Cryoballoon Best Practices II: Practical guide to procedural monitoring and dosing during atrial fibrillation ablation from the perspective of experienced users

Real-world evidence demonstrates an appropriate atrial fibrillation population for hybrid convergent approach versus stand-alone cryoballoon ablation: A long-term safety and efficacy study

INTRODUCTION

A hybrid convergent approach (endocardial and epicardial ablation) demonstrated superior effectiveness in a recent randomized study for long-standing persistent atrial fibrillation (LSPAF). Yet, there is a lack of real-world, long-term evidence as to which patients are best candidates for a hybrid convergent approach compared to standard endocardial cryoballoon pulmonary vein isolation (CB PVI).

METHODS AND RESULTS

This single-center, retrospective analysis spanning from 2010 to 2015 compared two distinctly different atrial fibrillation (AF) cohorts; one treated with stand-alone cryoablation and one treated with a hybrid convergent approach. Baseline characteristics described candidates for each approach. The following criteria were utilized to determine CB PVI candidacy: (1) paroxysmal AF (PAF) (stage 3A) with failed class I/III antiarrhythmic drug (AAD) or (2) persistent/LSPAF (stage 3B/3C/3D) with failed class I/III AAD unwilling to undergo hybrid procedure. Selection criteria for the hybrid procedure included: (1) PAF refractory to both class I/III AAD and prior CB PVI (stage 3D) or (2) persistent/LSPAF (stage 3B/3C/3D) with failed class I/III AAD agreeable to hybrid procedure. Prior sternotomy was excluded. Serial electrocardiograms and continuous monitoring evaluated primary efficacy outcome of time-to-first recurrence of atrial arrhythmia after a 90-day blanking period. Secondary outcomes were procedure-related complications and AAD use (at discharge, 12, and 36 months). Kaplan-Meier methods evaluated arrhythmia recurrence. Of 276 patients, 197 (64.2 ± 10.6 years old; 66.5% male; 74.1% 3A-PAF; 18.3% 3B/3D-persistent AF; 1.0% 3C-LSPAF; 6.6% undetermined) underwent CB PVI and 79 (61.4 ± 8.1 years old; 83.5% male; 41.8% 3D-PAF; 45.5% 3B/3D-persistent AF; 12.7% 3C/3D-LSPAF) underwent hybrid procedure. Arrhythmia freedom through 36 months was 55.2% for CB PVI and 50.4% for hybrid (p = .32). Class I AAD utilization at discharge occurred in 38 (19.3%) patients in the CB PVI group and 5 (6.3%) patients in the hybrid group (p = .01). CB PVI class I AAD utilization at 12 months occurred in 14 (9.0) patients versus 0 patients for hybrid convergent (p = .004). Patients with one or more adverse event were as follows: two (1.0%) in the CB PVI group (both transient phrenic nerve palsy) and three (3.7%) in the hybrid group (two with significant bleeding and one with wound infection) (p = .14).

CONCLUSION

This study demonstrated that patients with more complex forms of AF (3D-PAF or 3B/3C/3D-persistent/LSPAF) could be well managed with a convergent approach. In a real-world evaluation, outcomes match safety and efficacy thresholds achieved for patients with earlier, less complex AF etiologies treated by CB PVI alone.

A New Hope for the Treatment of Atrial Fibrillation: Application of Pulsed-Field Ablation Technology

In recent years, the prevalence of and mortality associated with cardiovascular diseases have been rising in most countries and regions. AF is the most common arrhythmic condition, and there are several treatment options for AF. Pulmonary vein isolation is an effective treatment for AF and is the cornerstone of current ablation techniques, which have one major limitation: even when diagnosed and treated at a facility that specializes in ablation, patients have a greater chance of recurrence. Therefore, there is a need to develop better ablation techniques for the treatment of AF. This article first compares the current cryoablation (CBA) and radiofrequency ablation (RFA) techniques for the treatment of AF and discusses the utility and advantages of the development of pulsed-field ablation (PFA) technology. The current research on PFA is summarized from three perspectives, namely, simulation experiments, animal experiments, and clinical studies. The results of different stages of experiments are summarized, especially during animal studies, where pulmonary vein isolation was carried out effectively without causing injury to the phrenic nerve, esophagus, and pulmonary veins, with higher safety and shorter incision times. This paper focuses on a review of various a priori and clinical studies of this new technique for the treatment of AF.

In vivo safety and pulmonary vein isolation performance of a new cryoballoon for the treatment of atrial fibrillation

BACKGROUND

Cryoablation to achieve pulmonary vein (PV) isolation has become one of the standard approaches for atrial fibrillation (AF) ablation. The Arctic Front series cryoballoon and Achieve circular mapping catheter (Medtronic) inherently possess design defects that have been associated with unfavorite clinical outcomes. Lately, a new cryoablation system (Nordica Cryoablation System, Synaptic Medical) was developed with improved design of the cryoballoon and circular mapping catheter to address the inadequacies of current cryoablation technology. An animal study was conducted to test the efficacy and safety in performing PVI with the Nordica Cryoablation System.

METHODS

Pulmonary vein isolation with the Nordica Cryoablation System was performed on 12 PVs of six healthy canines. Acute PVI and peri-procedural complications were recorded. All animals underwent a repeat EP study at least 4 weeks after index procedures followed by pathological and histological assessments of the heart and collateral/downstream organs after planned euthanasia.

RESULTS

Acute PV isolation was achieved in all targeted PVs with 50% of PVs being isolated with a single cryoablation application. There were no major peri-procedural complications or device malfunction events. All PVs remained isolated after 29-30 days follow-up. Histological examination showed transmural cryo-lesions at treated sites with minimal inflammation, neovascularization, and neointima formation but no significant injury to adjacent tissue or embolization in downstream organs.

CONCLUSION

Acute and durable PVI can be achieved by using the novel Nordica Cryoablation System. Ablation with this new cryoablation system is associated with transmural lesions at targeted myocardium but creates no injury to the collateral tissues or downstream organs.

Integrated dilator-needle transseptal crossing device in atrial fibrillation cryoballoon ablation procedures

INTRODUCTION

In cryoballoon ablation (CBA) procedures, transseptal access (TSA) is generally achieved using a standard sheath and needle system that is exchanged for the cryoballoon delivery sheath and dilator over a long wire. Sheath exchange has been related with air embolic events. Recently, an integrated dilator-needle system assembled to the cryoballoon sheath was introduced. We aimed to evaluate the efficacy and safety of an integrated TSA tool compared with the traditional approach in atrial fibrillation CBA procedures.

