF (n = 520), persistent AF (n = 423), or redo PVI (n = 40). The primary endpoint was frequency of documented recurrent AF, the occurrence of atrial flutter or tachycardia following a 90-day period after the index ablation and up to 12 months. The frequency of repeat ablation was determined.

RESULTS

Isolation of all PVs was documented in 98% of pts at the end of the procedure. Twelve-month F/U data could be obtained in 916 pts. A 24-h ECG registration was performed in 641 pts (70.0%); in 107 pts (16.7%) of them, recurrent AF was documented. The primary endpoint was met in 193 F/U pts (21.1%). It occurred in 80/486 F/U pts with paroxysmal AF (16.4%), and in 107/390 F/U pts with persistent AF (27.4%). Redo PVI was performed in 71 pts (7.8%), and atrial flutter ablation was performed in 12 pts (1.4%).

CONCLUSIONS

CBA PVI for paroxysmal or persistent AF can be performed at community hospitals with adequate rates of 12-month symptom freedom and arrhythmia recurrence. The study was registered at the German register of clinical studies (DRKS00016504).

Cryoballoon Pulmonary Vein Isolation as First-Line Treatment for Typical Atrial Flutter

OBJECTIVE

We aimed to compare cryoballoon pulmonary vein isolation (PVI) with standard radiofrequency cavotricuspid isthmus (CTI) ablation as first-line treatment for typical atrial flutter (AFL).

METHODS

Cryoballoon Pulmonary Vein Isolation as First-Line Treatment for Typical Atrial Flutter was an international, multicentre, open with blinded assessment trial. Patients with CTI-dependent AFL and no documented atrial fibrillation (AF) were randomised to either cryoballoon PVI alone or radiofrequency CTI ablation. Primary efficacy outcome was time to first recurrence of sustained (>30 s) symptomatic atrial arrhythmia (AF/AFL/atrial tachycardia) at 12 months as assessed by continuous monitoring with an implantable loop recorder. Primary safety outcome was a composite of death, stroke, tamponade requiring drainage, atrio-oesophageal fistula, pacemaker implantation, serious vascular complications or persistent phrenic nerve palsy.

RESULTS

Trial recruitment was halted at 113 of the target 130 patients because of the SARS-CoV-2 pandemic (PVI, n=59; CTI ablation, n=54). Median age was 66 (IQR 61-71) years, with 98 (86.7%) men. At 12 months, the primary outcome occurred in 11 (18.6%) patients in the PVI group and 9 (16.7%) patients in the CTI group. There was no significant difference in the primary efficacy outcome between the groups (HR 1.11, 95% CI 0.46 to 2.67). AFL recurred in six (10.2%) patients in the PVI arm and one (1.9%) patient in the CTI arm (p=0.116). Time to occurrence of AF of ≥2 min was significantly reduced with cryoballoon PVI (HR 0.46, 95% CI 0.25 to 0.85). The composite safety outcome occurred in four patients in the PVI arm and three patients in the CTI arm (p=1.000).

CONCLUSION

Cryoballoon PVI as first-line treatment for AFL is equally effective compared with standard CTI ablation for preventing recurrence of atrial arrhythmia and better at preventing new-onset AF.

TRIAL REGISTRATION NUMBER

NCT03401099.

Clinical utility of the "balloon lever technique" in the right inferior pulmonary vein cryoballoon ablation

Background

The acute success rate of pulmonary vein isolation (PVI) with cryoballoon (CB) is reported to be lower in the right inferior pulmonary vein (RIPV). This study aimed to investigate the utility of the "balloon lever technique (BLT)" for RIPV CB ablation.

Methods

We retrospectively studied consecutive patients who underwent CB-PVI for atrial fibrillation between February 21, 2020 and June 3, 2022. RIPV cryoablation was performed according to a specific protocol. The patients underwent RIPV cryoablation using the conventional method. If the method was found ineffective, BLT cryoablation was performed. The acute success rate of RIPV CB ablation was examined. We also investigated the RIPV isolation rate and procedural parameters during conventional and BLT cryoablation.

Results

Ninety-three patients were included in the analysis. RIPV isolation was achieved in 89.2% (83/93) of the patients using conventional method and subsequent BLT cryoablation. Meanwhile, 68 patients underwent BLT cryoablation because the conventional method was ineffective. RIPV was isolated with BLT in 85.3% (58/68) of patients. Additionally, BLT was found to be superior to conventional cryoablation in terms of nadir balloon temperature, freezing time, and thawing time to a specific temperature in patients who underwent both conventional and BLT cryoablations.

Conclusions

BLT is useful in RIPV cryoablation when the conventional method is ineffective. BLT cryoablation may be helpful, mainly because of the BLT-mediated contact of the balloon with the bottom of the RIPV, which leads to optimal RIPV occlusion.

