Cryoballoon Versus Open Irrigated Radiofrequency Ablation in Patients With Paroxysmal Atrial Fibrillation: The Prospective, Randomized, Controlled, Noninferiority FreezeAF Study

Acute Procedural Complications of Cryoballoon Ablation: A Comprehensive Review

Catheter ablation is increasingly performed for treatment of atrial fibrillation (AF). Balloon based procedures have been developed aiming at safer, easier and more effective treatment as compared to point to point ablation. In the present review article, we aimed to discuss acute procedural complications of cryoballoon ablation.

Prevention of serious air embolism during cryoballoon ablation; risk assessment of air intrusion into the sheath by catheter selection and change in intrathoracic pressure: An ex vivo study

INTRODUCTION

One cause of cerebral infarction during cryoballoon ablation is the entry of air into a sheath due to the use of inappropriate catheters. It is known that the left atrial pressure of patients with obstructive sleep apnea syndrome can be negative. However, the effects of catheter selection and negative pressure changes in the sheath on air intrusion are not yet well understood. The aim of this study was to evaluate how catheter selection and negative pressure changes affect air intrusion and to perform countermeasures for air intrusion.

METHODS AND RESULTS

This experiment used siphon principle to create negative pressure in the sheath. Noncryoablation catheters (not designed exclusively for cryoballoon ablation) and cryoballoon catheters were investigated. Catheters were inserted into the sheath and then removed. Thereafter, the amount of air in the sheath was measured. For catheters producing significantly larger amounts of air intrusion, the catheters were inserted via a long sheath in the sheath (sheath-in-sheath technique) and the same procedures were repeated. We found that the amount of air intrusion through most of the noncryoablation catheters was significantly larger than that through cryoablation catheters. An increase in the magnitude of negative pressure in the sheath resulted in a proportional increase in air intrusion, but the sheath-in-sheath technique significantly reduced air intrusion.

CONCLUSION

The amount of air intrusion increased when using catheters with complicated tip shapes and thin outer diameters and when the magnitude of negative pressure in the sheath increased. The sheath-in-sheath technique may be an effective countermeasure.

Thermodynamic properties of atrial fibrillation cryoablation: a model-based approach to improve knowledge on energy delivery

The objective of this study is to describe a suitable model of atrial fibrillation cryoablation thermodynamic properties. Three different thermal loads were applied to a cylindrical copper element simulating the cryoprobe, thermally coupled with a Peltier stack producing the freezing effect, and in contact with a bovine liver sample. Thermal events occurring inside the samples were measured using mirror image technique. Heat subtracted flux during ice formation and minimum temperature measured at probe-tissue interface were, respectively, 1.33 W cm^-2 and -27.8°C for Sample#0, 1.88 W cm^-2 and -35.6°C for Sample#1 and 1.82 W cm^-2 and 1.44 W cm^-2 before and after the ice trigger, respectively, and -29.3°C for Sample#2. Ice trigger temperature was around -8.5°C for Sample#0 and Sample#2, and -10.4°C for Sample#1. In all the investigated samples, ice front penetration was proportional to the square root of time and its velocity depended on the heat flux subtracted. The fraction of the useful energy spent for ice formation was less than 60% for Sample#0, and about 80% for Sample#1 and for Sample#2, before the reduction of the removed heat flux. Freezing time exceeding a cut-off, according to the heat subtracted flux, does not improve the procedure effectiveness and is detrimental to the surrounding tissues.

Second Generation Cryoballoon vs. Radiofrequency Ablation in Paroxysmal Atrial Fibrillation: Outcomes Beyond One-Year Follow-up

Aims

Pulmonary vein isolation (PVI) can be accomplished using radiofrequency (RF) or second generation cryoballoon (CB2). We aimed to compare the freedom from very late recurrence (VLR) defined as recurrence beyond one year in patients who were AF-free during the first post-procedural year after PVI using CB2 or RF.

Methods

Consecutive patients who underwent PVI by RF or CB2 ablation between August 2014 and December 2015 were included. The primary endpoint was the occurrence of VLR in follow-up after 12 months. Patients who experienced recurrence between the first 3 to 12 months after PVI and those who did not complete 15-month follow-up time were excluded.

Results

139 patients were included: 68 underwent PVI by CB2 and 71 using RF. The global VLR rate was of 22.15%. The freedom from VLR beyond 12-month follow-up was of 84.5% (57 patients) for the CB2 group vs. 71% (50 patients) in the RF group (p=0.037). 15 patients underwent re-ablation (11 of the RF group and 4 of the CB2 group): all of the patients who had undergone PVI by RF in the index procedure were found to have vein reconnection, whereas none of the CB2 group had reconnected veins (3 cavotricuspid isthmus and 1 mitral isthmus).

Conclusion

In patients free of recurrence during the first post-procedural year after pulmonary vein isolation for the treatment of paroxysmal atrial fibrillation: second generation cryoballoon ablation showed a significantly lower very late recurrence rate compared to radiofrequency ablation.

Condensed abstract

The present study evaluates the freedom from very late recurrence (VLR), defined as recurrence in patients who were arrhythmia-free during the first post-procedural year after pulmonary vein isolation using second generation cryoballoon (CB2) or radiofrequency (RF). CB2 ablation had a lower VLR rate compared to RF.

Sex-specific efficacy and safety of cryoballoon versus radiofrequency ablation for atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Atrial fibrillation (AF) is a growing healthcare burden, for which pulmonary vein isolation (PVI) using cryoballoon (CB) or radiofrequency (RF) represent attractive therapies. Women are at higher risk of recurrence after AF ablation and present a specific complications profile. Therefore, a systematic catheter-specific assessment of pulmonary vein isolation is urgently needed in women.

OBJECTIVE

Systematically assessing the sex-specific efficacy/safety of CB vs RF ablation.

METHODS

We performed a structured database search of the scientific literature for randomized controlled trials (RCTs) and observational prospective studies (OPS) comparing CB and RF ablation efficacy at 1 year. We investigated the reporting of sex-specific analyses and assessed the comparative sex-specific efficacy, safety and procedural characteristics of CB vs RF using random-effect meta-regression accounting for the proportion of enrolled women.