METHODS

Patients scheduled for CBA procedures were randomized 1:1 to traditional TSA (t-TSA) or integrated TSA (i-TSA). TSA time was defined as time from superior vena cava to LA insertion of the cryoballoon delivery sheath, after sheath exchange (t-TSA) or directly (i-TSA).

RESULTS

Ninety-seven patients (76 males, mean age 59 ± 10 years) were randomized, 48 patients underwent t-TSA, and 49 i-TSA. Mean TSA time was 5 min 59 s ± 5 min 36 s in the t-TSA group and 2 min 59 s ± 2 min 14 s in the i-TSA group (p < .001). Total fluoroscopy time, skin-to-skin procedure time, and LA dwell time were respectively 15 ± 6, 69 ± 16, and 44 ± 12 min in the t-TSA group and 13 ± 6, 65 ± 15, and 43 ± 11 min in the i-TSA group (p = ns). No clinically significant acute complications related to TSA were noted in both cohorts.

CONCLUSION

This is the first randomized study comparing both TSA approaches. TSA in CBA procedures using this integrated tool enables a safe and efficient workflow, reducing TSA time and avoiding sheath exchange.

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

INTRODUCTION

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Incidence of cryoballoon expansion dislodgement during pulmonary vein isolation-An underappreciated frequent cause of incomplete isolation

BACKGROUND

Cryoballoon ablation for atrial fibrillation (AF) requires adequate contact between the pulmonary vein (PV) antrum and cryoballoon. The surge of intraballoon pressure during the initial phase of ablation may change the balloon's shape and compliance, resulting in balloon dislodgement and loss of PV occlusion. Without continuous monitoring, this phenomenon is often undetected but can be associated with incomplete PV isolation (PVI).

METHODS

Primary cryoablation of AF was performed in 15 patients. PV occlusion status pre- and post-freezing were analyzed with intracardiac echocardiography (ICE) and dielectric imaging-based occlusion tool (DIOT) to calculate the incidence of expansion dislodgement of cryoballoon.

RESULTS

A total of 105 cryoablation applications were performed on 57 veins, including three common ostiums of left pulmonary veins. In the evaluation of PV occlusion, both modalities reported consistent results in 86.7% of the assessments. Despite complete PV occlusion before ablation, peri-balloon leak after initiation of freezing was detected by ICE in 5/22 (22.7%) applications and by DIOT in 8/25 (32%) applications.

CONCLUSION

Incidence of expansion dislodgement of the cryoballoon was detected in one-fourth to one-third of cryoablation applications depending on the imaging modality used, which was clinically frequent and significant.

Initial clinical experience of atrial fibrillation ablation guided by a cryoballoon-compatible, magnetic-based circular catheter

INTRODUCTION

The circular catheter compatible with current cryoballoon system for atrial fibrillation (AF) ablation is exclusively sensed by impedance-based electro-anatomical mapping (EAM) system, limiting the accuracy of maps. We aim to investigate the feasibility and safety of a magnetic-based circular mapping catheter for AF ablation with cryoballoon.

METHODS

Nineteen consecutive patients who underwent pulmonary vein isolation (PVI) with cryoballoon for paroxysmal or persistent AF were included. EAMs of left atrium (LA) created by the LASSOSTAR™NAV catheter (Lassostar map) before and after PVI were compared to that generated by a high-density mapping catheter (Pentaray map) from different aspects including structural similarity, PV angle, LA posterior wall (LAPW) and low voltage areas (LVAs), and the amplitude of far field electrograms (FFEs) recorded by catheters.

RESULTS

All patients had successful PVI without major complications. With similar mapping time and density, the LA volume calculated from the Pentaray map and Lassostar map were comparable. There were no significant differences in PV angle of all PVs and PW area (16.8 ± 3.2 vs. 17.1 ± 2.8, p = .516) between Pentaray map and Lassostar map. High structural similarity score was observed between two maps (0.783 in RAO/LAO view and 0.791 in PA view). Lassostar map detected lesser but not statistically significant extension of LVA (13.9% vs. 18.3%, p = .07). Amplitude of FFE was larger at the right superior PV on Lassostar map (0.21 ± 0.16 vs. 0.14 ± 0.11 mV, p = .041) compared to that on the Pentaray map.

CONCLUSION

In our initial experience, PVI with cryoballoon and magnetic-based circular LASSOSTAR™NAV catheter was safe and effective based on the accurate LA geometry it created.

The Influence of Pulmonary Veins' Anatomic Features and Catheter Coaxiality on Cryoballoon Ablation Results for Paroxysmal Atrial Fibrillation

A total of 172 consecutive patients with sympathetic paroxysmal atrial fibrillation who received cryoballoon (CB) ablation from 2020 to 2021 were retrospectively analyzed in this study. Catheter coaxiality and anatomic features of pulmonary veins (PVs) on computed tomography images were explored by several parameters and their influence on the cryoablation results was then analyzed. The rate of incomplete CB occlusion was significantly higher for inferior than superior PVs. A multivariate analysis revealed that a short distance (<6.3 mm) from PV ostium to first branch (D-PVB) and a small angle (<32.5°) of first branch were independent predict factors for an incomplete CB occlusion in right inferior PVs (RIPVs). A combination of D-PVB and angle of first branch could elevate the predictor value for an incomplete balloon occlusion with a sensitivity of 0.85 and specificity of 1.0 for RIPVs. For PVs with a perfect balloon occlusion, the best catheter coaxiality was observed in right superior PV while the worst catheter coaxiality was observed in RIPV. A more aggressive catheter manipulation with a "7" or "reverse-U" shape of long sheath could obtain a better catheter coaxiality compared with conventional manipulation strategy for RIPVs. In Conclusion, a short D-PVB and a small angle of first branch were independent predict factors for an incomplete CB occlusion in RIPVs. A more aggressive catheter manipulation strategy was recommended to achieve a complete balloon occlusion and a better catheter coaxiality for RIPVs.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Albumin as a Prognostic Marker for Atrial Fibrillation Recurrence following Cryoballoon Ablation of Pulmonary Venous

