Single freeze per vein strategy with the second-generation cryoballoon for atrial fibrillation: a propensity score-matched study between 180- and 240-s application time in a large cohort of patients

Recurrent atrial fibrillation after initial cryoballoon ablation: New perspectives for intensive ablation in right superior pulmonary vein ostium for atrial fibrillation

A significant proportion of patients with recurrent atrial fibrillation (AF) require repeat radiofrequency (RF) ablation after cryoballoon (CB) ablation. However, little is known about the pulmonary vein (PV) potential reconnection to left atrium and localization of gaps in the initial lesion sets following cryoablation in patients with recurrent AF. The data of 29 consecutive patients with repeat RF ablation for recurrent AF were analyzed. During the second ablation procedures, PV foci of AF were explored in 116 PVs by the CARTO system. All patients had complete PV isolation from initial cryoablation procedure. The fluoroscopy duration, mean cryoablation time and mean cryoablation frequency were lowest for the right superior pulmonary vein (RSPV) (58.69 ± 9.18 s, 185.10 ± 49.25 s and 1.07 ± 0.26; p = 0.024, p = 0.042 and p = 0.032). A significantly higher incidence of conduction gaps per patient was found for the RSPVs compared to the other PVs (p < 0.05 or p < 0.01). For RSPVs, it seemed that gaps were predominantly located at the anterior segment (22 gaps) and inferior segment (22 gaps). RSPV reconnection was independently related to a lower risk of major adverse events after the second ablation during follow up in the study patients (HR 0.275, 95%CI 0.078-0.967, p = 0.044). AF recurrence in patients after cryoablation is significantly associated with conduction gaps in the anterior and inferior segments of RSPVs. Various ablation strategies of close touch of CB on anterior and inferior segments of RSPV ostium, more freezing time and frequency for RSPV may help achieving durable PV isolation during follow up.

Effectiveness and Safety of Cryoablation in Patients With Atrial Fibrillation Episodes of <24 h Duration: A Propensity-Matched Analysis

Background: Paroxysmal atrial fibrillation (AF) is closely related to pathophysiologic processes and clinical outcomes. However, it is uncertain whether cryoablation of pulmonary veins isolation is effective and safe for patients with symptomatic and drug refractory AF episodes of <24-h duration.

Methods: The patients were designed into Group A (253 patients with paroxysmal AF episodes of <24-h duration) and Group B (253 patients with paroxysmal AF lasting for 24 h or longer) on a 1:1 basis by identical propensity scores. Mortality, stroke/transient ischemic attack (TIA), and complications relevant to the cryoablation procedure were compared, and recurrence of atrial tachyarrhythmia was analyzed for clinical independent predictors.

Results: The rate of atrial tachyarrhythmia recurrence was 21.74% in Group A and 30.04% in Group B, respectively (P = 0.042). At 12-month follow-up from the procedure, lower incidences of stroke/TIA endpoint of the patients were observed in Group A compared with Group B by Kaplan–Meier analysis [HR 0.34 (0.13–0.87), P = 0.025]. No significant differences in mortality and complications relevant to the cryoablation procedure were observed between Group A and Group B. Moreover, adjusted multivariable Cox regression analysis showed that <24-h paroxysmal AF type (HR 0.644, 95% CI: 0.455–0.913, P = 0.014) and left atrium diameter (LAD) (>40 mm) (HR 1.696, 95% CI: 1.046–2.750, P = 0.032) were independently associated with the incidence of recurrence of atrial tachyarrhythmia in the study.

Conclusion: Our findings indicated that <24-h paroxysmal AF type was obviously associated with an increased success rate of cryoablation and reduced incidence of stroke/TIA during the follow-up period. Therefore, there is superior effectiveness and similar safety in patients with AF episodes of <24-h duration compared with patients with longer paroxysmal AF duration.

