Hot balloon versus cryoballoon ablation in patients with atrial fibrillation: a systematic review and meta-analysis
Authors: Papathanasiou K , Giotaki S , Kossyvakis C , Kazantzis D , Vrachatis D , Deftereos G , Raisakis K , Kaoukis A , Avramides D , Siasos G , Giannopoulos G , Deftereos S 
Published: May 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Atrial fibrillation (AF) incidence is expected to increase more than 60% in the following 30 years. Catheter ablation is the treatment of choice for medically intractable AF with arrhythmia recurrence remaining an unsolved issue.

Purpose
We systematically reviewed existing literature to compare the efficacy of hot balloon (HBA) versus cryoballoon ablation (CBA).

Methods
PubMed, Scopus, ClinicalTrials.gov, medRxiv and Cochrane Library (according to PRISMA guidelines) were scrutinized for relevant articles up to 2 December 2021. Eligible studies had to compare clinical outcomes (arrhythmia recurrence rates or/and procedural data or/and safety outcomes) between patients undergoing HBA and CBA for AF. Quality assessment of studies was conducted via the Newcastle-Ottawa Scale (high quality≥ 7, moderate 4-6, poor &lt;4). Statistical pooling was performed according to a random-effect model with generic inverse-variance weighting of odds ratios and mean differences computing risk estimates with 95% confidence intervals. The presence of heterogeneity among studies was evaluated under the Cochran Q chi-square test. I² values of 25%, 50% and 75% have been assigned adjectives of low, moderate, and high heterogeneity. Publication biases were assessed by visual inspection of funnel plots.

Results
PRISMA study search and individual study characteristics are presented in Figure 1. Literature search identified 131 studies, 5 of which (evaluating 513 patients) met inclusion criteria. Patients undergoing HBA demonstrated similar long term recurrence rate as compared to CBA treated controls (OR: 0.68; 95% CI: 0.38-1.22; p-value: 0.19; I2: 0%). Procedural aspects, such as touch-up radiofrequency ablation (per pulmonary vein), procedure time (min) and fluoroscopic time (min) did not differ among treatment arms (OR: 1.79; 95% CI: 0.84-3.83; p-value: 0.13, I2: 80%, MD: 9.69; 95% CI: -2.78-22.16; p-value: 0.13, I2: 63%, and OR: 1.03; 95% CI: -9.50-7.44; p-value: 0.81, I2: 87%, respectively). Regarding safety outcomes (Figure 1), the small number of the reported events precluded us from analyzing these data. Yet, tamponade and phrenic nerve injury were infrequent in both modalities; pulmonary vein stenosis of at least moderate severity (&gt;50% luminal narrowing) was reported in 18 instances in the HBA arm as compared to zero events in the CBA arm. Of note, all events were asymptomatic. Quality assessment scores are shown in Figure 1. Four studies were of high quality and one study was of moderate quality. Funnel-plot distributions of the pre-specified outcomes indicated absence of publication bias for all outcomes. High statistical heterogeneity and the small number of patients included are the main limitations of this study.

Conclusion
Hotballoon ablation is a promising therapeutic option for patients suffering from AF, featuring comparable efficacy and procedural outcomes with cryoablation. Safety outcomes, especially PV stenosis, mandate further evaluation.