Best Practice Guide for Cryoballoon Ablation in Atrial Fibrillation: The Compilation Experience of More than 1000 Procedures

Nowadays, the cryoballoon (CB) constitutes an established alternative to radio frequency (RF) ablation for pulmonary vein isolation (PVI), which offers the possibility to isolate the PVs with a single application. Since the introduction of the second-generation CB, we prospectively collected our data to optimize the procedure on >1000 consecutive patients who underwent CB PVI performed in our center. It is expected that subsequent guidelines will suggest first-line PVI through CB in patients with paroxysmal AF with a class I indication. Indeed, in the long-term follow-up (36 months) of the EARLY-AF trial, CB had a lower incidence of persistent atrial fibrillation episodes compared to the anti-arrhythmic drugs group. We now review the current best practices in an effort to drive consistent outcomes and minimize complications. PV isolation through CB is the most studied single-shot technique for atrial fibrillation ablation, having shown the potential to alter the natural history of the arrhythmia. Several procedural tips and tricks can improve procedural flow and effectiveness. In the present article we provided not only technical details but measurable biophysical parameters that can reliably guide the operator into achieving the best outcome for his patients.

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.

WITHDRAWN: Prevalence and factors associated with smoking in a nationally representative sample of Greek adults: The Hellenic National Nutrition and Health Survey (HNNHS)

The Publisher regrets that this article is an accidental duplication of an article that has already been published, https://doi.org/10.1016/j.hjc.2022.05.005. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal

Frozen, Gone in 60 Seconds!

The field of electrophysiology has seen the development of a novel ultralow temperature cryoablation (ULTC) system. The data presented in this manuscript shows that the ULTC system is feasible, safe, and effective in acute PVI under sedation and by using angiography only This article is protected by copyright. All rights reserved.

Impact of a time-to-effect guided ablation protocol in cryoballoon ablation on durability of pulmonary vein isolation

BACKGROUND

Cryoballoon (CB) based pulmonary vein isolation (PVI) has proven to be as effective as radiofrequency (RF) based ablation. Different ablation protocols took the individual time-to-isolation (TTI) into account aiming at shorter but equally or even more effective freeze-cycles. The current study sought to assess the impact of the TTI on PVI durability in patients undergoing a repeat procedure for recurrence of atrial tachyarrhythmia (ATA).

METHODS AND RESULTS

In 205 patients with ATA recurrence after previous CB-based PVI a total of 806 PVs were identified. One hundred-twenty-six out of 806 PVs (16%) were previously treated with a TTI guided ablation (protocol #1; TTI+120 sec.), in 92/806 (11%) PVs TTI was only monitored (m) but fixed freeze-cycles were applied (protocol #2; mTTI) and in 588/806 (73%) a fixed freeze-cycle was applied without TTI-monitoring. There was no difference in the PV-reconduction rate between the groups (p=0.23). The right inferior pulmonary vein (RIPV) showed overall significantly higher reconduction rates compared to the other PVs (RIPV - left inferior PV (LIPV) p<0.003, -left superior PV (LSPV) p<0.001, - right superior PV RSPV p<0.013). Twenty-one patients (10%) were demonstrated to have only electrical reconduction of the RIPV, while all other PVs were still electrically isolated.

CONCLUSIONS

TTI based CB ablation did not show significant differences regarding PV-reconduction rates compared to the other protocols. This article is protected by copyright. All rights reserved.

Pulsed-field ablation combined with ultrahigh-density mapping in patients undergoing catheter ablation for atrial fibrillation: Practical and electrophysiological considerations

BACKGROUND

Pulsed-field ablation (PFA) yields a novel ablation technology for atrial fibrillation (AF). PFA lesions promise to be highly durable, however clinical data on lesion characteristics are still limited.

OBJECTIVE

This study sought to investigate PFA lesion creation with ultrahigh-density (UHDx) mapping.

METHODS

Consecutive AF patients underwent PFA-based pulmonary vein isolation (PVI) using a multispline catheter (Farwave, Farapulse Inc.). Additional ablation, including left atrial posterior wall isolation (LAPWI) and mitral isthmus ablation (MI) were performed in a subset of persistent AF patients. The extent of PFA-lesions and decrease of LA-voltage were assessed with pre- and post PFA UHDx-mapping (Orion™ catheter and Rhythmia™ 3D-mapping system, Boston Scientific).

RESULTS

In 20 patients, acute PVI was achieved in 80/80 PVs, LAPW isolation in 9/9 patients, MI ablation in 2/2 (procedure time: 123 ± 21.6 min, fluoroscopy time: 19.2 ± 5.5 min). UHDx-mapping subsequent to PVI revealed early PV-reconnection in five case (5/80, 6.25%). Gaps were located at the anterior-superior PV ostia and were successfully targeted with additional PFA. Repeat UHDx mapping after PFA revealed a significant decrease of voltage along the PV ostia (1.67 ± 1.36 mV vs. 0.053 ± 0.038 mV, p < .0001) with almost no complex electrogram-fractionation at the lesion border zones. PFA-catheter visualization within the mapping system was feasible in 17/19 (84.9%) patients and adequate in 92.9% of ablation sites.

CONCLUSION

For the first time illustrated by UHDx mapping, PFA creates wide antral circumferential lesions and homogenous LAPW isolation with depression of tissue voltage to a minimum. Although with a low incidence, early PV reconnection can still occur also in the setting of PFA.

Phrenic Nerve Injury During Cryoballoon-Based Pulmonary Vein Isolation: Results of the Worldwide YETI Registry

BACKGROUND

Cryoballoon-based pulmonary vein isolation (PVI) has emerged as an effective treatment for atrial fibrillation. The most frequent complication during cryoballoon-based PVI is phrenic nerve injury (PNI). However, data on PNI are scarce.