Cryoballoon Ablation of Atrial Fibrillation Without Demonstration of Pulmonary Vein Occlusion-The Simplify Cryo Study

Background: The demonstration of pulmonary vein (PV) occlusion is routinely performed and considered a prerequisite for successful cryoballoon (CB) ablation of atrial fibrillation (AF). The purpose of this study was to assess the feasibility and impact on procedural parameters and outcome of a standardized procedural protocol without demonstrating PV occlusion. Methods and Results: Consecutive patients undergoing CB pulmonary vein isolation (PVI) were studied. After cMRI assessment, patients treated by PVI using a novel no-contrast (NC) protocol without routine contrast injections to demonstrate PV occlusion (NC group) were compared to patients undergoing PVI with contrast injections to demonstrate PV occlusion (standard group). One hundred patients with paroxysmal or persistent AF (age 61 ± 10 years, ejection fraction 59 ± 11%, left atrial volume index 37.2 ± 2.0 mL/m2) were studied. The NC protocol was feasible in 72 of 75 patients (96%). Total procedure time and fluoroscopy time were 64.0 ± 14.1 min and 11.0 ± 4.6 min in the NC group and 92.0 ± 25.3 min and 18.0 ± 6.0 min in the standard group, respectively (all p < 0.001). Dose area product was 368 ± 362 cGy*cm2 in the NC group compared to 1928 ± 1541 cGy*cm2 in the standard group (p < 0.001). Forty-five of 75 patients (60%) in the NC group and 16 of 25 patients (64%) in the standard group remained in stable sinus rhythm after a single PVI and a 1-year follow-up (p = 0.815). Conclusions: Performing CB ablation without using contrast injections to demonstrate PV occlusion was feasible, resulted in reduced radiation exposure, and increased the efficiency of the procedure.

Strategies to Improve the Outcome of Cryoballoon Ablation in the Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is a common arrhythmia contributing to severe outcomes, including cardiac dysfunction and stroke, and it has drawn great attention around the world. Drug therapies have been available for many years to terminate AF and control heart rate. However, the results from clinical studies on drug therapies have been discouraging. Mounting evidence indicates that radiofrequency catheter ablation (RFCA) is a safe and effective method to maintain sinus rhythm, especially in patients who are drug intolerant or for whom the drugs are ineffective, although it is a technically demanding and complex procedure. Fortunately, a novel application, cryoballoon ablation (CBA), with outstanding characteristics has been widely used. Great outcomes based on CBA have manifested its significant role in the treatment of AF. However, how to improve the safety and efficacy of CBA is a question that has not been well-answered. Would it be helpful to develop a different generation of cryoballoon? Is bonus freezing beneficial, or not? Is it better to prolong freezing time? Dose CBA combined with RFCA bring higher success rates? In this review, we comprehensively summarized useful applications for improving outcomes of CBA in AF patients.

Conversion of atrial fibrillation to sinus rhythm during cryoballoon ablation: A favorable and not unusual phenomenon during second-generation cryoballoon pulmonary vein isolation

BACKGROUND

The prevalence and the clinical impact of conversion of atrial fibrillation (AF) to sinus rhythm (SR) during cryoballoon ablation (CB-A) are unknown.

OBJECTIVE

The purpose of this study was to evaluate the prevalence of restoration of SR during CB-A and the clinical impact of this phenomenon.

METHODS

Between January 2012 and September 2018, all patients who experienced conversion of AF to SR during CB-A were included. This group was subsequently matched for gender, age, type of AF, diagnosis-to-ablation time, and left atrial size with patients who underwent CB-A and did not experienced conversion of AF to SR. After discharge, patients were scheduled for follow-up visits at 1, 3, 6, and 12 months and 24 hours Holter recordings were obtained at each follow-up visit. All documented AF episodes of >30 seconds were considered as recurrence. A 3 month post-procedural blanking period (BP) was applied.

RESULTS

A total of 1559 patients underwent pulmonary veins isolation by CB-A between January 2012 and September 2018; among them, 58 patients (3.7%) experienced restoration of SR during CB-A. In total, 53 patients (41 males [77.3%], mean age 61.4 ± 13.3 years) were included in the case group. During CB-A, restoration of SR occurred more frequently during right-side PVs applications (right inferior pulmonary vein 39.6%, right superior pulmonary vein 30.2%). If considering a BP, at 2 year follow-up, freedom from recurrences was 86.5% in the case group and 68.0% in the control group (P = .036).

