Electrophysiologic and anatomic factors predictive of a need for touch‐up radiofrequency application for complete pulmonary vein isolation: Comparison between hot balloon‐ and cryoballoon‐based ablation

Bayesian network meta-analysis comparing hot balloon, laser balloon and cryoballoon ablation as initial therapies for atrial fibrillation

BACKGROUND

Balloon-based catheter ablation (CA) technologies, including hot balloon ablation (HBA), laser balloon ablation (LBA) and cryoballoon ablation (CBA) have been introduced in recent years as alternatives to conventional radiofrequency ablation therapy for atrial fibrillation (AF). However, the results remain controversial concerning the optimal approach. Thus, we conducted a network meta-analysis (NMA) to comprehensively evaluate the efficacy and safety of HBA, LBA and CBA.

METHODS

Clinical trials comparing the efficacy and safety of HBA, LBA and CBA were identified through a systematic search up to October 2022. The primary outcomes of interest were the recurrence of AF and procedure-related complications.

RESULTS

Twenty clinical trials with a total of 1,995 patients were included in the meta-analysis. The NMA results demonstrated that HBA, LBA and CBA had comparable AF recurrence rates (HBA vs. CBA: odds ratio OR = 0.88, 95% credible interval CrI: 0.56-1.4; LBA vs. CBA: OR = 1.1, 95% CrI: 0.75-1.5; LBA vs. HBA: OR = 1.2, 95% CrI: 0.70-2.0) and procedure-related complications (HBA vs. CBA: OR = 0.93, 95% CrI: 0.46-2.3; LBA vs. CBA: OR = 1.1, 95% CrI: 0.63-2.1; LBA vs. HBA: OR = 1.2, 95% CrI: 0.44-2.8). The surface under the cumulative ranking curve (SUCRA) suggested that HBA may be the optimal approach concerning the primary outcomes (SUCRA = 74.4%; 61.1%, respectively). However, HBA (40.1%) had a significantly higher incidence of touch-up ablation (TUA) than LBA (8.5%, OR = 2.8, 95% CrI: 1.1-7.1) and CBA (11.9%, OR = 3.7, 95% CrI: 1.9-7.5). LBA required more procedure time than CBA [mean difference (MD = 32.0 min, 95% CrI: 19.0-45.0 min)] and HBA (MD = 26.0 min, 95% CrI: 5.6-45.0 min), but less fluoroscopy time than HBA (MD = -9.4 min, 95% CrI: -17.0--2.4 min).

CONCLUSIONS

HBA, LBA and CBA had comparable efficacy and safety as initial treatments for AF. HBA ranked highest in the primary outcomes, but at the cost of a higher incidence of TUA and longer fluoroscopy time.

SYSTEMATIC REVIEW REGISTRATION

www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022381954, identifier: CRD42022381954.

Chronic Ablation Lesions after Cryoballoon and Hot Balloon Ablation of Atrial Fibrillation

BACKGROUND

Chronological changes in ablation lesions after cryoballoon ablation (CBA) and hot balloon ablation (HBA) of atrial fibrillation (AF) remain unclear.

METHODS

Of 90 patients who underwent initial balloon-based catheter ablation of AF and cardiac magnetic resonance imaging (cMRI) 3 months after ablation, data from 48 propensity score-matched patients (24 per group; 34 males; age 62±10 years) were analyzed. High-density pulmonary vein-left antrum (PV-LA) voltage mapping was performed after PV isolation, and low voltage areas around the PV ostia were defined as the total acute ablation lesion area (cm²). cMRI-derived dense fibrotic tissue localized around PVs was defined as the total chronic ablation lesion area (cm²). The percentage of total ablation lesion areas to total PV-LA surface area (%ablation lesion) was calculated during each phase, and %acute ablation lesion and %chronic ablation lesion areas were compared in patients who had undergone CBA and HBA.

RESULTS

The %acute ablation lesion area was larger for the CBA group than for the HBA group (30.8±5.8% vs. 23.0±5.5%, p < 0.001). There was no difference in %chronic cMRI-derived ablation lesion area (24.8±10.8% vs. 21.1±11.6%, p = 0.26) between groups. The rates of chronic AF recurrence were 12.5% and 8.3%, respectively (p = 0.45; log-rank test). LA volume and LA surface area were strongly associated with AF recurrence, but %chronic ablation lesion area was not (27±8% vs. 23±12%, p = 0.39).

CONCLUSION

Large acute ablation lesions after CBA were smaller during the chronic phase. The size of chronic ablation lesions and the rate of AF recurrence were both similar for CBA and HBA.

Effects of Hot Balloon vs. Cryoballoon Ablation for Atrial Fibrillation: A Systematic Review, Meta-Analysis, and Meta-Regression

Background: Balloon-based catheter ablations, including hot balloon ablation (HBA) and cryoballoon ablation (CBA), have rapidly emerged as alternative modalities to conventional catheter atrial fibrillation (AF) ablation owing to their impressive procedural advantages and better clinical outcomes and safety. However, the differences in characteristics, effectiveness, safety, and efficacy between HBA and CBA remain undetermined. This study compares the characteristic and prognosis differences between HBA and CBA.