RESULTS

Twenty-three studies were included (18 OPS and 5 RCTs) for a total of 13 509 patients. Sex-specific outcomes by ablation device were reported in two and sex-specific regression in four studies, none of which took the ablation device into account. Meta-regression accounting for the proportion of enrolled women showed no significant difference in outcomes between RF or CB.

CONCLUSION

The sex-specific reporting in trials comparing CB to RF is extremely low. A quantitative meta-regression using the percentage of enrolled women as sex-specific indicator did not show any difference between CB and RF but acknowledging the low percentage of enrolled women and the lack of sex-specific data, further research including patient-level data is urgently needed to draw more definitive conclusions.

Cryoballoon Ablation for the Treatment of Atrial Fibrillation: A Meta-analysis

BACKGROUND

Ablation therapy is the treatment of choice in antiarrhythmic drugrefractory atrial fibrillation (AF). It is performed by either cryoballoon ablation (CBA) or radiofrequency ablation. CBA is gaining popularity due to simplicity with similar efficacy and complication rate compared with RFA. In this meta-analysis, we compare the recurrence rate of AF and the complications from CBA versus RFA for the treatment of AF.

METHODS

We systematically searched PubMed for the articles that compared the outcome of interest. The primary outcome was to compare the recurrence rate of AF between CBA and RFA. We also included subgroup analysis with complications of pericardial effusion, phrenic nerve palsy and cerebral microemboli following ablation therapy.

RESULTS

A total of 24 studies with 3527 patients met our predefined inclusion criteria. Recurrence of AF after CBA or RFA was similar in both groups (RR: 0.84; 95% CI: 0.65, 1.07; I2=48%, Cochrane p=0.16). In subgroup analysis, heterogeneity was less in paroxysmal AF (I2=0%, Cochrane p=0.46) compared to mixed AF (I2=72%, Cochrane p=0.003). Procedure and fluoroscopy time was less by 26.37 and 5.94 minutes respectively in CBA compared to RFA. Complications, pericardial effusion, and silent cerebral microemboli, were not different between the two groups, however, phrenic nerve palsy was exclusively present only in CBA group.

CONCLUSION

This study confirms that the effectiveness of CBA is similar to RFA in the treatment of AF with the added advantages of shorter procedure and fluoroscopy times.

Clinical significance of early recurrence of atrial fibrillation after cryoballoon vs. radiofrequency ablation-A propensity score matched analysis

Objectives

One of the mechanisms of early recurrence of atrial fibrillation (ERAF) after AF ablation is considered to be the inflammatory reaction of the atrial tissue. The aim of this study is to compare the clinical significance of ERAF at each stage for true AF recurrence between cryoballoon (CB) and radiofrequency (RF) ablation.

Methods

Among 798 paroxysmal AF patients who underwent an initial ablation, 460 patients (CB, n = 230; RF, n = 230) were selected by propensity score matching. Very ERAF (VERAF), ERAF-1M, ERAF-3M and true AF recurrence were defined as AF recurrence at 0–2, 3–30, 31–90 days and more than 90 days after the procedure, respectively.

Results

The patient characteristics of the two groups were similar. ERAF was observed 21% and 27% in the CB and RF groups, respectively. In both the CB and RF group, VERAF, ERAF-1M and ERAF-3M were more frequently observed in patients with true AF recurrence than in those without. In a multivariable analysis, ERAF-1M and ERAF-3M were found to be independent predictors of true AF recurrence in both the CB (P = 0.04 and P<0.001, respectively) and RF groups (P = 0.02 and P = 0.001, respectively). However, while VERAF was associated with true AF recurrence after RF ablation (P = 0.03), it was not associated with true AF recurrence after CB ablation (P = 0.19).

Conclusion

The relationship between ERAF and true AF recurrence differed between the RF and CB ablation groups. While VERAF was associated with true AF recurrence after RF ablation, it was not a predictor of true AF recurrence after CB ablation.

Long-term outcomes of pulmonary vein isolation using second-generation cryoballoon during atrial fibrillation ablation

BACKGROUND

Currently available second-generation cryoballoon (CB2) is accepted as an effective and safe tool for pulmonary vein isolation (PVI). Although much more data exist about 1-year outcomes of CB2 ablation, data on long-term outcomes are scarce.

OBJECTIVE

We aimed to assess the long-term outcomes of PVI using CB2 in a large-scale symptomatic atrial fibrillation (AF) population at our tertiary referral center.

METHODS

In this nonrandomized prospective observational study, a total of 486 patients with paroxysmal (71%) or persistent (29%) AF who underwent index PVI using CB2 at our hospital between January 2013 and June 2017 were enrolled. Atrial tachyarrhythmia (ATa)-free survival was defined as the absence of AF, atrial flutter, or atrial tachycardia recurrence ≥30 s following a 3 months blanking period. Predictors of recurrence were evaluated by univariate and multivariate Cox proportional hazards regression models.

RESULTS

Acute procedural success rate was 99.8% (1898/1902 PVs). Mean procedural and fluoroscopy time were 64.9 ± 9.2 and 12.1 ± 2.6, respectively. At median 39 (interquartile range: 26-56) months follow-up, ATa-free survival was 78.6% after a single procedure (280/345 [81.2%] for paroxysmal AF vs. 102/141 [72.3%] for persistent AF, P = .019) and 84.4% after a mean 1.48 ± 0.42 ablations. Cox regression analysis showed that left atrium diameter, duration of AF history, and early ATa recurrence were found as the independent predictors of late recurrence. Phrenic nerve palsy was observed in 17 (3.5%) patients.

CONCLUSIONS

CB2-based PVI is effective to maintain sinus rhythm in a significant proportion of paroxysmal and persistent AF patients with an acceptable complication rate at long-term follow-up.