Introduction: Atrial fibrillation (AF) recurrence following pulmonary vein isolation (PVI) ablation has clinical significance. Identifying risk factors for AF recurrence is important. We investigated serum albumin (SA) levels (g/dL) as a prognostic factor for the recurrence of AF following cryoballoon PVI ablation. Methods: We included patients who underwent cryoballoon PVI ablation at our institution between the years 2013 and 2018. The primary outcome was recurrence of AF during follow up. Results: Our cohort consisted of 126 patients (67% males, mean age 61.8 ± 10.0 years). The pattern of AF amongst the cohort was paroxysmal in 62.5%, persistent in 25.4%, and longstanding persistent in 6.3%. Those with lower SA levels had a mean AF duration significantly less than those with higher SA levels (2.81 years, 7.34 years, and 6.37 years for SA levels of <3.8, 3.8−4.1, and ≥4.1, respectively; p = 0.003). Patients with lower SA levels were significantly more likely to have had more previous cardioversions and a larger left atrial area and volume. The mean follow-up was 380 days, in which the AF recurrence rate was 20.6%. Patients with lower SA level had significantly more AF recurrences (47.4%, 16.7%, and 2.2% for SA levels of <3.8, 3.8−4.1, and ≥4.1, respectively; p < 0.001). Upon multivariate analysis, an SA level < 3.8 was associated with a higher risk of AF recurrence (OR = 5.422 95% CI 1.134; 25.910; p < 0.001). Conclusion: SA levels were found to be a strong independent marker for AF recurrence following PVI ablation.

Effectiveness and safety of a time to isolation strategy of cryoballoon ablation of atrial fibrillation: A systematic review and meta-analysis

AIM

We conducted a systematic review and meta-analysis of randomized and observational studies with a control group to evaluate the effectiveness and safety of a time to isolation (TTI)-based strategy of cryoballoon ablation (CBA) in the treatment of atrial fibrillation (AF).

METHODS

Three electronic databases (MEDLINE, Cochrane Central Register of Controlled Trials, and Embase) without language restrictions were searched. The intervention assessed was a TTI-based strategy of CBA in the treatment of AF. TTI was defined as the time from the start of freezing to the last recorded pulmonary veins' potential. The comparison of interest was intended conventional protocol of CBA. The primary endpoint was freedom from atrial arrhythmia.

RESULTS

Nine studies were deemed eligible (N = 2289 patients). Eight studies reported freedom from atrial arrhythmia and pooled results showed a marginally similar success rate between the two protocols (odds ratio [OR]: 1.24; 95% confidence interval [CI]: 0.98-1.56). A prespecified subgroup analysis verified that a high dose TTI strategy (with >120 s duration of cryotherapy post-TTI) compared to the conventional protocol could significantly increase the patients without atrial arrhythmia during follow-up (OR: 1.39; 95% CI: 1.05-1.83). TTI strategy could also significantly decrease total procedure time (SMD: -26.24 min; 95% CI: -36.90 to -15.57) and phrenic nerve palsy incidence (OR: 0.49; 95% CI: 0.29-0.84).

CONCLUSION

Moderate confidence evidence suggests that an individualized CBA dosing strategy based on TTI and extended (>2 min post-TTI) duration of CBA is accompanied by fewer recurrences post-AF ablation.

Use of a novel integrated dilator-needle system in cryoballoon procedures: a zero-exchange approach

BACKGROUND

Recently, a novel integrated dilator-needle system (AcQCross Qx, Acutus Medical) was introduced to reduce the number of exchanges for a transseptal access. This system can be used in combination with large bore sheaths. In this pilot study, we evaluated the safety and efficacy of a zero-exchange approach with the AcQCross system in cryoballoon procedures.

METHODS

In this retrospective single-center study, we included 40 patients (AcQCross: n = 20; control group: n = 20) who underwent a cryoballoon procedure for the treatment of atrial fibrillation. In the AcQCross and control group, patients underwent ablation with POLARx (Boston Scientific) and Arctic Front Advance Pro (AFA-Pro, Medtronic) in equal numbers (n = 10). In the AcQCross group, the AcQGuide Max sheath (Acutus Medical) was used in all POLARx cases.

RESULTS

The baseline characteristics of the study population were comparable between groups. In the AcQCross group, there was a reduction in procedure time (49.7 ± 9.0 min vs. 59.6 ± 8.1 min, P < 0.001) and time from puncture until balloon delivery (15.5 ± 6.8 min vs. 21.5 ± 7.4 min, P = 0.01) in comparison with the control group. The balloon in body time, fluoroscopy time, number of cryoapplications, and biophysical parameters were similar between groups. There was one temporary phrenic nerve injury in the AcQCross group. Importantly, no signs of air embolism were noted with the AcQGuide Max sheath.

CONCLUSIONS

The use of the novel AcQCross system improves procedural efficacy in cryoballoon procedures by reducing the number of exchanges.

Left Atrial Function Post Radiofrequency and Cryoballoon Ablation Assessed by Volume-Pressure Loops

Background

Left atrial (LA) function is linked to atrial fibrillation (AF) pathogenesis. AF catheter ablation decreases disease burden with potentially favorable effects on cardiac function. Atrial volume-pressure loops can optimally assess the LA function.

Objective

To investigate changes in LA function by volume-pressure loops after paroxysmal AF ablation and explored potential differences between the radiofrequency and cryoballoon ablation.

Methods

We analyzed 44 patients undergoing paroxysmal AF ablation from 2 centers, 22 treated with radiofrequency and 22 with cryoablation. Pre- and post-procedure, all patients underwent a real-time three-dimensional transthoracic ECG to evaluate LA volume, while simultaneously recording LA pressure following transseptal puncture. Volume-pressure loops pre- and post-procedure were created by paired data. Areas of A-loop (LA booster pump function) and V-loop (LA reservoir function), and the stiffness constant determining the slope of the exponential curve during LA filling were calculated.

Results

Average LA pressure, A-wave amplitude, and V-wave amplitude were increased post-procedurally (p < 0.001). Overall, A-loop area decreased (p = 0.001) and V-loop area tended to increase (p = 0.07). The change in both A-loop and V-loop areas was similar between radiofrequency- and cryoballoon-treated patients (p = 0.18 and p = 0.52, respectively). However, compared with cryoballoon-treated patients, radiofrequency-treated patients had higher increase in the stiffness constant (b = 0.059; 95% CI: 0.022–0.096; p = 0.006).