Methods: Electronic search was conducted in six databases (PubMed, Embase, Cochrane Library, Web of Science, ClinicalTrial.gov, and medRxiv) with specific search strategies. Eligible studies were selected based on specific criteria; all records were identified up to June 1, 2021. The mean difference, odds ratios (ORs), and 95% confidence intervals (CIs) were calculated to evaluate the clinical outcomes. Heterogeneity and risk of bias were assessed using predefined criteria.

Results: Seven studies were included in the final meta-analysis. Compared with CBA, more patients in the HBA group had residual conduction and required a higher incidence of touch-up ablation (TUA) [OR (95% CI) = 2.76 (2.02–3.77), P = 0.000]. The most frequent sites of TUA were the left superior pulmonary veins (PVs) in the HBA group vs. the right inferior PVs in the CBA group. During HBA surgery, the left and right superior PVs were more likely to have a higher fluid injection volume. Furthermore, the procedure time was longer in the HBA group than in the CBA group [weighted mean difference (95% CI) = 14.24 (4.39–24.09), P = 0.005]. Patients in the CBA group could have an increased risk of AF occurrence, and accepted more antiarrhythmic drug therapy; however, the result was insignificant.

Conclusions: HBA and CBA are practical ablation approaches for AF treatment. Patients who received HBA had a higher incidence of TUA and longer procedure time. Clinical outcomes during the mid-term follow-up between HBA and CBA were comparable.

Systematic Review Registration:https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=259487, identifier: CRD42021259487.

Utility of hot-balloon-based pulmonary vein isolation under balloon surface temperature monitoring: First clinical experience

INTRODUCTION

A new hot balloon system that registers balloon surface temperature (BST) during energy delivery is now available for clinical use in Japan. This study sought to investigate the utility of BST measurement for achievement of pulmonary vein isolation (PVI) by a single-shot energy delivery strategy during hot balloon ablation (HBA).

METHODS

We applied and tested the system in 30 consecutive patients undergoing HBA for paroxysmal or early-persistent atrial fibrillation (AF). We also performed real-time PV potential monitoring using a circular catheter.

RESULTS

Acute PVI was achieved with single hot balloon shots in 88% (106/120) of the PVs. Real-time BSTs and PV potentials were recorded in all cases. Mean BST at documentation of PVI was 49.4°C, and acute reconnections were observed in most cases (86%, 12/14) in which the single-shot technique was ineffective. Time-to-isolation (TTI) (23.1 ± 8.7 s vs. 36.3 ± 9.3 s, p < .01) and median BST (59.9 ± 2.6°C vs. 55.7 ± 1.9°C, p < .01) differed significantly between cases in which PVI was achieved (vs. those in which PVI was not achieved). Multivariable analysis revealed strong association between both TTI and median BST and acute PVI. The best median BST cutoff value for achieving PVI with a single shot was >58.7°C (sensitivity 67.0%, specificity 100%).

CONCLUSION

Our data suggest that real-time BST monitoring during energy applications is useful for predicting achievement of acute PVI by a single shot during HBA.

Early experiences with three types of balloon-based ablation catheters in patients with paroxysmal atrial fibrillation

Background

Although balloon-based ablation catheters are expected to improve the feasibility and quality of pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF), they must be introduced to physicians in the proper setting to ensure their correct usage.

Objective

To identify the optimal clinical settings for learning the techniques for 3 balloon-based ablation catheters (Cryoballoon, Hotballoon, and Laserballoon).

Methods

We introduced 3 balloon catheters in 50 consecutive patients with paroxysmal AF each during the introduction periods. Clinical parameters were compared among the groups and between these groups and their steady-state controls.

Results

The completion rate of PVI by sole balloon procedures was 56% with the Hotballoon catheter, which was lower than those of the Cryoballoon and Laserballoon catheters (each 88%). Radiofrequency touch-up was most frequently required at the bottom aspect of the inferior pulmonary veins (PVs) in the Cryoballoon group and at the anterior aspect of the superior PVs in the Hotballoon and Laserballoon groups. The Laserballoon catheter had the longest average PVI procedural time (89.2 ± 40 vs 58.4 ± 22 minutes for Hotballoon, 65.1 ± 25 minutes for Cryoballoon, P < .001), but the difference was ultimately removed by the learning curve. There was no significant difference in the major complication or recurrence-free survival rates among the catheter types.

Conclusions

All 3 balloon-based catheter types allowed feasibility and quality for PVI, even during the learning period. To introduce these new catheters without complications, an experiences of 20 cases with specific clinical settings should be met for each catheter type.

Virtual and real assessment of a wide antral ablated region in atrial fibrillation patients using the hot balloon system

The hot balloon system has become widely used for atrial fibrillation ablation and also has software for preoperative computer simulation. The computer model may be useful for predicting the extent of a wide planar ablation region in the left atrium.