Predictors of freedom from atrial arrhythmia recurrence after cryoballoon ablation for persistent atrial fibrillation: A multicenter study

AIMS

We sought to assess (1) clinical outcomes of second-generation cryoballoon (CB) ablation for persistent atrial fibrillation (AF), and (2) the association of baseline and procedural covariates with atrial arrhythmia recurrence (AAR) after ablation.

METHODS

A total of 135 patients (63 ± 11 years, 96 men [71%]) with persistent AF underwent CB ablation at three experienced electrophysiology centers. Freedom from AAR was estimated with the Kaplan-Meier method. A Cox proportional-hazards model was used to estimate the effects of baseline and procedural covariates on the likelihood of AAR.

RESULTS

Freedom from AAR at 6, 12, and 18 months was estimated at 91% (95% confidence interval [CI] 86%-96%), 75% (95% CI, 67%-83%), and 53% (95% CI, 43%-65%), respectively. The presence of an implantable cardiac device (Hazard ratio [HR] 3.09; 95% CI, 1.37-7.00; P = .007), a left atrial (LA) diameter > 50 mm (HR 1.69; 95% CI, 1.02-2.79; P = .043), and absence of antiarrhythmic drug (AAD) therapy before the ablation procedure (HR 3.12; 95% CI, 1.72-5.64; P < .001) were associated with AAR. A trend toward an increased risk of AAR was revealed for women (HR 1.73; 95% CI, 0.96-3.11; P = .069).

CONCLUSIONS

CB ablation for persistent AF resulted in freedom from AAR about that reported for RF ablation. The presence of an implantable cardiac device, LA size, and absence of AAD therapy at baseline were associated with the risk of AAR.

Cryoballoon ablation results and complications in mid-term follow-up of patients with atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common cardiac arrhythmia, and its prevalence increases with advancing age. Pulmonary vein isolation is a standard approach in drug refractory paroxysmal AF which could be performed by cryoballoon ablation (CBA). We tried to evaluate its efficacy and safety in Iranian patients with AF.

METHODS

From 2015 to 2017, 97 patients with paroxysmal and persistent AF were enrolled in our observational historical cohort study. They were visited 1 and 6 months post-procedure in order to assess the efficacy (recurrence) and safety. Recurrence was defined as 30 seconds of arrhythmia on their 48-hours Holter monitoring.

RESULTS

Ninety-seven patients enrolled in the study, 64 (66.0%) of them were men, and their mean age was 55 ± 12 years. Hypertension was reported in 41 patients (42.3%), as the most common cardiac risk factor. 71 patients (73.2%) patients with paroxysmal AF and 15 patients (15.5%) with persistent AF underwent the procedure. After 6 months, recurrence was documented in only 17 patients (17.5%), and 82.5% of the patients were free from the recurrence. Post-procedural complication was detected only in 3 patients (3.1%).

CONCLUSION

In our study, the mid-term success and safety of CBA in patients with paroxysmal AF was showed. CBA is a safe and effective method in paroxysmal AF, and even in some cases with persistent AF.

Robotic navigation shows superior improvement in efficiency for atrial fibrillation ablation

Background

Because of the expanding atrial fibrillation (AF) burden, AF catheter ablation (CA) techniques have to become more efficient. Efficient AF CA procedures are characterized by successful pulmonary vein isolation (PVI) within reasonable procedure time. Currently there are many PVI techniques available and all show substantial improvements over time. However, the magnitude of improvement in procedural efficiency has not yet been compared between different techniques. The aim of this study was to compare efficiency improvement between manually (MAN) guided, cryoballoon (CB) and remote magnetic navigation (RMN) guided PVI.

Methods

A total of 221 patients were included in this retrospective study. Procedural parameters of 115 patients treated with first-generation PVI techniques (MAN-1, CB-1, RMN-1) performed in 2010, were compared to 106 patients who were treated with the latest, second generation techniques (MAN-2, CB-2, RMN-2). Efficiency was characterized by the following parameters: total ablation time, total procedure time, first pass isolation (FPI) (i.e. successful isolation after the first pulmonary vein (PV) encirclement) and touch-up rates.

Results

Every technique showed significant improvement of procedure times from the first to the second generation (P<0.001). In-between second generation techniques, the procedure times were comparable. The greatest magnitude of procedure time improvement was observed within the RMN groups (∆-180min), which was significantly greater compared to CB (∆-48 min, P<0.001) and MAN (∆-98min, P=0.011) groups. The highest FPI rates were observed in RMN-2 (78% and 74%; left and right PVs respectively), which was significantly higher compared to other techniques (MAN-2: 24% and 24%; CB-2: 50% and 48%; P<0.001).

Conclusions

The highest magnitude of efficiency improvement was detected in RMN guided PVI.

A Cost-Utility Analysis of Cryoballoon Ablation versus Radiofrequency Ablation for Paroxysmal Atrial Fibrillation

Introduction

The objective of this study was to evaluate the cost-effectiveness of the treatment with cryoballoon (CB) compared to the standard treatment with traditional irrigated radiofrequency (RF) ablation for pulmonary vein isolation in patients with paroxysmal atrial fibrillation (pAF) refractory to antiarrhythmic drug therapy.

Methods

A decision tree model was developed to graphically depict the probabilities, utilities and costs of CB compared to RF therapy. Data from a conducted systematic literature review and meta-analysis of only RCTs were used to evaluate clinical outcomes of CB and RF treatments, including success rates after one year, complications and recurrence of atrial fibrillation.

Results

The cost-utility analysis estimated that, CB therapy had £1,747 higher cost, and 0.0114 more quality-adjusted life years (QALYs) compared to standard RF treatment over a one-year time horizon. The incremental cost per QALY of CB ablation compared to RF ablation was estimated to be £152,836/QALY.

Conclusions

Based on current evidence, CB ablation for pulmonary vein isolation in patients with pAF is costeffective compared to RF if decision makers are willing to pay £152,836 or higher for a QALY.