Conclusion

AF catheter ablation by the radiofrequency or cryoballoon is associated with the decrease of the booster pump function and increase of the reservoir function. Moreover, there is a post-procedural increase of LA pressure which is associated with an acute increase in LA stiffness in radiofrequency ablation, but not in cryoablation.

Cryoballoon ablation for paroxysmal atrial fibrillation in Japan: 2-year safety and efficacy results from the Cryo AF Global Registry

Purpose

Catheter ablation is a recommended rhythm control therapy after failed or intolerant antiarrhythmic drug (AAD) treatment for patients with atrial fibrillation (AF). This study evaluates clinical performance and safety of pulmonary vein isolation (PVI) using the cryoballoon (Arctic Front Advance) in Japan.

Methods

Cryo AF Global Registry is a prospective, multi-center registry. Patients with paroxysmal AF (PAF) were treated at 10 Japanese hospitals. Efficacy was evaluated by freedom from a ≥ 30-s recurrence of AF/atrial flutter (AFL)/atrial tachycardia (AT), AF-related symptoms, and quality of life using the EQ-5D-3L questionnaire. The safety endpoint was serious device- and procedure-related adverse events.

Results

The study included 352 patients with PAF (65 ± 10 years of age, 36% female, 36% without prior failure of AAD). Mean duration since first diagnosis of AF was 3.0 ± 5.5 years. Serious device- and procedure-related adverse event rate was 2.6% (95% CI: 1.2–4.8%). Freedom from AF/AFL/AT was 88.5% (95% CI: 84.7–91.4%) at 12 months and 86.7% (95% CI: 81.1–90.8%) at 24 months. The number of patients with ≥ 1 AF symptom was significantly decreased from 88% at enrollment to 22% (p < 0.01) at 12-month follow-up. General quality of life using EQ-5D did not improve significantly after 12 months in the summary score. However, in the visual analog scale score, there was improvement (5.8 ± 18.4; p < 0.01).

Conclusions

This study demonstrates that cryoablation used for PVI is a safe and effective treatment in real-world use for patients with PAF in Japan.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10840-022-01132-0.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

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

Supplemental Digital Content is available in the text.

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.

New Minimally Invasive and Tailor-Made Strategy for Cryoballoon Ablation in Patients With Paroxysmal Atrial Fibrillation

BACKGROUND

The optimal dosage for cryoballoon ablation (CBA) of atrial fibrillation (AF) is still unknown.

OBJECTIVE

This study aimed to evaluate the clinical implications of a reduction in the freezing duration to <180 seconds during CBA guided by the time to the target temperature.

METHODS

This study enrolled 325 consecutive paroxysmal AF patients who underwent CBA. It was a retrospective observational study in a single centre. It compared 164 patients who underwent a tailor-made CBA procedure (group T) with 161 who had a standard CBA procedure (group S). In group T, the freezing duration was reduced to 150 seconds when the temperature reached ≤ -40 °C within 40 seconds. Furthermore, it was reduced to 120 seconds when it reached ≤ -50 °C within 60 seconds. In the other patients, the freezing duration was 180 seconds, except for excessive freezing of ≤ -60 °C and/or emergent situations while monitoring the oesophageal temperature, and for phrenic nerve injury, as in group S.

RESULTS

In group T, 89 patients (83%) underwent CBA with a reduction in the freezing duration. The total freezing time for each pulmonary vein was significantly shorter in group T than group S, and the total procedure time in group T decreased by an average of 4 minutes compared with group S. The rate of requiring additional radio frequency ablation following the CBA was significantly lower in group T than group S. The AF-free survival rate during the follow-up period (median, 366 days) was similar between the two groups.

CONCLUSION

The safety and efficacy of the new CBA strategy were non-inferior to the standard procedure.

Earliest pulmonary vein potential-guided cryoballoon ablation is associated with better clinical outcomes than conventional cryoballoon ablation: A result from two randomized clinical studies

INTRODUCTION

With regard to short-term outcome in atrial fibrillation (AF), the benefit of cryoballoon ablation (CBA) by pressing a balloon against the earliest pulmonary vein (PV) potential site during PV isolation (earliest potential [EP]-guided CBA) has been previously demonstrated. The present study aimed to evaluate the long-term outcome of the EP-guided CBA.

METHODS AND RESULTS

This study included 136 patients from two randomized studies, who underwent CBA for paroxysmal AF for the first time. Patients were randomly assigned to the EP-guided and conventional CBA groups in each study. In the EP-guided CBA group, we pressed a balloon against the EP site when the time-to-isolation (TTI) after cryoapplication exceeded 60 and 45 s in the first and second studies, respectively. We compared the clinical outcomes for 1 year after the procedure between the EP-guided CBA group (68 patients) and the conventional CBA group (68 patients). The primary endpoint was the recurrence of atrial arrhythmia after ablation. No significant differences in baseline characteristics were observed between the two groups. Compared with the conventional CBA group, the EP-guided CBA group had a significantly higher success rate at TTI ≤ 90 s (98.5% vs. 90.0%, p < .001); lower touch-up rate and total cryoapplication; and shorter procedure time, and fluoroscopy time. The recurrence at 1 year after ablation was significantly lower in the EP-guided CBA group than in the conventional CBA group (6.0% vs. 19.4%; p = .019).

CONCLUSIONS

The EP-guided CBA approach can facilitate the ablation procedure and achieve low recurrence at 1 year after ablation.

Primary results of the Spanish Cryoballoon Ablation Registry: acute and long-term outcomes of the RECABA study

Cryoablation is safe and effective for the treatment of atrial fibrillation (AF) in controlled clinical trials, but contemporary real-world usage and outcomes are limited. The Report of the Spanish Cryoballoon Ablation Registry (RECABA) was designed to evaluate acute and 12-month outcomes of cryoballoon ablation for the treatment of AF in Spain. Patients from 27 Spanish centers were prospectively enrolled. Patients were treated with cryoballoon ablation and managed according to standard of care protocols at each center. The primary endpoint was ≥ 30 s freedom from AF at 12-month after a 3-month blanking period. Secondary endpoints included a description of patient characteristics, cryoablation procedural strategy and safety, and predictors of efficacy. In total, 1742 patients (71.4% PAF, 68.8% male, mean age 58.02 ± 10.40 years, 76.1% overweight or obese, CHA₂DS₂-VASc index 1.40 ± 1.28) were enrolled. Patients received 7.2 ± 2.67 cryo-applications. PV potentials could be detected in 61% of the PVs during ablation, with a mean time to block of 52.9 ± 37.02 s. Acute PVI was observed in 97% of PVs with 75.8% isolated with the first cryo-application. Mean procedural time was 113 ± 41 min. Acute complications occurred in 4.4% of the cases. With follow-up in 1628 patients, AF-free survival was 78.5% (PAF: 80.6% vs PersAF 73.3%; p < 0.001). Left atrium enlargement, female sex, non-PAF, and early recurrence were independent predictors of AF recurrence (p < 0.05). RECABA provides detailed insight into current dosing practices and demonstrates cryoablation is safe and effective in real-world use.ClinicalTrials.gov number: NCT02785991.