A porcine study of the area of heated tissue during hot-balloon ablation: Implications for the clinical efficacy and safety

INTRODUCTION

Hot-balloon ablation depends solely on thermal conduction, and myocardial tissue is ablated by only conductive heating from the balloon surface. Despite growing clinical evidence of the efficacy and safety of hot-balloon ablation for atrial fibrillation (AF), the actual tissue temperature and the mechanism of heating during such ablation has not been clarified. To determine, by means of a porcine study, the temperatures of tissues targeted during hot-balloon ablation of AF performed with hot-balloon set temperatures of 73°C or 70°C, in accordance with the temperatures now used clinically.

METHODS

After a right thoracotomy, thermocouples with markers were implanted epicardially on the superior vena cava (SVC) and pulmonary veins (PVs) in six pigs. The tissue temperatures during hot-balloon ablation (balloon set temperatures of 73°C and 70°C, 180 s/PV) were recorded, and the maximum tissue temperatures and fluoroscopically measured distance from the balloon surface to the target tissues were assessed.

RESULTS

Sixteen SVC- and 18 PV-targeted energy deliveries were performed. Full-thickness circumferential PV lesions were created with all hot-balloon applications. A significant inverse relation was found between the recorded tissue temperatures and distance (r = -.67; p < .001) from the balloon surface. No tissue temperature exceeded either of the balloon set temperatures. The best distance cutoff value for achieving lethal tissue temperatures more than 50°C was 3.6 mm.

CONCLUSION

The hot-balloon set temperature, energy delivery time, and tissue temperature data obtained in this porcine study supported the clinical efficacy and safety of the hot-balloon ablation as currently practiced in patients with AF.

Keeping it Simple: Balloon Devices for Atrial Fibrillation Ablation Therapy

Atrial fibrillation is a common disease of increasing prevalence. Catheter ablation has evolved into an established therapeutic option that mainly aims to electrically isolate the pulmonary veins from atrial myocardium. The traditional method comprises point-by-point radiofrequency current ablation guided by electroanatomical mapping and has proven to be effective and safe in experienced hands. However, this approach is technically highly demanding and associated with a long learning curve, limiting its widespread utilization. To address these shortcomings, simplified ablation tools for pulmonary vein isolation are needed. In this context, balloon devices promise to ease the procedure by approaching the entire orifice of a targeted pulmonary vein in a single maneuver. This requires less catheter manipulation in the left atrium and often allows ablation of a large volume of tissue with a single application of ablative energy. Two balloon devices-one using cryoenergy, the other laser energy-have already been established in clinical routine and have demonstrated noninferiority when compared with radiofrequency ablation in large randomized trials. More balloon devices are on the verge of being introduced into clinical practice and bear the potential to expand the interventional electrophysiologist's armamentarium when treating atrial fibrillation. The authors review the use of the established balloon devices available for atrial fibrillation ablation and provide a detailed outlook on upcoming balloon technologies, including 3 different balloons utilizing radiofrequency energy as well as a novel cryoballoon.

Catheter Ablation of Atrial Fibrillation: State of the Art and Future Perspectives

PURPOSE OF REVIEW

Atrial fibrillation (AF), the most common sustained arrhythmia, is associated with high rates of morbidity and mortality. Maintenance of stable sinus rhythm (SR) is the intended treatment target in symptomatic patients, and catheter ablation aimed at isolating the pulmonary veins provides the most effective treatment option, supported by encouraging clinical outcome data. A variety of energy sources and devices have been developed and evaluated. In this review, we summarize the current state of the art of catheter ablation of AF and describe future perspectives.

RECENT FINDINGS

Catheter ablation is a well-established treatment option for patients with symptomatic AF and is more successful at maintaining SR than antiarrhythmic drugs. Antral pulmonary vein isolation (PVI) as a stand-alone ablation strategy results in beneficial clinical outcomes and is therefore recommended as first-line strategy for both paroxysmal and persistent AF. While radiofrequency-based PVI in conjunction with a three-dimensional mapping system was for many years considered to be the "gold standard", the cryoballoon has emerged as the most commonly used alternative AF ablation tool, especially in patients with paroxysmal AF. Patients with persistent or long-standing persistent AF and with arrhythmia recurrence after previous PVI may benefit from additional ablation strategies, such as substrate modification of various forms or left atrial appendage isolation. New technologies and techniques, such as identification of the AF sources and magnetic resonance imaging-guided substrate modification, are on the way to further improve the success rates of catheter ablation for selected patients and might help to further reduce arrhythmia recurrence.

CONCLUSIONS

Pulmonary vein isolation is the treatment of choice for symptomatic patients with paroxysmal and persistent drug-refractory AF. The reconnection of previously isolated pulmonary veins remains the major cause of AF recurrence. Novel ablation tools, such as balloon technologies or alternative energy sources, might help to overcome this limitation. Patients with non-paroxysmal AF and with AF recurrence might benefit from alternative ablation strategies. However, further studies are warranted to further improve our knowledge of the underlying mechanisms of AF and to obtain long-term clinical outcomes on new ablation techniques.