Time-to-isolation-guided cryoballoon ablation reduces oesophageal and mediastinal alterations detected by endoscopic ultrasound: results of the MADE-PVI trial

Aims

Cryoballoon ablation is safe and efficient for achieving pulmonary vein isolation (PVI) in atrial fibrillation. Structural oesophago-mediastinal lesions, which seem to be associated with an increased risk of the lethal complication of an atrio-oesophageal fistula, have been described. MADE-PVI (Mediastino-oesophageal Alterations Detected by Endosonography after PVI) aimed at evaluating safety of cryoballoon PVI in relation to two different freeze protocols. As time-to-isolation-(TTI)-guided protocol has been reported to be as effective as conventional ‘two freeze protocol’, we hypothesized a TTI-guided protocol causes less oesophago-mediastinal lesions.

Methods and results

Seventy consecutive patients were scheduled for cryoballoon (2nd generation) PVI employing either a conventional protocol (n = 35: 2 × 180 s per vein) or a TTI-guided approach (n = 35: TTI + 120 s per vein or 1 × 180 s in case TTI could not be measured). Oesophagogastroduodenoscopy and endoscopic ultrasound, assessing oesophago-mediastinal alterations (e.g. ulceration, oedema) were performed blinded prior and post-ablation. Post-interventional mediastinal oedematous alterations were detected in 70% with a mean diameter of 14 mm (±0.9 mm), while only 15% revealed large mediastinal oedema >20 mm. Oesophageal lesions due to PVI occurred in 5%. Freeze protocols had a distinct impact on oesophago-mediastinal alterations as mean diameter and frequency of large oedema were significantly increased in patients after conventional protocol PVI (17 mm vs. 11 mm; 26% vs. 6%). Furthermore, every oesophageal lesion was detected in patients with conventional protocol (9%). No major complication occurred in either group.

Conclusion

The present prospective study demonstrates a significant impact of freeze protocol on oesophago-mediastinal alterations. A TTI-guided protocol reduces mediastino-oesophageal lesions and may reduce short- and long-term complications of cryoballoon PVI.

Feasibility and safety of cryoballoon ablation for the treatment of atrial fibrillation in patients with congenital heart disease

BACKGROUND

The prevalence of atrial fibrillation (AF) is on the rise in the aging population with congenital heart disease (CHD). A few case series have described the feasibility and early outcomes associated with radiofrequency catheter ablation of AF centered on electrically isolating pulmonary veins (PVs) in patients with CHD. In contrast, cryoballoon ablation has not previously been studied in this patient population despite its theoretical advantages, which include a favorable safety profile and shorter procedural time.

AIM

To assess the safety and feasibility of cryoballoon ablation for AF in an initial cohort of patients with CHD.

METHODS

The study population consisted of consecutive patients with CHD who underwent cryoballoon ablation for AF at the Montreal Heart Institute between December 2012 and June 2017. Procedural complications, acute success, and 1-year freedom from recurrent AF after a single procedure with or without antiarrhythmic drugs were assessed. Procedures were performed under conscious sedation. Left atrial access was obtained via a single transseptal puncture or through an existing atrial septal defect (ASD). Cryoballoon occlusion was assessed by distal injection of 50% diluted contrast into the PV. At least one 240-s cryothermal application was performed when complete PV occlusion was obtained. Following ablation, patients were routinely followed at outpatient visits at 1, 3, 6, and 12 mo, and annually thereafter.

RESULTS

Ten patients with a median age of 57.9 (interquartile range 48.2-61.7 years) and 60% female, met the inclusion criteria and were followed for 2.8 (interquartile range 1.4-4.5) years. Two patients had moderately complex CHD (sinus venosus ASD with partial anomalous pulmonary venous return; aortic coarctation with a persistent left superior vena cava), with the remainder having simple defects. AF was paroxysmal in 8 (80.0%) and persistent in 2 (20.0%) patients. The PV anatomy was normal in 6 (60.0%) patients. Four had left common PV (n = 3) and/or 3 right PV (n = 2). Electrical pulmonary vein isolation (PVI) was acutely successful in all patients. One patient had transient phrenic nerve palsy that recovered during the intervention. No major complications occurred. One year after a single ablation procedure, 6 (60%) patients remained AF-free. One patient with recurrent AF had recovered PV conduction and underwent a second PVI procedure. A second patient underwent ablation of an extra-pulmonary vein trigger for AF.

CONCLUSION

Cryoballoon ablation for AF is feasible and safe in patients with simple and moderate forms of CHD, with an excellent acute success rate and modest 1-year freedom from recurrent AF.

Hybrid Ablation of Ventricular Tachycardia: a Single-Centre Experience

Background

The long-term results of endocardial and percutaneous epicardial catheter ablation of ventricular tachycardia (VT) in patients with structural heart disease are disappointing. Arrhythmia recurrence after ablation and VTs with an epicardial substrate remain a clinical challenge. The purpose of this manuscript is to elaborate on feasibility and potential advantages of a surgical hybrid ablation (i.e., combined endocardial and surgical epicardial ablation) based on our initial experience consisting of five cases.

Methods

Endocardial electro-anatomical voltage and activation maps were created (Carto, Biosense Webster, California, USA), and endocardial radiofrequency (RF) applications were applied at exit sites, low voltage areas and isthmi. Next, after surgical access, epicardial voltage and activation maps were produced in combination with visual assessment of the epicardial substrate. Epicardial low voltage areas, isthmi and exit sites were identified and ablated using RF energy.

Results

After the procedure, VT was non-inducible in 80% of the cases (4/5, in one case no induction was performed). No peri-procedural complications occurred. After a mean follow-up of 18 months, one patient remained in sinus rhythm without, and 2 with use of antiarrhythmic drugs. One patient needed a redo procedure after 21 months, and in one patient the amiodarone dose was raised because of 2 sustained VTs. After this additional treatment, both kept sinus rhythm.

Conclusions

Hybrid VT ablation is a safe and effective patient tailored procedure that comprises the major advantage of combining direct anatomical visualization and enhanced catheter stability with high-density 3D mapping. As a consequence, this procedure should be considered as a valid treatment option in complex VT management.