METHODS

The YETI registry is a retrospective, multicenter, and multinational registry evaluating the incidence, characteristics, prognostic factors for PNI recovery and follow-up data of patients with PNI during cryoballoon-based PVI. Experienced electrophysiological centers were invited to participate. All patients with PNI during CB2 or third (CB3) and fourth-generation cryoballoon (CB4)-based PVI were eligible.

RESULTS

A total of 17 356 patients underwent cryoballoon-based PVI in 33 centers from 10 countries. A total of 731 (4.2%) patients experienced PNI. The mean time to PNI was 127.7±50.4 seconds, and the mean temperature at the time of PNI was -49±8°C. At the end of the procedure, PNI recovered in 394/731 patients (53.9%). Recovery of PNI at 12 months of follow-up was found in 97.0% of patients (682/703, with 28 patients lost to follow-up). A total of 16/703 (2.3%) reported symptomatic PNI. Only 0.06% of the overall population showed symptomatic and permanent PNI. Prognostic factors improving PNI recovery are immediate stop at PNI by double-stop technique and utilization of a bonus-freeze protocol. Age, cryoballoon temperature at PNI, and compound motor action potential amplitude loss >30% were identified as factors decreasing PNI recovery. Based on these parameters, a score was calculated. The YETI score has a numerical value that will directly represent the probability of a specific patient of recovering from PNI within 12 months.

CONCLUSIONS

The incidence of PNI during cryoballoon-based PVI was 4.2%. Overall 97% of PNI recovered within 12 months. Symptomatic and permanent PNI is exceedingly rare in patients after cryoballoon-based PVI. The YETI score estimates the prognosis after iatrogenic cryoballoon-derived PNI. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03645577. Graphic Abstract: A graphic abstract is available for this article.

Safety and Efficacy of Cryoballoon Ablation of Atrial Fibrillation in relation to the Patients' Age: Results from a Large Real-World Multicenter Observational Project

BACKGROUND

The real-world efficacy and safety of atrial fibrillation (AF) ablation in particularly young and elderly patients are still under debate. The aim of the analysis was to investigate the effect of age on the efficacy and safety of cryoballoon ablation (CBA).

METHODS

2,534 patients underwent pulmonary vein isolation (PVI) by way of CBA for paroxysmal or persistent drug-resistant and symptomatic AF. The population was divided into age quartiles for evaluation, including (1) <53 years, (2) ≥53 and <61 years, (3) ≥61 and <67 years, and (4) ≥67 years. Furthermore, outcomes were analyzed in patients <41 years, ≥41 and ≤74, and >74 years old. Procedural data and complications were collected, and atrial fibrillation recurrences were evaluated during follow-up.

RESULTS

Procedural-related complications (4.1%) were similar in the four subgroups according to age. At the 12-month follow-up, freedom from AF recurrence was 79.2%, 77.4%, 76.8%, and 75.2% (p=0.21), respectively (with increasing age). At 24-month follow-up, similar incidences of AF recurrence were observed in the four subgroups. When the sample was arbitrarily divided into the three age groups, a higher rate of recurrence was observed in older patients with regard to long-term follow-up (freedom from AF recurrence was 71.8% and 40.9%, respectively, at 12 and 24-month follow-up). In the univariate and multivariate analysis, age did not result in a significant predictor of AF recurrence during follow-up; however, a trend toward higher AF recurrences rates in patients ≥67 years was observed.

CONCLUSION

The data demonstrated a high degree of safety during CBA across all patient ages. Procedural performance and complications were similar between different ages; AF recurrences seem to be more frequent in patients over 74 years.

[Practical guide for safe and efficient cryoballoon ablation for atrial fibrillation : Practical procedure, tips and tricks]

In the current guidelines on treatment of atrial fibrillation, cryoballoon-based catheter ablation of atrial fibrillation is recommended in addition to radiofrequency ablation and has become established as a standard procedure in the clinical routine of many centers for index pulmonary vein isolation. A safe, simplified and often durable pulmonary vein isolation can be achieved by a systematic approach. This review article provides a practical guide for all steps of cryoballoon-based pulmonary vein isolation, including preprocedural preparation and postinterventional follow-up. Both cryoballoon systems currently available on the market are considered.

Cardiac computed tomography angiography-derived analysis of left atrial appendage morphology and left atrial dimensions for the prediction of atrial fibrillation recurrence after pulmonary vein isolation

Background

Left atrial appendage (LAA) is a potential source of atrial fibrillation (AF) triggers.

Hypothesis

LAA morphology and dimensions are associated with AF recurrence after pulmonary vein isolation (PVI).

Methods

From cardiac computed tomography angiography (CCTA), left atrial (LA), pulmonary vein (PV), and LAA anatomy were assessed in cryoballoon ablation (CBA) patients.

Results

Among 1103 patients undergoing second‐generation CBA, 725 (65.7%) received CCTA with 473 (42.9%) qualifying for detailed LAA analysis (66.3 ± 9.5 years). Symptomatic AF reoccurred in 166 (35.1%) patients during a median follow‐up of 19 months. Independent predictors of recurrence were LA volume, female sex, and mitral regurgitation ≥°II. LAA volume and AF‐type were dependent predictors of recurrence due to their strong correlations with LA volume. LA volumes ≥122.7 ml (sensitivity 0.53, specificity 0.69, area under the curve [AUC] 0.63) and LAA volumes ≥11.25 ml (sensitivity 0.39, specificity 0.79, AUC 0.59) were associated with recurrence. LA volume was significantly smaller in females. LAA volumes showed no sex‐specific difference. LAA morphology, classified as windsock (51.4%), chicken‐wing (20.7%), cactus (12.5%), and cauliflower‐type (15.2%), did not predict successful PVI (log‐rank; p = 0.596).