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.

Advances in Atrial Fibrillation Ablation: Energy Sources Here to Stay

Energy sources used for catheter ablation of atrial fibrillation (AF) ablation have undergone an exceptional journey over the past 50 years. Traditional energy sources, such as radiofrequency and cryoablation, have been the mainstay of AF ablation. Novel investigations have led to inclusion of other techniques, such as laser, high-frequency ultrasound, and microwave energy, in the armamentarium of electrophysiologists. Despite these modalities, AF has remained one of the most challenging arrhythmias. Advances in the understanding of electroporation promise to overcome the shortcomings of conventional energy sources. A thorough understanding of the biophysics and practical implications of the existing energy sources is paramount.

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.

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.

Safety and efficacy of cryoballoon ablation for the treatment of paroxysmal and persistent AF in a real-world global setting: Results from the Cryo AF Global Registry

BACKGROUND

Cryoballoon ablation is a commonly used approach to treat patients with atrial fibrillation (AF).

OBJECTIVES

Report on the safety and efficacy of cryoballoon ablation for the treatment of AF in the largest global cohort of cryoablated patients prospectively studied within a single registry.

METHODS

The Cryo AF Global Registry is a prospective, multi-center registry. Patients with paroxysmal AF (PAF) or persistent AF (PsAF) were treated with the cryoballoon catheter according to routine practices at 93 sites across 36 countries. Primary efficacy endpoints included freedom from AF and freedom from AF/atrial flutter (AFL)/atrial tachycardia (AT) ≥30 seconds. The primary safety endpoint was serious device- or procedure-related adverse events over 12 month follow-up.

RESULTS

During this evaluation window, 2922 subjects completed an index cryoballoon procedure, and 1440 completed 12 month follow-up. The cohort was 61 ± 12 years of age, 36.3% female, and 78.7% PAF. Serious device- and procedure-related adverse event rates were 1.5% and 3.4%, respectively. Freedom from AF/AFL/AT after the 90 day blanking period was 86.4% (95% CI: 84.3%-88.3%) in patients with PAF and 70.9% (95% CI: 64.6%-76.4%) in patients with PsAF. Freedom from AF/AFL/AT in first-line PAF and PsAF was 90.0% (95% CI: 86.4%-92.7%) and 72.9% (95% CI: 58.6%-83.0%) at 12 months, respectively.

CONCLUSIONS

The Cryo Global AF Registry is the largest evaluation to demonstrate cryoablation is an efficient, safe, and effective treatment for patients with AF worldwide. Cryoablation was commonly used to treat patients prior to an AAD failure and may facilitate earlier therapy for patients on the AF disease continuum.

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

AIMS

Cryoballoon pulmonary vein isolation (PVI) is a safe and effective treatment for atrial fibrillation (AF). Current limitations include incomplete vein occlusion due to balloon rigidity and inconsistent electrogram recording, which impairs identification of isolation. We aimed to evaluate the acute safety and performance of a novel cryoballoon system.

METHODS AND RESULTS

The system includes a steerable sheath, mapping catheter, and a balloon that maintains uniform inflation pressure and size following initiation of ablation. Protocol-directed cryoablation was delivered for 180 s for isolation documented in ≤60 s, otherwise freeze duration was 240 s. Primary endpoints were acute safety and vein isolation. Pulmonary vein isolation was confirmed at ≥30 min post-isolation. Data were compared across vein locations. Thirty patients with paroxysmal AF were enrolled at two centres and underwent PVI. Pulmonary vein isolation was achieved with cryoablation only in 100% of veins (120/120). Nadir temperature was -53.1 ± 5.3°C. The number of applications to achieve PVI was 1.4 ± 0.4 per vein. Of the 120 veins, 89 were isolated with a single cryothermal application (10/30 patients required only 4 total cryoablations). There were no procedural- or device-related serious adverse events at 30 days post-procedure. A subset (24/30) of patients was followed for 1-year and 71% (17/24) remained free of atrial arrhythmias. Six patients with arrhythmia recurrence were remapped and three had durable PVI for all four veins.

CONCLUSION

In this first human experience, the novel cryoballoon platform was safe, efficacious, and demonstrated a high proportion of successful single ablation isolation.

A second cryoballoon system-New and improved?

Generations of cryoballoon transformed the atrial fibrillation ablation landscape. New advancements continue to make cryoballoon more successful and safer treatment. A new cryoballoon PolaRx from Boston Scientific has unique features compared to that of the Medtronic Arctic Front Advance system. Comparison of the two available cryoballoons will require ongoing larger trial and clinical experience.

The efficacy and safety of cryoballoon catheter ablation in patients with paroxysmal atrial fibrillation

BACKGROUND

Electrical isolation of pulmonary vein ostia is an established therapy for paroxysmal atrial fibrillation.

AIMS

The purpose of this study is to evaluate the long-term efficacy and safety of cryoballoon catheter ablation in paroxysmal atrial fibrillation with normal anatomy of the left atrium.

METHODS

Two hundred fifteen consecutive patients were included in the study (from November 2014 to November 2016). All the patients had symptoms of paroxysmal atrial fibrillation resistant to antiarrhythmic drugs and underwent pulmonary vein cryoisolation using second-generation cryoballoons. Standard "single-shot" cryoballoon exposures were used alternately for each of the four pulmonary veins. The endpoint of the ablation procedure was the electrical isolation of each pulmonary vein.

