Introduction Pulmonary vein isolation PVI is an

Introduction Pulmonary vein isolation (PVI) is an established strategy of paroxysmal atrial fibrillation (PAF) ablation [1–3]. Radiofrequency catheters have been the standard for AF ablation; however, PVI using balloon-based ablation has been increasingly adopted by electrophysiology laboratories around the world [4–6]. The second-generation cryoballoon (CB2) (Arctic Front AdvanceTM, Medtronic, MN, USA), which is designed to achieve more uniform cooling across the entire distal hemisphere of the balloon, has been recently launched on the market for the treatment of PAF. CB2 ablation is effective for the treatment of PAF; however, there is some debate concerning the optimal number of freezing cycles, the ideal freezing duration of each cycle, and the appropriate patient characteristics for CB2 ablation. No prospective, randomized clinical CB2 trials have been conducted to investigate the need for an additional (bonus) freezing 740 Y-P after PVI is achieved. We therefore conducted an investigation of the optimal freezing cycles in AF patients treated with CB2 ablation.
Material and methods
Results
Discussion CB2 ablation provides more reproducible results and reduced procedural times than conventional radiofrequency catheter ablation [15,16]. In addition, some studies have reported a high rate of PVI durability and a high long-term AF free rate of about 80% using the CB2 ablation procedure [17]. Some clinical reports describing cryobiology stress the need for repetitive freezing cycles to extend the lethal effect at the periphery of the target tissue [18,19]. On the other hand, recent studies on the CB2 have shown that a single 3-min freezing cycle may be sufficient for a durable PVI [7,20]. Chierchia et al. reported the initial experience of 3-min freeze cycles using the CB2 [7]. Fifty-two consecutive patients were included in the study. In the first 24 (46%) consecutive patients, an additional freezing cycle after PVI was performed, and it was not given in the subsequent 28 patients (54%). As a result, there were no differences in the recurrence rate between patients with and without an additional freezing cycle after PVI. However, patients were not randomly assigned, and the learning curve might have affected the results in the study about the initial experience with CB2 ablation. We therefore assess the optimal freezing cycles in AF patients treated with CB2 ablation in this prospective, multicenter, and randomized clinical trial.
Conclusions
Role of the funding source The AD-Balloon study is partly supported by the Intramural Research Fund (25-4-7, Kusano) for Cardiovascular Diseases of National Cerebral and Cardiovascular Center. There is no specific sponsor that has a role in the study design or conduct of the study, collection of the data, its analysis or its interpretation, or in the preparation of the present manuscript. The authors have full access to all data and take full responsibility for the integrity of the data in this study, and for the decision to submit this manuscript for publication.
Conflict of interest
Introduction Catheter ablation of cavotricuspid isthmus (CTI)-dependent atrial flutter (typical AFL) is a therapy with a high success rate [1–4]. However, typical AFL often coexists with atrial fibrillation (AF), and AF frequently appears after catheter ablation of typical AFL. Several studies have reported the prevalence of AF after catheter ablation of typical AFL to range from 21% to 43% [1–5]. Some reports have described an association between AF and typical AFL; however, previous reports showed that AF was an initiator of typical AFL only in animal models and in postoperative open-heart patients with epicardial electrograms recorded by a wire electrode placed temporarily [6,7]. In contrast, one report showed that pulmonary vein (PV) firing plays a role in the transition of typical AFL to AF [8]. However, no reports have revealed the contribution of PV firing to the initiation of typical AFL in the clinical setting. This study aimed to reveal the mechanisms of the initiation of typical AFL and the association between typical AFL and AF, and especially PV firing.