Conclusions

LAA volume was strongly correlated to LA volume and was a dependent predictor of recurrence after CBA. Main independent predictors were LA volume, female sex, and mitral regurgitation ≥°II. Gender differences in LA volumes were observed. Individual LAA morphology was not associated with AF recurrence after cryo‐PVI. Our results indicate that preprocedural CCTA might be a useful imaging modality to evaluate ablation strategies for patients with recurrences despite successful PVI.

Contrast-enhanced computed tomography for optimizing the outcomes of pulmonary vein isolation with cryoablation -the role of isolation of PVs including carina

Purpose

Compared with conventional pulmonary vein isolation (PVI) with radiofrequency ablation, PVI with cryoballoon is an easier and shorter procedure without reconnection, particularly in the superior pulmonary vein. However, the durability of the cryoballoon may be reduced due to anatomical factors and the position of the pulmonary vein (PV). Further, inadequate isolation of the carina leads to recurrence of atrial fibrillation (AF). We aimed to determine whether using contrast-enhanced computed tomography (CT) for patient selection improves the early success rate and prevents the recurrence of AF in PVI with cryoballoon.

Methods

We evaluated patients who underwent ablation for paroxysmal atrial fibrillation in our hospital between July 2019 and November 2020. After excluding patients with contraindications for cryoablation, 50 patients were selected through visual inspection of the results of preoperative contrast-enhanced CT. A treatment plan was established, and the clinical course and outcomes were followed up.

Results

Of the 200 PVs of the 50 patients, only 8 PVs (4%) were incompletely isolated with a single cryoablation. Six of the eight PVs were successfully isolated with additional cryoablation. Only 2 patients (4%) underwent additional PVI with radiofrequency ablation. Four patients had AF recurrence within a mean follow-up period of 14.3 ± 5.1 months. The rate of sinus rhythm maintenance was 92%. PV reconnection was observed in 2 patients. None of the patients had postoperative atrial flutter.

Conclusions

Selecting patients for cryoablation according to contrast-enhanced CT findings made the procedure easier to perform, leading to improved early success rates and clinical course.

Rationale and Outcomes of Cryoballoon Ablation of the Left Atrial Posterior Wall in Conjunction with Pulmonary Vein Isolation

There is strong evidence in support of pulmonary vein isolation (PVI) with concomitant left atrial (LA) posterior wall (PW) isolation (PWI) for the treatment of patients with persistent atrial fibrillation (persAF). While this may be achieved using surgical and catheter-based strategies, there is growing interest in performing this approach using the cryoballoon. There are several potential advantages to this strategy. First, lesions created using the current-generation cryoballoons are typically large and durable. Second, cryoballoon ablation offers a simple technique to directly ablate and debulk the LAPW. Moreover, some consider cryoenergy a safer modality specifically with regard to collateral structures (ie, the esophagus). Based on the available data, cryoballoon PVI + PWI is associated with greater intraprocedural AF terminations and reductions in long-term AF recurrence (typically by ~20%), as compared to PVI alone in patients with persAF, but with similar rates of adverse events. As such, PVI + PWI has emerged as a significant predictor of freedom from recurrent AF (odds ratio: 3.67, 95% confidence interval: 1.44-9.34; p = 0.006) as well as all atrial arrhythmias (hazard ratio: 2.04, 95% confidence interval: 1.15-3.61; p = 0.015). Adjunct radiofrequency ablation to complete PWI is required in at least one-third of the patients, and this need is highly predicted by the LA size (significantly increased with an LA diameter > 48 mm). LAPW reconnection also seems to be associated with LA dimension, particularly an LA diameter greater than 48 mm (negative predictive value: 89.7%). Nevertheless, based on the analysis of patients who underwent repeat electrophysiology study for arrhythmia recurrences, cryoballoon PVI + PWI yields acceptable long-term durability (> 80%).

Safety and acute efficacy of cryoballoon ablation for atrial fibrillation at community hospitals

AIMS

Pulmonary vein isolation (PVI) using cryoballoon ablation (CBA) is an established procedure for treating symptomatic paroxysmal and persistent atrial fibrillation (AF). The safety and efficacy of PVI performed at community hospitals are unknown. We aimed to determine the safety and acute efficacy of PVI using CBA performed at community hospitals with limited annual case numbers.

METHODS AND RESULTS

This registry study included 1004 consecutive patients who had PVI performed for symptomatic paroxysmal (n = 563) or persistent AF (n = 441) from January 2019 to September 2020 at 20 hospitals. Each hospital performed fewer than 100 CBA-PVI procedures/year according to local standards. Procedural data, efficacy, and complication rates were determined. The mean number of CBA procedures performed/year at each centre was 59 ± 25. The average procedure time was 90.1 ± 31.6 min and the average fluoroscopy time was 19.2 ± 11.4 min. Isolation of all pulmonary veins was documented in 97.9% of patients. The most frequent reason for not achieving complete isolation was development of phrenic nerve palsy. No hospital deaths were observed. Two patients (0.2%) suffered a clinical stroke. Pericardial effusion occurred in six patients (0.6%), two of whom (0.2%) required pericardial drainage. Vascular complications occurred in 24 patients (2.4%), two of whom (0.2%) required vascular surgery. Phrenic nerve palsy occurred in 48 patients (4.8%) and persisted up to hospital discharge in six patients (0.6%).