CONCLUSION

Conversion of AF to SR is a favorable and relatively frequent phenomenon during cryoballoon pulmonary vein isolation ablation.

Current Status of Atrial Fibrillation Ablation with Balloon Strategy

Catheter ablation of atrial fibrillation (AF) has been established worldwide and is recommended for symptomatic paroxysmal AF patients according to international guidelines. Importantly, the cornerstone of any AF ablation represents pulmonary vein isolation (PVI). Traditional radiofrequency (RF) point by point ablation within a 3D electroanatomic left atrial (LA) map requires profound understanding of LA anatomy and electrophysiology. This ablation strategy can be highly efficient and safe if performed in experienced hands and centers. However, procedural complexity causes a long learning curve and has limited its wide spread utilization. In contrast, balloon based PVI ablation strategies are based on an anatomic principle. Currently, two balloon types (cryoballoon and laserballoon) have been adopted to clinical routine. Both balloons are positioned at the target PV and circumferential energy ablation is enabled. This simplified anatomic approach facilitates reaching the procedural endpoint of PVI and demonstrated less operator dependency. Therefore, balloon PVI appears to be associated with improved procedural reproducibility and safety. Importantly, large scale randomized trials proved non-inferiority of balloon guided AF ablation (cryothermal and laser energy) vs. experienced operators using traditional “gold standard” RF ablation in paroxysmal and persistent AF. Ongoing technological refinements of both balloons as well as the introduction of novel energy dosing strategies and ablation targets may potentially impact the current way of ablating AF in future. This review will summarize current clinical experience of contemporary balloon devices and will look into future developments.

Optimizing ablation duration using dormant conduction to reveal incomplete isolation with the second generation cryoballoon: A randomized controlled trial

Introduction

Efficacy of cryoballoon ablation depends on balloon‐tissue contact and ablation duration. Prolonged duration may increase extracardiac complications. The aim of this study is to determine the optimal additional ablation duration after acute pulmonary vein isolation (PVI).

Methods

Consecutive patients with paroxysmal AF were randomized to three groups according to additional ablation duration (90, 120, or 150 seconds) after acute PVI (time‐to‐isolation). Primary outcome was reconnection/dormant conduction (DC) after a 30 minutes waiting period. If present, additional 240 seconds ablations were performed. Ablations without time‐to‐isolation <90 seconds, esophageal temperature <18°C or decreased phrenic nerve capture were aborted. Patients were followed with 24‐hour Holter monitoring at 3, 6, and 12 months.

Results

Seventy‐five study patients (60 ± 11 years, 48 male) were included. Reconnection/DC per vein significantly decreased (22%, 6% and 4%) while aborted ablations remained stable (respectively 4, 5, and 7%) among the 90, 120, and 150 seconds groups. A shorter cryo‐application time, longer time‐to‐isolation, higher balloon temperature and unsuccessful ablations predicted reconnection/DC. Freedom of atrial fibrillation was, respectively, 52, 56, and 72% in 90, 120, and 150 seconds groups ( P = 0.27), while repeated procedures significantly decreased from 36% to 4% ( P = 0.041) in the longer duration group compared to shorter duration group (150 seconds vs 90 seconds group). In multivariate Cox‐regression only reconnection/DC predicted recurrence.

Conclusion

Prolonging ablation duration after time‐to‐isolation significantly decreased reconnection/DC and repeated procedures, while recurrences and complications rates were similar. In a time‐to‐isolation approach, an additional ablation of 150 seconds ablation is the most appropriate.

The fourth cryoballoon generation with a shorter tip to facilitate real-time pulmonary vein potential recording: Feasibility and safety results

INTRODUCTION

Time-to-isolation (TTI) guided ablation protocols have been developed to ensure durable pulmonary vein isolation (PVI) in cryoballoon ablation (CBA). The aim was to determine the feasibility and safety of the fourth generation cryoballoon (CBG4) with a shortened tip.