Pathology Approaches to Determine Safety and Efficacy of Cardiac Ablation Catheters

Cardiac electrophysiology utilizes nonimplantable, catheter-based devices for diagnosis and treatment of arrhythmias as well as electroanatomical mapping of cardiac chambers. Gross pathology and histopathological assessments in preclinical studies play critical roles in determining the safety and efficacy of cardiac ablation systems used to treat tachyarrhythmias. The pathologist must assess ablation sites, adjacent structures and organs, and downstream organs to characterize the effects of the ablation treatment and determine whether adverse local reactions, collateral injury, or downstream thromboembolism are present. Histopathological assessment serves as an adjunct to electroanatomical data in determining efficacy in preclinical studies. Histopathology is the standard in definitively demonstrating transmurality of ablation lesions, which is necessary for complete conduction block, as well as showing the linear or circumferential distribution of a contiguous, transmural ablation lesion necessary for electroanatomical isolation of entire target structures such as pulmonary veins and the cavotricuspid isthmus, which are involved in propagating certain arrhythmias. This article will detail gross and histological methods for the pathology assessment of preclinical studies evaluating the safety and/or efficacy of cardiac ablation catheter systems as well as discuss correlation of pathology data with other supporting evidence for safety and efficacy such as acute, electroanatomical data.

Significant reduction of radiation exposure in cryoballoon-based pulmonary vein isolation

Aims

Procedure times and left atrial dwell times of cryoballoon (CB)-based ablation strategies for atrial fibrillation (AF) are shorter as compared to radiofrequency ablation, yet fluoroscopy times are longer and result in a higher radiation exposure. The objective of this study is to evaluate a modified fluoroscopy protocol aiming at reduction of radiation exposure in CB ablation.

Methods and results

A total of 120 patients with symptomatic AF underwent pulmonary vein isolation (PVI) using the second generation CB and an ablation strategy considering the individual time-to-isolation. The first 60 patients (Group 1) underwent CB-based PVI with conventional fluoroscopy settings. An optimized approach was applied in the following 60 patients (Group 2) by (i) using fluoroscopy instead of filming for verification of pulmonary vein (PV) occlusion after contrast injection, (ii) reducing the frame rate, and (iii) pursuing maximal collimation on the region of interest. A total of 475 PVs were identified and successfully isolated. Median dose area product and fluoroscopy time were significantly shorter in Group 2 as compared to Group 1 [389 (285; 550) cGycm2 vs. 2168 (1355; 3490) cGycm2 (P < 0.0001) and 10 (8; 12) min vs. 14 (11; 19) min (P < 0.0001)]. Additionally, median time-to-isolation of the PVs was significantly shorter in Group 2 [44 (30; 65) s vs. 33 (20; 46) s (P < 0.0001)].

Conclusions

The implementation of an optimized fluoroscopy protocol significantly reduces radiation exposure in CB-based PVI without compromising acute efficacy and safety.

Second-generation cryoballoon ablation for recurrent atrial fibrillation after an index cryoballoon procedure: a staged strategy with variable balloon size

PURPOSE

Currently, information on the optimal approach of redo procedures for paroxysmal atrial fibrillation (PAF) is limited. Radiofrequency ablation is the preferred technique, with reported success rates of 50-70% at 1-2 years, whereas only few reports exist on redo cryoballoon (CB) ablations. We describe outcomes on a systematic approach of repeat procedures with a second-generation cryoballoon (CB-2) after a successful index CB ablation.

METHODS

Cohort study of 40 consecutive patients with recurrent PAF (55% male), median CHA2DS2-VASc score 1 (IQR 0-3). Per protocol, a staged variable balloon size strategy was followed with a different balloon size during the redo as compared to the index procedure. Minimal follow-up was 12 months (median 17 months [IQR 14-39]).

RESULTS

Overall, 120 pulmonary veins (PVs) (75%) showed chronic isolation: 64% (41/64) for first-generation cryoballoon (CB-1) and 82% (79/96) for CB-2 index procedures, respectively (p = 0.01). The overall mean number of reconnected PVs per patient was 1.0 (40/40): 1.4 for CB-1 and 0.7 for CB-2 index procedures (p = 0.008). Phrenic nerve palsies (n = 7) resolved before the end of the procedure. At 1 year, 70% of patients were free of recurrent AF. In multivariate analysis, the only independent predictor of recurrence was the number of prior cardioversions.

CONCLUSIONS

A systematic approach of repeat procedures with a CB-2 using a different balloon size than during the index CB ablation is safe, with acceptable 1-year outcomes. Future comparative studies on the optimal redo technique and approach are warranted to further improve rhythm control in AF.

Towards a tailored cryo-pulmonary vein isolation. Lessons learned from second-generation cryoballoon ablation

Second-generation cryoballoon ablation has emerged as an effective and practical approach for the treatment of atrial fibrillation. It gained the overall interest of the electrophysiology community due to its excellent success rates, and reproducible clinical outcomes comparable to the point-by-point radiofrequency technique. This technology offers several advantages including a fast learning curve and shorter procedure times making this device widely adopted in many EP-laboratories as an alternative strategy to conventional point-by-point radiofrequency ablation. As compared to its predecessor, the improved technical performances of the second-generation cryoballoon translated into favorable clinical outcomes, which are maintained in long-term follow-up. However, the ideal cryo-application duration and the adequate number of freeze-thaw cycles are not well established and predictors of durable electrical isolation are poorly known. This review provides some practical advices for a successful ablation using the second-generation cryoballoon.

The safety and efficacy of second-generation cryoballoon ablation plus catheter ablation for persistent atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Growing evidence suggests that second-generation cryoballoon ablation (2G-CB) is effective in patients with persistent atrial fibrillation (PerAF). The cornerstone of atrial fibrillation (AF) ablation is pulmonary vein isolation (PVI). The purpose of this study was to summarize the available data on the safety and mid-term (≥ 12 months) effectiveness of a 'PVI-only' strategy vs. a 'PVI-plus' strategy using 2G-CB in patients with PerAF.