RESULTS

Sixty-nine patients had stable atrial fibrillation recurrences and left atrial flutter with 30 of 69 patients having atrial fibrillation paroxysms during the first year after primary ablation. Repeated ablation was performed within 6-12 months after the first ablation. In 39 of 69 cases, arrhythmia recurrences were registered during the second and third year after the first ablation. These patients underwent repeated ablation within 12-36 months after the first ablation. In 98% of the patients, no disease progression with a transition to a persistent form of atrial fibrillation was observed. During the mean 5-year follow-up period, no disease progression with the transition to persistent forms of atrial fibrillation was observed.

CONCLUSIONS

It was concluded that in patients with paroxysmal atrial fibrillation, with normal left atrium anatomy and no risk factors, it can be controlled with single pulmonary vein isolation without additional atrial substrate modification.

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.

Same-day discharge after cryoballoon ablation of atrial fibrillation: A multicenter experience

BACKGROUND

It is common practice to observe patients during an overnight stay (ONS) following a catheter ablation procedure for the treatment of atrial fibrillation (AF).

OBJECTIVES

To investigate the safety and economic impact of a same-day discharge (SDD) protocol after cryoballoon ablation for treatment of AF in high-volume, geographically diverse US hospitals.

METHODS

We retrospectively reviewed 2374 consecutive patients (1119 SDD and 1180 ONS) who underwent cryoballoon ablation for AF at three US centers. Baseline characteristics, acute procedure-related complications, and longer-term evaluations of safety were recorded during routine clinical follow-up. The mean cost of an ONS was used in a one-way sensitivity analysis to evaluate yearly cost savings as a function of the percentage of SDD cases per year.

RESULTS

The SDD and ONS cohorts were predominately male (69% vs. 67%; p = .3), but SDD patients were younger (64 ± 11 vs. 66 ± 10; p < .0001) with lower body mass index (30 ± 6 vs. 31 ± 61; p < .0001) and CHA₂ DS₂ -VASc scores (1.4 ± 1.0 vs. 2.2 ± 1.4; p < .0002). There was no difference between SDD and ONS in the 30-day total complication rate (n = 15 [1.26%] versus n = 24 [2.03%]; p = .136, respectively). The most common complication was hematoma in both the SDD (n = 8; 0.67%) and ONS (n = 11; 0.93%) cohorts. Sensitivity analysis demonstrated that when 50% of every 100 patients treated were discharged the same day, hospital cost savings ranged from $45 825 to $83 813 per year across US hospitals.

CONCLUSIONS

SDD following cryoballoon ablation for AF appears to be safe and is associated with cost savings across different US hospitals.

Catheter ablation for atrial fibrillation in a low-volume center using contemporary technology

•

There has been significant heterogeneity in the definition of what constitutes as low volume operator /center for AF ablation.

•

Current literature suggests lower success rates but higher complications rates in low-volume centers.

•

First AF catheter ablation in a low-volume center has comparable safety and efficacy outcomes to high-volume centers using contemporary ablation technologies.

Background

Catheter ablation is increasingly being performed worldwide for atrial fibrillation (AF). However, there are concerns of lower success rates and higher complications of AF ablations performed in low-volume centers. Thus, we sought to evaluate the safety and efficacy of AF catheter ablation in a low-volume center using contemporary technologies.

Methods and results

71 consecutive patients (50 paroxysmal AF [pAF] vs 21 persistent AF) who underwent first catheter ablation were studied. Primary outcome was AF recurrence rate. Secondary outcomes included periprocedural complications, hospitalization for symptomatic tachy-arrhythmias post-ablation and number of repeat ablations. Mean age of our cohort was 59.1 ± 9.7 years, of which 56 (78.9%) were males. 1-year AF recurrence was 19.5% in pAF and 23.8% in persistent AF (p = 0.694). Ablation in persistent AF group required longer procedural (197.76 ± 48.60 min [pAF] vs 238.67 ± 70.50 min [persistent AF], p = 0.006) and ablation duration (35.08 ± 15.84 min [pAF] vs 52.65 ± 28.46 min [persistent AF], p = 0.001). There were no significant differences in secondary outcomes. Major periprocedural complication rate was 2.8%.

Subset analysis on (i) cryoablation vs radiofrequency, (ii) Ensite vs CARTO navigational system and (iii) circular vs high density mapping catheter did not yield significant differences in primary or secondary outcomes.

Conclusions

The AF ablation complication and recurrence free rates in both paroxysmal and persistent AF at one year were comparable to high-volume centers. Long-term follow up is needed. In addition, first AF catheter ablation in a low-volume center is realistic with comparable efficacy and safety outcomes to high-volume centers using contemporary ablation technologies.

Localization of Residual Conduction Gaps After Wide Antral Circumferential Ablation of Pulmonary Veins

Ablation of atrial fibrillation (AF) is the cornerstone therapy for patients with symptomatic AF resistant to anti-arrhythmic drugs or as first-line therapy, and is based on permanent pulmonary vein (PV) isolation. The presence of a conduction gap in a wide antral circumferential ablation lesion around PVs is often sufficient to transform an initially successful ablation into a procedural failure, thus necessitating a redo intervention. The strategy during a redo procedure is based on the detection and ablation of the reconnection gap. Finding gaps is often simple, but also sometimes challenging, because gaps may be difficult to detect, resulting in unnecessary radiofrequency delivery. The present review aimed to describe the various techniques published thus far to detect residual reconnections along the encircling ablation lines around PVs, to help electrophysiologists to detect and ablate reconnection gaps.

Ablation of atrial fibrillation using the fourth-generation cryoballoon Arctic Front Advance PRO

The cryoballoon (CB) is a popular ablation technology used for pulmonary vein isolation. The fourth-generation CB, Arctic Front Advance PRO features a 40% shorter distal tip but retains the internal design from its second-generation predecessor. The Arctic Front Advance PRO and the second-generation CB demonstrated similar thermodynamic characteristics in a computational model. Several observational and retrospective studies established the acute safety and efficacy of the Arctic Front Advance PRO. Real-time electrical isolation was observed in 75-85% of pulmonary veins targeted with the Arctic Front Advance PRO resulting in shorter fluoroscopy and procedure times.