METHODS AND RESULTS

Consecutive patients scheduled for initial atrial fibrillation (AF) ablation were prospectively included. PVI with the 28 mm CBG4 and the latest 20 mm spiral-mapping catheter (SMC) was performed. A total of 302 pulmonary veins (PVs) in 76 patients (64.8 ± 10.4 years, paroxysmal AF 49%) were treated with 617 applications. Left atrium (LA) time, fluoroscopy time, and dose-area product were 65.5 ± 19.2 minutes, 14.6 ± 5.6 minutes, and 1094 (738; 2097) cGy·cm² , respectively. PVI in cryoballoon technique was achieved in 302 of 302 (100%) PVs. TTI was determined in 256 (84.8%) of PVs. The mean TTI was 45.3 ± 26.4 seconds. Single-shot isolation was achieved in 247 (82%) PVs. In 6 of 302 (2.0%) PV the SMC was changed to a stiff wire to isolate the PV because of instability, and in 17 of 302 (5.6%) of PVs, the 23 mm CB was used to isolate. No radiofrequency touch-up applications were applied. The mean nadir balloon temperature was -44.8°C ± 6.6°C. Balloon dislodgement during positioning occurred in 3 of 617 (0.5%) applications without complications. One PN palsy occurred which resolved until discharge. One patient suffered from the inflammatory syndrome.

CONCLUSION

The CBG4 with a shorter distal tip seems to be safe and effective, and allows determining the TTI in 84.8% of PVs. In case of balloon instability, the exchange of the SMC to a stiff wire or, in small PV, the 23 mm cryoballoon facilitate PVI.

Single 3-min freeze per vein ablation strategy with the second-generation cryoballoon for atrial fibrillation in a large cohort of patients: long term outcome after a single procedure

PURPOSE

The purpose of the present study was to assess the long-term success rate of a single 3-min freeze per vein ablation strategy in the setting of pulmonary vein isolation (PVI) by means of second-generation cryoballoon (CB-A; Arctic Front Advance, Medtronic, Minneapolis, MN, USA) in a large cohort of patients.

METHODS

Three hundred and one patients with drug resistant atrial fibrillation (AF) having undergone PVI by means of CB-A using a single 3-min freeze per vein ablation strategy were included in the analysis.

RESULTS

Paroxysmal AF (PAF) was documented in 70.8% of the patients, while 29.2% presented with persistent AF (PersAF). The mean number of CB applications was 1.09 ± 0.3 in the left superior pulmonary vein (LSPV), 1.04 ± 0.2 in the left inferior pulmonary vein (LIPV), 1.12 ± 0.3 in the right superior pulmonary vein (RSPV), and 1.12 ± 0.3 in the right inferior pulmonary vein (RIPV). All PVs were successfully isolated with a 28-mm CB-A only. After a mean follow-up of 38.1 ± 7.5 months, 207 (68.8%) patients were free of atrial tachyarrhythmia (ATa) recurrences following a single procedure. Specifically, 72.8% of patients presenting with PAF and 59.1% of individuals with PersAF did not experience a recurrence.

CONCLUSIONS

A single 3-min freeze per vein strategy is effective in treating AF on a long term follow-up of 38 months. Specifically, it can afford freedom from ATa recurrences in 72.8% of patients affected by PAF and 59.1% of patients initially presenting with PersAF after a single CB-A procedure.

The Impact of Advances in Atrial Fibrillation Ablation Devices on the Incidence and Prevention of Complications

The number of patients with atrial fibrillation currently referred for catheter ablation is increasing. However, the number of trained operators and the capacity of many electrophysiology labs are limited. Accordingly, a steeper learning curve and technical advances for efficient and safe ablation are desirable. During the last decades several catheter-based ablation devices have been developed and adapted to improve not only lesion durability, but also safety profiles, to shorten procedure time and to reduce radiation exposure. The goal of this review is to summarise the reported incidence of complications, considering device-related specific aspects for point-by-point, multi-electrode and balloon-based devices for pulmonary vein isolation. Recent technical and procedural developments aimed at reducing procedural risks and complications rates will be reviewed. In addition, the impact of technical advances on procedural outcome, procedural length and radiation exposure will be discussed.