METHODS

We searched the PubMed, EMBASE and Cochrane library databases for studies on 2G-CB for PerAF. Group analysis was based on the ablation approach: 'PVI-only' versus 'PVI-plus', the latter of which involved PVI plus other substrate modifications. Studies showing clinical success rates at a follow-up (FU) of ≥ 12 months were included. Complication rates were also assessed. Data were analyzed by applying a fixed effects model.

RESULTS

A total of 879 patients from 5 studies were analyzed. After a mid-term FU of 27 months, the overall success rate of 2G-CB for PerAF was 66.1%. In the 'PVI-plus' group, the success rate was 73.8%. In the 'PVI-only' group, the success rate was 53.6%. No heterogeneity was noted among studies (I2 = 0.0%, P = 0.82). Complications occurred in 5.2% of patients (P = 0.93), and the rate of phrenic nerve (PN) injury was 2.8% (P = 0.14). Vascular assess complications were the most frequent at 1.6% (P = 0.33). No death or myocardial infarction was reported.

CONCLUSION

'PVI-plus' involving 2G-CB seems to be safe and effective for treating PerAF.

Efficacy of temperature-guided cryoballoon ablation without using real-time recordings - 12-Month follow-up

Background

We sought to evaluate a temperature-guided approach of cryoballoon (CB) ablation without visualization of real-time recordings.

Methods and results

We analysed 166 patients (34.9% female, 60 ± 11 years) with paroxysmal or short-term persistent atrial fibrillation (AF). Comorbidities included diabetes mellitus (n = 28), coronary artery disease (n = 24), hypertension (n = 122), previous stroke or TIA > 3 months (n = 12). Cryoablation of the pulmonary veins (PV) was performed using first-generation (n = 78) and second-generation CB (n = 88). Two 5-minute freezes were performed for the first-generation and two 4-minute freezes for the second-generation CB with the intention to achieve a temperature drop below −40 °C. At 12-month follow-up, we observed overall freedom from AF in 92 patients (56.6%, mean time to AF recurrence 3.4 ± 2.9 months). There was a significant difference in freedom from AF between first-generation CB (45%) and second-generation CB (67%; p < 0.005). Complications were groin hematoma (4.8%) and phrenic nerve palsy (PVP) (2.4%). PVP disappeared after 12 months in all patients. Three patients developed cardiac tamponade (1.8%) that resolved without further sequelae after pericardiocentesis. Multivariate analysis revealed that only the achieved temperature in the right inferior PV (RIPV) was a predictor of long-term freedom from AF (OR 0.9; p = 0.014). Female gender was a predictor of AF recurrence (OR 6.1; p = 0.022).

Conclusion

Temperature-guided CB ablation without real-time recordings is feasible and safe without reducing the efficacy if second-generation CB is used. Deep nadir temperatures especially in the RIPV are necessary for long term-success.

Changes in f-wave characteristics during cryoballoon catheter ablation

OBJECTIVE

Changes in ECG-derived parameters are studied in atrial fibrillation (AF) patients undergoing cryoballoon catheter ablation.

APPROACH

Parameters characterizing f-wave frequency, morphology by phase dispersion, and amplitude are estimated using a model-based statistical approach. These parameters are studied before, during, and after ablation, as well as for AF type (paroxysmal/persistent). Seventy-seven (49/28 paroxysmal/persistent) AF patients undergoing de novo catheter ablation are included in the study, out of which 31 (16/15 paroxysmal/persistent) were in AF during the whole procedure. A signal quality index (SQI) is used to identify analyzable segments.

MAIN RESULTS

f-wave frequency decreased significantly during ablation (p  =  0.001), in particular after ablation of the inferior right pulmonary vein (p  <  0.05). Frequency and phase dispersion differed significantly between paroxysmal and persistent AF (p  =  0.001 and p  <  0.05, respectively).

SIGNIFICANCE

This study demonstrates that a decrease in f-wave frequency can be distinguished during catheter ablation. The use of an SQI ensures reliable analysis and produces results significantly different from those obtained without an SQI.

Efficacy of cryoballoon ablation in patients with paroxysmal atrial fibrillation without time to pulmonary vein isolation assessment

BACKGROUND

Real-time visualization of the electrical activity of the pulmonary veins (PV) is not always possible in the setting of atrial fibrillation (AF) cryoballoon ablation. We investigated the relation between the effective documentation of time to PV isolation and the clinical outcome in a cohort of patients with paroxysmal AF who underwent cryoballoon ablation.

METHODS

One thousand forty two consecutive patients were enrolled. An inner lumen mapping catheter was typically used to visualize real-time electrical activity inside the PVs.

RESULTS

Time to PV isolation was documented in all targeted PVs in 391 patients (Group 1), in 651 patients it was not possible to record PV potentials and assess time to PV isolation in at least one PV (Group 2). In Group 1 a longer procedure duration and ablation time were observed, while a longer fluoroscopy time was observed in Group 2. After a mean follow-up of 14 ± 11 months, 209/1042 (20%) patients had an atrial arrhythmia recurrence (20.2% in Group 1, 19.9% in Group 2, p = 0.25). Complications occurred in 54/1042 (5.2%) patients without any difference among the two study groups.

CONCLUSION

In our retrospective analysis, in about two thirds of patients undergoing cryoballoon ablation it was not possible to acutely assess time to PV isolation in all PVs. However, one-year freedom from clinically symptomatic atrial tachyarrhythmia was similar to that of patients in which time to PV isolation was documented in all targeted veins.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov (NCT01007474).

From early beginnings to elaborate tools: contribution of German electrophysiology to the interventional treatment of cardiac arrhythmias : The German Cardiac Society welcomes ESC in Munich 2018

Catheter ablation evolved from the early days of cardiac electrophysiology (EP), in which invasive electrophysiological studies were mainly a tool to find the correct diagnosis and to evaluate the most effective anti-arrhythmic drug for the patient. Today, catheter ablation is the most effective treatment option for patients suffering from supraventricular and ventricular arrhythmias. The understanding of cardiac arrhythmias and treatment strategies improved because of physicians and scientists from all over the world. The work of German cardiologists led to new achievements in the field of cardiac EP and catheter ablation. In this article, we summarize selective contributions of German EP centres in the field.