The Cryoballoon vs Irrigated Radiofrequency Catheter Ablation (CIRCA-DOSE) Study Results in Context

The Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double Short vs Standard Exposure Duration (CIRCA-DOSE) study was a multicentre, randomised, single-blinded trial that compared contact-force radiofrequency ablation and two different regimens of cryoballoon ablation. All patients received an implantable cardiac monitor for the purpose of continuous rhythm monitoring, with all arrhythmia events undergoing independent adjudication by a committee blinded to treatment allocation. The study demonstrated there were no significant differences between contact-force radiofrequency ablation and cryoballoon ablation with respect to recurrence of any atrial tachyarrhythmia, symptomatic atrial tachyarrhythmia, asymptomatic AF, symptomatic AF or AF burden. While the results of the CIRCA-DOSE study are reviewed here, this article focuses on considerations around the design of the study and places the observed outcomes in context.

Risk of atrioesophageal fistula with cryoballoon ablation of atrial fibrillation

Background

Although there are considerable data on the safety of cryoablation, data on the rare but severe complication of atrioesophageal fistula (AEF) following cryoballoon ablation are limited.

Objective

To report the global, user-reported incidence of AEF associated with cryoballoon ablation for the treatment of atrial fibrillation using Medtronic's complaint database.

Methods

User-reported cryoballoon ablation complications occurring between July 1, 2009, and March 31, 2019, were reviewed to identify cases of AEF. A global event rate of AEF was calculated by dividing the event count by total catheter utilization over the same period. Data on symptoms and patient sequalae were reported as available.

Results

More than 500,000 Arctic Front cryoballoon catheters (Arctic Front, Arctic Front Advance, Arctic Front Advance ST, and Arctic Front Advance Pro; Medtronic, Inc) were distributed globally during the 9.75-year study period. During this time, 18 confirmed AEF, 1 suspected AEF, and 1 pericardial esophageal fistula were identified; therefore, global incidence of AEF associated with the Arctic Front family of ablation catheters was 0.00396%. Patients most commonly presented with fever (88.2%), and initial symptoms were reported a median of 21 (interquartile range: 4-30) days after the ablation. Although rare, the development of an AEF resulted in death in 68.8% (11/16) of patients with known outcomes.

Conclusions

AEF is a possible but rare complication of cryoballoon ablation with a reported frequency of 1 in every 25,000 patients treated. Awareness of the prevalence and manifestation of AEF associated with cryoballoon ablation is critical for early identification and treatment of this complication.

Long-term outcomes after second-generation cryoballoon ablation of paroxysmal atrial fibrillation - Feasibility of a single short freeze strategy without bonus applications

BACKGROUND

A paucity of data exists about long-term outcomes after second-generation cryoballoon ablation (2nd-CBA), and the feasibility of short freeze strategies remains under debate. We assessed the long-term follow-up outcomes.

METHODS

This study included 186 paroxysmal atrial fibrillation (PAF) patients (62 ± 11 years, 136 men) who underwent 2nd-CBAs with a 28-mm balloon and single 3-min freeze strategy without bonus applications. Fourteen-day consecutive monitoring was performed to detect early AF recurrences (ERAFs).

RESULTS

Overall, 713/736(96.9%) PVs were isolated with CBs. The total number of applications/patient was 5.3 ± 1.5. The total procedure and fluoroscopic times were 79.9 ± 28.1 and 24.4 ± 14.2 min. Asymptomatic right phrenic nerve injury occurred in 11 patients, however, all recovered during the follow-up. A total of 76(41.7%) patients experienced ERAFs. During a median 45.0 [30.0-51.0] month follow-up, the single procedure AF freedom was 76.1, 73.5, 70.5, and 63.7% at 1, 2, 3, and 4 years, respectively. At a median of 7.0 [4.0-12.0] months after the initial procedure, 35 (18.8%) patients underwent second procedures, and 106/137 (77.4%) PVs were still isolated. The multiple procedure AF freedom was 91.7, 89.3, 86.8, and 81.3% at 1, 2, 3, and 4 years, respectively. A Cox's proportional hazards model determined that the presence of ERAF was associated with a greater risk of recurrence after the last procedure (Hazard ratio = 2.830; 95% confidence interval = 1.173-6.833; p = 0.021). The percentage of continuation of anticoagulation therapy after the initial procedure was 33.1, 23.5, 21.7, and 21.7% at 1, 2, 3, and 4 years, respectively.

CONCLUSIONS

Our long-term follow-up data demonstrated the feasibility of a single short freeze strategy in PAF patients.

Cryoablation for atrial fibrillation

Cryoballoon ablation for the treatment of atrial fibrillation has established itself as an effective and efficient modality for achieving pulmonary vein isolation. Over the past 13 years more than 100,000 Cryoballoon ablation procedures have been performed with the first to fourth generation cryoballoons. Over that time there have been significant advances in our understanding regarding the optimal procedural techniques. The purpose of this "topic in review" is to focus on the practical aspects of performing a Cryoballoon ablation procedure, within the context of the contemporary literature. Specifically there is a focus on how contemporary studies can inform clinical decision making and ensure operators are able to perform a safe and effective procedure.

The mechanisms of recurrent atrial arrhythmias after second-generation cryoballoon ablation

BACKGROUND

In patients with paroxysmal atrial fibrillation (PAF), 10%-15% of patients require repeat procedures after second-generation cryoballoon pulmonary vein isolation (CB-PVI). We sought to explore the mechanisms of recurrences after cryoballoon ablation.

METHODS

The data of 122 PAF patients who underwent second procedures for recurrent arrhythmias 7.0 (4.0-12.0) months after the CB-PVI were analyzed. During second procedures, non-PV AF foci were explored with isoproterenol, adenosine, and repetitive cardioversions.

RESULTS

In total, 378/487 (77.6%) PVs remained isolated, and reconnections were not observed in any PVs in 59 (48.4%) patients. PV reconnections were associated with recurrences in 38 (31.1%) patients, of whom 33 (86.8%) had reconnections of at least 1 upper PV. In 6 (4.9%) patients, non-PV AF foci were identified in the upper PV antra where cryoballoons cannot isolate but within the circumferential radiofrequency PVI line. Non-PV AF foci were identified in the superior vena cava, right atrial body, left atrial body, and atrial septum in 28 (23.0%), 18 (14.7%), 4 (3.3%), and 5 (4.1%) patients, respectively. Twelve (9.8%) patients had multiple non-PV AF foci. Four (3.3%), 3 (2.4%), and 8 (6.5%) patients underwent second procedures for atrioventricular nodal reentrant tachycardia, atrial flutter, and atrial tachycardias. During 16.0 (8.0-24.0) months of follow-up, freedom from any atrial arrhythmia at 1 year and 2 years after the second procedure was 79.2% and 60.6%. Nineteen (15.5%) patients had antiarrhythmic drug therapy at the last follow-up.