CONCLUSION

Pulmonary vein isolation procedures for paroxysmal or persistent AF using CBA can be performed at community hospitals with high acute efficacy and low complication rates.

Catheter ablation as first-line treatment for paroxysmal atrial fibrillation: a systematic review and meta-analysis

OBJECTIVE

To assess the efficacy and safety of catheter ablation (CA) compared with antiarrhythmic drugs (AADs) as first-line treatment for symptomatic paroxysmal atrial fibrillation (AF).

METHODS

Systematic review and meta-analysis of randomised controlled trials identified using MEDLINE, Cochrane Library and Embase published between 01/01/2000 and 19/03/2021. The primary efficacy endpoint was the first documented recurrence of atrial arrhythmias following the blanking period. The primary safety endpoint was a composite of all serious adverse events (SAEs).

RESULTS

From 441 records, 6 studies met the inclusion criteria. 609 patients received CA, while 603 received AAD therapy. 212/609 patients in the CA group had a recurrence of atrial arrhythmias as compared with 318/603 in the AADs group resulting in a 36% relative risk reduction (risk ratio: 0.64, 95% CI 0.51 to 0.80, p<0.01). The risk of all SAEs was not statistically different between CA and AAD (0.87, 0.58 to 1.30, p=0.49); 107/609 SAE in the CA group vs 126/603 in the AAD group. Both recurrence of symptomatic atrial arrhythmias (109/505 vs 186/504) and healthcare utilisation (126/397 vs 185/394) were significantly lower in the CA group (0.53, 0.35 to 0.79 and 0.65, 0.48 to 0.89, respectively). There was a 79% reduction in the crossover rate during follow-up among patients randomised to CA compared with AAD (0.21, 0.13 to 0.32, p<0.01).

CONCLUSIONS

First-line treatment with CA is superior to AAD therapy in patients with symptomatic paroxysmal AF, as it significantly reduces the recurrence of any atrial arrhythmias and symptomatic atrial arrhythmias, and healthcare resource utilisation with comparable safety profile.

Durability of a right superior pulmonary vein isolation after an inevitably interrupted single short freeze during cryoballoon ablation

BACKGROUND

In cryoballoon ablation, applications for right superior pulmonary veins (RSPVs) inevitably need to be interrupted for some safety reasons. We retrospectively investigated the RSPV isolation durability after single interrupted short freezes.

METHODS

Data from 30 patients who underwent repeat procedures 8.2 (4.1-13.8) months after an inevitably interrupted single short freeze (<180 s) for RSPVs during the index cryoballoon procedures were analyzed. It was interrupted by active deflation due to phrenic nerve injury (PNI) (Group 1: n = 14) or passive deflation due to a balloon temperature of -60°C (Group 2: n = 16).

RESULTS

The freezing time was 145 (107-166) and 142 (127-160) s and nadir balloon temperature -50.7 ± 3.6 and -60°C in Groups 1 and 2, respectively. Pulmonary vein isolation was achieved after interrupted freezing in all except in one patient requiring touch-up ablation in Group 1. All PNI was asymptomatic and recovered during the follow-up. Eight/13 (61.5%) and 16/16 (100%) RSPVs were durable during the second procedure in Groups 1 and 2. In Group 1, the freezing time was significantly longer in durable than reconnected RSPVs (p = .032), and the optimal cutoff point for the freezing duration to predict the durability was 94.0 s (sensitivity 100%, specificity 60.0%). When the freezing time was ≥120 s, 80% of the RSPVs were durable. However, when the freezing time was ≤68 s, all RSPVs were reconnected.

CONCLUSIONS

The feasibility of second cryoapplications for RSPVs should be discussed considering the freezing time of the interrupted initial applications in Group 1, however, it was not necessary in Group 2.

Benefit of ultra-high-density mapping-guided radiofrequency reablation in pulmonary vein isolation non-responders after initial cryoballoon procedure

AIMS

Symptomatic atrial arrhythmias despite complete pulmonary vein isolation (PVI) are common. The purpose was to evaluate ultra-high-density multi-electrode electroanatomical mapping-guided radiofrequency ablation (RFA) in PVI non-responders.

METHODS AND RESULTS

Ultra-high-density multi-electrode electroanatomical mapping-guided RFA in consecutive symptomatic atrial fibrillation (AF) patients after initial cryoballoon PVI was performed. Patients were included if all pulmonary veins (PVs) were still isolated. Radiofrequency targets were atrial tachycardia (AT), extra-PV trigger, and/or substrate. Procedural results and outcome were evaluated. Of 95 patients, 67 (70.5%) with complete PVI were included (70 years, CHA2DS2Vasc 2.9, left atrium 45 mm, persistent AF 45%, AT 45%). The median time to reablation was 26 months. One hundred and seven maps (1.6/patient) and 11.890 ± 9.018 electrograms were acquired in 33 ± 12 min. Twenty-eight percent of the left atrial (LA) wall showed pathological voltage signals, predominantly at the anterior (37%) and septal wall (26%). Atrial tachycardia (49 left, 4 right) were ablated in 35 patients (52%), extra-PV trigger in two patients (3%). One atrioventricular nodal re-entry tachycardia and seven right atrial isthmus ablation (10%) were performed. In 32 patients (48%), no AT was present and substrate-based ablation was performed. Mean LA area ablated was 7 ± 6 cm2 (7%). No major complication occurred. The mean follow-up time was 772 ± 317 days. Freedom from atrial arrhythmia recurrence off antiarrhythmic drugs was 49% at 12 months.