Reduction of radiation exposure in cryoballoon ablation procedures: a single-centre study applying intracardiac echocardiography and other radioprotective measures

Aims

The population treated with cryoballoon (CB) ablation is relatively young, and radiation protection is of major importance. We aimed to demonstrate that radiation exposure can be markedly reduced by intracardiac echocardiography (ICE) and optimized settings of the X-ray system.

Methods and results

We analysed 100 patients undergoing CB pulmonary vein isolation (PVI) for treatment of paroxysmal atrial fibrillation. In 50 consecutive patients (25 male, 59 ± 13 years; Group 1), we used ICE, skipped PV angiography prior to CB inflation, and avoided fluoroscopy whenever possible. Furthermore, we reduced the frame rate, minimized distance between patient and detector, and consequently applied collimation. These patients were compared with 50 similar preceding patients in Group 2 (29 male, 61 ± 12 years). Total fluoroscopy time was reduced from 18 ± 6 min in Group 2 to 12 ± 5 min in Group 1 (P < 0.001). Moreover, the dose area product was significantly lower (1555 ± 1219 vs. 4935 ± 2094 cGycm2, P < 0.001), total freezing time was significantly shortened (1855 ± 399 vs. 2121 ± 756 s, P = 0.031), and contrast media use was significantly reduced (66 ± 25 vs. 109 ± 27 mL, P < 0.001). At the same time, total procedure duration and complication rates did not differ significantly between both groups. After a 12 months follow-up, a similar percentage of patients was free from recurrences (74% in Group 1 vs. 78% in Group 2, P = 0.640).

Conclusion

Radiation exposure in CB PVI can be markedly reduced without prolonging procedure times, affecting the outcome or complication rates. Moreover, ICE seems to shorten total freezing time.

Combination of catheter ablation for non-valvular atrial fibrillation and left atrial appendage occlusion in a single procedure

Patients with atrial fibrillation (AF) have an increased risk of stroke and systemic embolism. Catheter ablation (CA) is increasingly applied for the treatment for drug-refractory AF; however, its long-term success rate is <50%. It has been proved that percutaneous left atrial appendage occlusion (LAAO) exerts the same efficacy as novel oral anti-coagulants [(N)OACs] in reducing thromboembolic events. The present study investigated whether a combined procedure of AF ablation and LAAO may be feasible and efficacious. CA was performed for patients with AF and a high risk of stroke according to their CHADS₂ or CHA₂DS₂-VASc score, and LAAO was performed using the Watchman device. A total of 25 patients (40% females; mean age, 64.2±3.5 years) who were treated between July 2016 and June 2017 were included in the present study. The median CHA2DS2-VASc score was 4.5 (range, 2-6) and the median HAS-BLED score was 3.17 (range, 1-7). Successful CA and LAAO were performed in 100% of cases. All patients met the criteria for successful LAAO. At the 6-month follow-up, complete sealing of the LAA was achieved in 23 patients (92%), while a minimal residual flow (<5 mm) was detected in 2 patients (8%). In 24 patients (96%), the administration of (N)OACs was terminated and aspirin administration was initiated at the 6-month follow-up. (N)OAC treatment was maintained in 1 patient (4%) on the basis of transient ischemic attack. During the 6-month follow-up period, 3 patients who had a recurrence of AF received a repeated ablation. In conclusion, the combination of CA and LAAO in a single procedure is feasible, safe and efficacious for patients with non-valvular AF at a high risk of stroke, and a contraindication regarding the use of (N)OACs.

A case of paroxysmal atrial fibrillation in a patient successfully treated by radiofrequency catheter ablation with a severely right-sided dislocation of the heart after a total right lung excision

A 72-year-old woman with symptomatic and drug-refractory paroxysmal atrial fibrillation (AF) underwent radiofrequency catheter ablation (RFCA). She had a history of a total right lung excision. Her chest X-ray and computed tomography (CT) revealed a severely sight-sided dislocation of the heart. Thus, the procedure was carefully performed under guidance of a CT, intracardiac echogram, atriography, and 3D mapping system. Finally, the AF was successfully treated by RFCA without any complications.

Comparing learning curves of two established "single-shot" devices for ablation of atrial fibrillation

PURPOSE

We compared the contour of learning curves of two "single-shot" devices used for pulmonary vein isolation (PVI) for safety and procedural data.

METHODS

We performed a retrospective analysis comparing the first 60 PVI performed at our center using a pulmonary vein ablation catheter (PVAC) array (39 male, mean age 57 years, 42 paroxysmal AF) to the first 60 first PVI using the Cryoballoon (44 male, mean age 59 years, 22 paroxysmal AF). Both groups were further divided into tertiles, where T1 regroups the first 20 ablations, T2 the following 20, and T3 the last 20 ablations.

RESULTS

The mean total procedure time was reduced by 24 min between T1 and T3 for the PVAC and 15 min for the Cryoballoon (p = 0.01). Fluoroscopy increased by 5 min, total ablation time was reduced by 7 min for PVAC (p = 0.02), and both times decreased respectively by 7 and 1 min for the Cryoballoon (p = ns). In the PVAC group, a mean rate of 0.16 (T1: n = 5; T2: n = 2; T3: n = 3) complications was observed while a rate of 0.16 (T1: n = 2; T2: n = 3; T3: n = 4) occurred in the CRYO group (p = ns). Severe complications defined as stroke, pericardial tamponade with need of pericardiocentesis and phrenic nerve palsy occurred in n = 4 in both groups (6.6%).

CONCLUSIONS

With either of the systems, no significant differences in the effect of the learning curve on the occurrence of adverse events were observed. However, the PVAC array seemed to have a steeper learning curve for procedure, as well as fluoroscopy time.

Radiofrequency Ablation versus Cryoablation in the Treatment of Paroxysmal Atrial Fibrillation: A Meta-Analysis

Background

Pulmonary vein isolation is commonly performed using radiofrequency energy with cryoablation gaining acceptance. We performed a meta-analysis of randomized controlled trials which compared radiofrequency versus cryoablation for patients with atrial fibrillation.