CONCLUSIONS

Our study suggested that improvement in the upper PV PVI durability, eliminating arrhythmogenic superior vena cavae and coexisting atrial arrhythmias, and bonus cryoballoon applications at PV antra might improve the single procedure outcome in cryoballoon ablation.

Novel three-dimensional imaging approach for cryoballoon navigation and confirmation of pulmonary vein occlusion

BACKGROUND

Cryoballoon apposition is crucial for durable pulmonary vein isolation (PVI) in atrial fibrillation, yet the balloon is difficult to visualize by conventional mapping systems, and pulmonary venography may miss small or out-of-plane leaks. We report a novel imaging system that offers real-time 3D navigation of the cryoballoon within atrial anatomy that may circumvent these issues.

METHODS AND RESULTS

A novel overlay guidance system (OGS) registers already-acquired segmented atrial cardiac tomography (CT) with fluoroscopy, enabling real-time visualization of the cryoballoon within tomographic left atrial imaging during PVI. Phantom experiments in a patient-specific 3D printed left atrium showed feasibility for confirming PV apposition and leaks. We applied OGS prospectively to 68 PVs during PVI in 17 patients. The cryoballoon was successfully reconstructed in all cases, and its apposition was compared to concurrent PV venography. The OGS uncovered leaks undetected by venography in nine veins (eight cases), which enabled repositioning, confirming apposition in remaining 68 veins. Concordance of OGS to venography was 83.8% (χ² , P < .01) CONCLUSIONS: We report a new system for real-time imaging of cryoballoon catheters to ensure PV apposition within the tomography of the left atrium. While providing high concordance with other imaging modalities for confirming balloon apposition or leak, the system also identified leaks missed by venography. Future studies should determine if this tool can provide a new reference for cryoballoon positioning.

Cryoballoon Ablation for Patients With Paroxysmal Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice and induces cardiac dysfunction and stroke. The development of AF requires a trigger and also an electroanatomic substrate capable of both initiating and perpetuating AF. In the past decade, ectopic beats originating from the pulmonary veins (PV) have been identified as a source of paroxysmal AF. Thus, strategies that target the PV, including the PV antrum, are the cornerstone of most AF ablation procedures. Recently, alternative technologies to radiofrequency catheter ablation for paroxysmal AF such as balloon ablation modalities have been developed. The purpose of this review is to discuss cryoballoon ablation for paroxysmal AF.

Predictors of cardiac neuromodulation achieved by cryoballoon ablation performed in patients with atrial fibrillation who were in sinus rhythm before the ablation

BACKGROUND

The impact of pulmonary vein isolation (PVI) performed with cryoballoon (CB) on the intrinsic cardiac autonomic nervous system (ICANS) remains unclear.

OBJECTIVE

The purpose of this study was to evaluate the predictors and the clinical meaning of cardiac neuromodulation achieved by CB-ablation as assessed by sinus heart rate (HR) response after the procedure.

METHODS

Patients who underwent CB-ablation for drug-resistant atrial fibrillation (AF) from January 2014 to October 2018 were included. Twelve‑leads rest ECG was taken both before and after the procedure. After discharge, patients were scheduled for follow-up visits at 1, 3, 6, and 12 months and 24 h Holter recordings were obtained at each follow-up visit. All documented AF episodes of >30 s were considered as recurrence.

RESULTS

Four-hundred seventy-two patients (62.3% male, age 56.7 ± 13.6 years, 97.2% paroxysmal AF) were included. Mean HR before the procedure was 60.17 ± 10.4 bpm, while the morning after the procedure mean HR was 75.48 ± 12.0 bpm. Age at enrollment (R = -0.26; p < 0.001), baseline HR before the CB-A (R = -0.32; p < 0.001), nadir temperature in each right pulmonary vein (R = -0.11, p = 0.022; R = -0.16; p = 0.001) were significantly associated with the ∆HR. At 2-year follow-up, freedom from recurrences was 83.1% for the patients with HR increase ≥15 bpm after CB-A and 66.3% in patients with HR increase ˂15 bpm (p = 0.021).

CONCLUSION

Sinus HR increase is a frequent phenomenon after CB-A, that can be predicted by both clinical and procedural factors and that correlates with better outcome after cryo-PVI.

Pulmonary veins anatomical determinants of cooling kinetics during second-generation cryoballoon ablation

AIM

The aim of the study was to investigate the role of anatomical characteristics of the pulmonary veins (PVs) determining cooling kinetics during second-generation cryoballoon ablation (CbA).

METHODS AND RESULTS

we enrolled all consecutive patients who underwent CbA for symptomatic atrial fibrillation in our center from January 2019 to March 2019. All patients had complete computed tomography scans of the heart before the ablation. Anatomical characteristics were tested for prediction of a nadir temperature (NT) ≤ -48°C. Significant differences were noted among PV max diameter (20.8 ± 2.8 vs 18.5 ± 2.5 mm; P < .001); PV minimum diameter (15.2 ± 3.0 vs 13.0 ± 3.1 mm; P < .001); PV area (268.1 ± 71.9 vs 206.2 ± 58.7 mm² ; P < .001); PV ovality (1.4 ± 0.3 vs 1.5 ± 0.3; P = .005); and PV trunk length (27.4 ± 7.4 vs 21.3 ± 6.5 mm; P < .001). A scoring system was created by assigning one point each ranging from 0 (best anatomical combination) to 5. In the group with a score of 0, 94.0% of the CbA could reach a NT ≤ -48°C whereas with a score of 5, only 29.0% (P < .001). Left superior pulmonary vein with short trunk length and acute angle of PV branch was significantly associated with warmer NT (11.8% satisfactory CbA; P = .003). Regarding right inferior pulmonary vein, trunk length (P = .004), maximum diameter (P = .044), and transverse angle (P = .008) were independently associated with good NT.

CONCLUSION

Anatomical PV features are associated with cooling kinetics and an anatomical score could predict lower NT during second-generation CbA. Specific characteristics were identified for inferior PV. Although heart imaging is not mandatory prior CbA, it can be a useful tool to predict cooling kinetics.