CONCLUSION

Pulmonary vein isolation non-responders are older, mainly suffering from complex atrial arrhythmias. Left atrial substrate is predominantly located at the anterior and septal wall. Ultra-high-density multi-electrode electroanatomical mapping-guided RFA is safe and effective. At 1 year, 5 out of 10 patients were in stable sinus rhythm off antiarrhythmic drugs.

The long-term effect of thermal-guided second-generation cryoablation in paroxysmal and persistent atrial fibrillation

BACKGROUND

Second-generation cryoballoon ablation is safe and effective in patients with paroxysmal (PAF) and persistent atrial fibrillation (AF).

OBJECTIVE

This study aimed to assess the long-term clinical outcomes and freedom from AF in patients undergoing thermal-guided cryoablation without the use of an electrical mapping catheter.

METHODS

All patients who had undergone thermal-guided second-generation cryoablation without electrical mapping between January 2015 and April 2018 at Eastbourne District General Hospital were retrospectively analysed. Success was defined as freedom from atrial arrhythmia lasting >30 s during the follow up period.

RESULTS

The study included 234 patients with a mean age of 65.3 ± 10.6 years. There were 134 (57.0%) and 100 (42.7%) patients who had PAF and persistent AF respectively. Arrhythmia recurrence occurred in 38 of 134 (28.4%) PAF and 42 of 100 (42.0%) persistent AF patients after mean follow up of 40 ± 9.2 months. The patients with PAF had a significantly greater freedom from arrhythmia than patients with persistent AF (p = .040). The mean procedure time was 55.5 ± 12.2 min and the mean fluoroscopy time was 10.9 ± 4.8 min 73.5% of patients were discharged on the same day.

CONCLUSION

Thermal-guided cryoablation is feasible, safe and results in freedom from arrhythmia in the majority of paroxysmal and persistent AF patients in the long term. Randomised controlled trials are required to confirm the findings of this study.

Pulsed Field Ablation of Paroxysmal Atrial Fibrillation: 1-Year Outcomes of IMPULSE, PEFCAT, and PEFCAT II

OBJECTIVES

This study sought to determine whether durable pulmonary vein isolation (PVI) using pulsed field ablation (PFA) translates to freedom from atrial fibrillation recurrence without an increase in adverse events.

BACKGROUND

PFA is a nonthermal ablative modality that, in preclinical studies, is able to preferentially ablate myocardial tissue with minimal effect on surrounding tissues. Herein, we present 1-year clinical outcomes of PFA.

METHODS

In 3 multicenter studies (IMPULSE [A Safety and Feasibility Study of the IOWA Approach Endocardial Ablation System to Treat Atrial Fibrillation], PEFCAT [A Safety and Feasibility Study of the FARAPULSE Endocardial Ablation System to Treat Paroxysmal Atrial Fibrillation], and PEFCAT II [Expanded Safety and Feasibility Study of the FARAPULSE Endocardial Multi Ablation System to Treat Paroxysmal Atrial Fibrillation]), paroxysmal atrial fibrillation patients underwent PVI using a basket or flower PFA catheter. Invasive remapping was performed at ∼2 to 3 months, and reconnected PVs were reisolated with PFA or radiofrequency ablation. After a 90-day blanking period, arrhythmia recurrence was assessed over 1-year follow-up.

RESULTS

In 121 patients, acute PVI was achieved in 100% of PVs with PFA alone. PV remapping, performed in 110 patients at 93.0 ± 30.1 days, demonstrated durable PVI in 84.8% of PVs (64.5% of patients), and 96.0% of PVs (84.1% of patients) treated with the optimized biphasic energy PFA waveform. Primary adverse events occurred in 2.5% of patients (2 pericardial effusions or tamponade, 1 hematoma); in addition, there was 1 transient ischemic attack. The 1-year Kaplan-Meier estimates for freedom from any atrial arrhythmia for the entire cohort and for the optimized biphasic energy PFA waveform cohort were 78.5 ± 3.8% and 84.5 ± 5.4%, respectively.

CONCLUSIONS

PVI with a "single-shot" PFA catheter results in excellent PVI durability and acceptable safety with a low 1-year rate of atrial arrhythmia recurrence. These data mitigate concern that the nonthermal ablative mechanism of PFA might mask undiscovered compromises to clinical success. (IMPULSE: A Safety and Feasibility Study of the IOWA Approach Endocardial Ablation System to Treat Atrial Fibrillation, NCT03700385; A Safety and Feasibility Study of the FARAPULSE Endocardial Ablation System to Treat Paroxysmal Atrial Fibrillation, NCT03714178; PEFCAT II Expanded Safety and Feasibility Study of the FARAPULSE Endocardial Multi Ablation System to Treat Paroxysmal Atrial Fibrillation [PEFCAT II], NCT04170608).