Methods

A systematic search strategy identified both published and unpublished articles from inception to November 10, 2016, in multiple databases. The primary outcomes for this meta-analysis were long-term freedom from atrial fibrillation at 12-month follow-up and overall postoperative complication rates. For all included studies, the methodological quality was assessed through the Cochrane Collaboration's tool for risk of bias.

Results

A total of 247 articles were identified with eight being included in this review as they satisfied the prespecified inclusion criteria. Overall, there was no significant difference in freedom from atrial fibrillation at ≥12-month follow-up between those receiving cryoballoon and radiofrequency ablation, respectively (OR = 0.98, CI = 0.67–1.43, I² = 56%, p=0.90). Additionally, the secondary outcomes of duration of ablation, fluoroscopy time, and ablation time failed to reach significance. Cryoballoon ablation had significantly greater odds of postoperative phrenic nerve injury at 12-month follow-up.

Conclusions

Our meta-analysis suggests that cryoballoon ablation provides comparable benefits with regard to freedom from atrial fibrillation at medium-term follow-up, fluoroscopy time, ablation time, operative duration, and overall complication rate in comparison to radiofrequency ablation.

Application of cryoablation for the treatment of atrial fibrillation in patients undergoing cardiac surgery: Our mid-term results

Background

In this study, we aimed to present mid-term results of concomitant argon-based cryoablation in patients undergoing cardiac surgery.

Methods

Between August 2014 and May 2016, 33 patients (17 males, 16 females; mean age 63.9 years; range 45 to 82 years) underwent the Maze procedure using cryoablation for the treatment of atrial fibrillation during a concomitant open cardiac operation. Robot-assisted procedures were used in 12 patients. Biatrial or isolated left atrial ablation was performed according to the underlying pathology. The rhythm assessment with 12-lead electrocardiography and 24-hour Holter, and recordings of atrial fibrillation-related medications, stroke or other thromboembolic events were evaluated by the cardiologist at 3 and 12 months postoperatively.

Results

Thirty patients (90.9%) were in sinus rhythm and three (9.1%) were in atrial fibrillation at the time of discharge. Cryoablation failed in three patients (n=2, 8.3% in isolated left atrial and n=1, 11.1% in biatrial group) following the operation in the mid-term. Among the patients, there was no in-hospital mortality and no major postoperative complications such as stroke, sepsis, renal failure requiring dialysis, and prolonged respiratory failure.

Conclusion

Concomitant surgical cryoablation is an effective method for the treatment of atrial fibrillation, when performed concomitantly with other cardiac surgical procedures and results in very low atrial fibrillation recurrence, even in robotic surgery.

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.

How to Prevent, Detect and Manage Complications Caused by Cryoballoon Ablation of Atrial Fibrillation

Atrial fibrillation is the most common cardiac arrhythmia and the prevalence is increasing every year. Patients who fail to maintain sinus rhythm with use of anti-arrhythmic drug therapy are referred for catheter ablation. Cryoballoon (CB) ablation has emerged as an effective and alternative treatment option to traditional point-by-point radiofrequency ablation, but there can be complications. This article reviews the incidence, presentation, risk factors, management and preventative strategies of three major complications associated with CB ablation: phrenic nerve injury, atrial oesophageal fistula and bronchial injury. Although these complications are rare, electrophysiologists should institute measures to identify high-risk patients, implement best-practice techniques to minimise risks and maintain a high index of suspicion to recognise the complications quickly and implement correct treatment strategies.

Dissociated pulmonary vein activity after cryoballoon ablation and radiofrequency ablation for atrial fibrillation: a propensity score-matched analysis

Cryoballoons (CBs) have proven to be effective for achieving pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF). Dissociated PV activity (DPVA) after successful radiofrequency PVI is sometimes observed inside the PV and has been found to prove the achievement of electrical disconnection from the left atrium. However, little is known about the incidence or characteristics of DPVA after CB-PVI. The aim of this study was to compare the incidence and characteristics of DPVA in patients undergoing CB and radiofrequency (RF) ablation for AF. Two hundred and ninety-four propensity score-matched patients from 440 consecutive patients who underwent initial catheter ablation for paroxysmal AF were included in the present study (CB-PVI 147, RF-PVI 147). DPVA was more frequently observed after CB-PVI than after RF-PVI (32 vs. 19% of the PVs, P < 0.001), especially in the left superior PV (52 vs. 29%, P < 0.001) and left inferior PV (22 vs. 7%, P < 0.001). The AF-free rate after the initial ablation in the patients with and without DPVA was similar in both the CB (P = 0.23) and RF (P = 0.39) groups. During repeat ablation procedures for recurrent AF, PV reconnection was similarly observed in PVs with and without DPVA during the initial procedure, both in the CB (30 vs. 44%, P = 0.29) and RF (65 vs. 58%, P = 0.41) groups. DPVA was more frequently observed after CB-PVI than after RF-PVI. The presence of DPVA was not related to the ablation outcome or chronic PV reconnection following CB-PVI.

Cryoballoon ablation in atrial fibrillation: Advantages and drawbacks

Pulmonary vein isolation is the cornerstone of atrial fibrillation ablation and is effective for preventing arrhythmias recurrences, especially in patients with paroxysmal atrial fibrillation. During the last years, cryoballoon ablation has emerged as an unquestionable alternative approach to radiofrequency ablation. Many non-randomized and randomized trials have proven undoubtedly that cryoballoon ablation displays similar efficacy and overall safety profile, when compared to radiofrequency ablation for the treatment of patients with drug-refractory paroxysmal atrial fibrillation. These results have been obtained in all types of pulmonary veins anatomical subsets, which confirms that there is no need to select patients according to the latter. The value of cryoablation in the setting of short persistent atrial fibrillation still needs more evidence. Importantly, cryoballoon ablation seems to be less operator-dependent and more reproducible than radiofrequency for the isolation of pulmonary veins.