Segmental nonocclusive cryoballoon ablation of pulmonary veins and extrapulmonary vein structures: Best practices III

Although cryoballoon ablation of atrial fibrillation (AF) traditionally has been guided by pulmonary vein (PV) occlusion, there is evidence and growing interest in performing segmental, nonocclusive cryoballoon ablation to target not only large/common PVs but extra-PV structures such as the left atrial (LA) roof and posterior wall in conjunction with PV isolation. A number of studies have demonstrated improved clinical efficacy associated with nonocclusive cryoballoon ablation of the LA roof and posterior wall in addition to PV isolation, particularly in patients with persistent AF. Not only can the cryoballoon be used for targeting extra-PV structures through segmental, nonocclusive ablation, but the large size and durability of cryolesions coupled with the enhanced stability afforded through cryoadhesion render the cryoballoon an effective tool for such an approach. This article reviews the rationale and practical approach to segmental, nonocclusive cryoballoon ablation of large/common PV antra and the LA roof and posterior wall.

Radiofrequency Versus Cryoballoon Catheter Ablation for Paroxysmal Atrial Fibrillation: Durability of Pulmonary Vein Isolation and Effect on Atrial Fibrillation Burden: The RACE-AF Randomized Controlled Trial

Supplemental Digital Content is available in the text.

Background:

Recurrent paroxysmal atrial fibrillation (AF) after catheter ablation is presumably caused by failure to achieve durable pulmonary vein isolation (PVI). The primary methods of PVI are radiofrequency catheter ablation (RF) and cryoballoon catheter ablation (CRYO), but these methods have not been directly compared with respect to PVI durability and the effect thereof on AF burden (% of time in AF).

Methods:

Accordingly, we performed a randomized trial including 98 patients (68% male, 61 [55–67] years) with paroxysmal AF assigned 1:1 to PVI by contact-force sensing, irrigated radiofrequency catheter, or second-generation cryoballoon catheter. Implantable cardiac monitors were inserted ≥1 month before PVI for assessment of AF burden and recurrence, and all patients, irrespective of AF recurrence, underwent a second procedure 4 to 6 months after PVI to determine PVI durability.

Results:

In the second procedure, 152 out of 199 (76%) pulmonary veins (PVs) were found durably isolated after RF and 161 out of 200 (81%) after CRYO (P=0.32), corresponding to durable isolation of all veins in 47% of patients in both groups (P=1.0). Median AF burden before PVI was 5.4% (interquartile range, 0.5%–13.0%) versus 4.0% (0.6%–18.1%), RF versus CRYO (P=0.71), and reduced to 0.0% (0.0%–0.1%) and 0.0% (0.0%–0.5%), respectively (P=0.58)—a reduction of 99.9% (92.9%–100.0%) and 99.3% (85.9%–100.0%; P=0.36). AF burden after PVI significantly correlated to the number of durably isolated PVs (P<0.01), but 9 out of 45 (20%) patients with durable isolation of all veins had recurrence of AF within 4 to 6 months after PVI (excluding a 3-month blanking period).

Conclusions:

PVI by RF and CRYO produce similar moderate to high PVI durability. Both treatments lead to marked reductions in AF burden, which is related to the number of durably isolated PVs. However, for one-fifth of paroxysmal AF patients, complete and durable PVI was not sufficient to prevent even short-term AF recurrence.

Registration:

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03805555.

Experience and procedural efficacy of pulmonary vein isolation using the fourth and second generation cryoballoon: The shorter, the better?

BACKGROUND

The second-generation cryoballoon (CB2) provides effective and durable pulmonary vein isolation (PVI) associated with encouraging clinical outcome. The novel fourth-generation cryoballoon (CB4) incorporates a 40% shorter distal tip. This design change may translate into an increased rate of PVI real-time signal recording, facilitating an individualized ablation strategy using the time to effect (TTE).

METHODS AND RESULTS

Three hundred consecutive patients with paroxysmal or persistent atrial fibrillation were prospectively enrolled. The first 150 consecutive patients underwent CB2 based PVI (CB2 group) and the last 150 consecutive patients were treated with the CB4 (CB4 group). A total of 594/594 (100%, CB4) and 589/594 (99.2%, CB2) pulmonary veins (PVs) were successfully isolated utilizing the CB4 and CB2, respectively (p = .283). The real-time PVI visualization rate was 47% (CB4) and 39% (CB2; p = .005) and the mean freeze cycle duration 200 ± 90 s (CB4) and 228 ± 110 s (CB2; p < .001), respectively. The total procedure time did not differ between the groups (CB4: 64 ± 32 min) and (CB2: 62 ± 29 min, p = .370). No differences in periprocedural complications were detected.

CONCLUSIONS

A higher rate of real-time electrical PV recordings are seen using the CB4 as compared to CB2, which may facilitate an individualized ablation strategy using the TTE.

The advantages and disadvantages of the novel fourth-generation cryoballoon as compared to the second-generation cryoballoon in the current short freeze strategy

BACKGROUND

The novel fourth-generation cryoballoon (4^th-CB) is characterized by a shorter-tip that potentially facilitates better time-to-isolation (TTI) monitoring. We sought to clarify the advantages and disadvantages of the 4^th-CB compared to the second-generation cryoballoon (2^nd-CB) in pulmonary vein isolation (PVI).

METHODS

Forty-one and 49 consecutive atrial fibrillation patients underwent 2^nd-CB and 4th-CB PVIs using 28-mm balloons and short freeze strategies. When effective freezing was not obtained, the CB was switched to the other CB.

RESULTS

The rate of successful PVIs was significantly higher for 2^nd-CBs than 4^th-CBs (162/162[100%] vs. 178/193[92.2%] PVs, p < 0.0001). The difference was significant for lower PVs, especially right inferior PVs (RIPVs)(p = 0.005). In a total of 15 PVs in 11 patients, 4^th-CBs were switched to 2^nd-CBs, and 14/15(93.3%) PVs were successfully isolated. The balloon temperature tended to reach -55℃ more frequently with 2^nd-CBs than 4^th-CBs during RIPV ablations (15/41[36.6%] vs. 12/49[24.5%], p = 0.21). The TTI monitoring capability was significantly higher with 4^th-CBs than 2^nd-CBs (131/188[69.7%] vs. 83/160[51.9%] PVs, p = 0.0007). The difference was significant for right superior and left inferior PVs, but not for left superior PVs. Even if PVs requiring crossover were excluded, the total freeze duration (715±152 vs. 755±215 seconds, p = 0.31) tended to be shorter for 2^nd-CBs than 4^th-CBs. The incidence of phrenic nerve injury was similar for 2^nd-CB and 4th-CB ablation (0/41 vs. 2/49, p = 0.12) CONCLUSIONS: The 4^th-CB's shorter balloon tip enabled a significantly higher capability of TTI monitoring; however, it resulted in significantly lower rates of successful PVIs than the 2^nd-CB, especially for the RIPVs.

Disappearance pattern and the last remaining earliest pulmonary vein potential during cryoballoon ablation in predicting recurrence and conduction gap site of pulmonary veins

Electrophysiological studies have rarely evaluated the sites prone to pulmonary vein (PV) conduction gap during cryoballoon ablation (CBA) for atrial fibrillation (AF). In addition, no studies have analyzed the sequence of PV potentials just before PV isolation during CBA for AF. Of the 238 patients who underwent first-time CBA for paroxysmal AF, 115 PVs of 29 patients who underwent repeat session due to recurrence after the procedure were retrospectively evaluated in the study. We evaluated the disappearance pattern of PV potential and PV reconnection on intracardiac electrograms and investigated whether the conduction gap site of the PV was related to the last remaining earliest PV potential (EP) and sequence pattern during the first-time CBA. Time to isolation was observed in 81 PVs during the first-time CBA. At the repeat session, PV reconnection was only observed in 22 of 81 PVs. PV potentials disappeared with sequence changes in 36 PVs and without sequence changes in 38 PVs. Multivariate analysis demonstrated that disappearance of PV potentials without change in the EP site but with delay or disappearance of other PV potentials was independently associated with PV reconnection (12/22 PVs [55%] vs. 4/59 PVs [6.8%]; odds ratio 14.4; 95% confidence interval 3.75-55.5; p < 0.001). In 19 of 22 (86%) reconnected PVs, PV conduction gap sites at repeat ablation corresponded with the last remaining EP sites during first-time CBA. In conclusion, disappearance pattern of the PV potential and the last remaining EP during the CBA can predict PV reconnection and gap site.

Outcomes of cryoballoon or radiofrequency ablation in symptomatic paroxysmal or persistent atrial fibrillation

Aims

To evaluate the effectiveness and safety of cryoballoon ablation (CBA) compared with radiofrequency ablation (RFA) for symptomatic paroxysmal or drug-refractory persistent atrial fibrillation (AF).

Methods and results

Prospective cluster cohort study in experienced CBA and RFA centres. Primary endpoint was ‘atrial arrhythmia recurrence’, secondary endpoints were as follows: procedural results, safety, and clinical course. A total of 4189 patients were included: CBA 2329 (55.6%) and RFA 1860 (44.4%). Cryoballoon ablation population was younger, with fewer comorbidities. Procedure time was longer in the RFA group (P = 0.01). Radiation exposure was 2487 (CBA) and 1792 cGycm² (RFA) (P < 0.001). Follow-up duration was 441 (CBA) and 511 days (RFA) (P < 0.0001). Primary endpoint occurred in 30.7% (CBA) and 39.4% patients (RFA) [adjusted hazard ratio (adjHR) 0.85, 95% confidence interval (CI) 0.70–1.04; P = 0.12). In paroxysmal AF, CBA resulted in a lower risk of recurrence (adjHR 0.80, 95% CI 0.64–0.99; P = 0.047). In persistent AF, the primary outcome was not different between groups. Major adverse cardiovascular and cerebrovascular event rates were 1.0% (CBA) and 2.8% (RFA) (adjHR 0.53, 95% CI 0.26–1.10; P = 0.088). Re-ablations (adjHR 0.46, 95% CI 0.34–0.61; P < 0.0001) and adverse events during follow-up (adjHR 0.64, 95% CI 0.48–0.88; P = 0.005) were less common after CBA. Higher rehospitalization rates with RFA were caused by re-ablations.

Conclusions

The primary endpoint did not differ between CBA and RFA. Cryoballoon ablation was completed rapidly; the radiation exposure was greater. Rehospitalization due to re-ablations and adverse events during follow-up were observed significantly less frequently after CBA than after RFA. Subgroup analysis suggested a lower risk of recurrence after CBA in paroxysmal AF.

Trial Registration

ClinicalTrials.gov (NCT01360008), https://clinicaltrials.gov/ct2/show/NCT01360008.