Comparison of Extended Cryoballoon Ablation, Standard Cryoballoon Ablation, and Radiofrequency Catheter Ablation in Patients With Persistent Atrial Fibrillation: A Multicenter, Randomized Controlled Clinical Trial

The method of ablation, size of balloon, freezing time, and booster freezing will be decided by the participating center's policy or physician's discretion. Ablation strategies described above are highly recommended for all participants.

Additional posterior wall isolation should be performed by single 120 to 180 second CB application delivered at each site. Maximal posterior wall debulking should be attempted, although complete isolation may not always be achievable, as we considered that a large scar created by the CB application would provide sufficient anti-arrhythmic effects in terms of suppressing AF. The number and duration of CB application should be recorded in the case report form. Successful posterior wall isolation should be determined by 3-dimensional electro-anatomical mapping or differential pacing. The method and achievement of posterior wall isolation should be recorded in the case report form.

Application of TTI + 2 minutes or 180 seconds single-freezing is recommended when time-to-isolation (TTI) <60 seconds. Additional 120 seconds of booster-freezing after TTI + 2 or 180 seconds initial freezing is recommended when TTI value >60 seconds, or PV potentials were not discernable in the Achieve multipolar catheter. If temperatures below -40°C cannot be achieved due to improper occlusion or TTI > 90 seconds, freezing should be discontinued and reposition of balloon is recommended. Segmental ablation is allowed when the proper occlusion of PV by balloon cannot be achieved. Continuous phrenic capture should be monitored during the procedure in the right PVs to avoid phrenic nerve injury. Stop ablation immediately if phrenic nerve damage is suspected. No further ablation would be performed if the phrenic nerve damage is suspected. Touch-up ablation using irrigated radiofrequency ablation catheter would be permitted with conventional mapping method.

CARTO system (Biosense-Webster, USA): Ablation index (AI) CLOSE protocol . Navistar Smart-touch surround-flow catheter; 25-40 watts of energy; 40 seconds time limit; 10-30 gram of contact force; 40 seconds time limit; targeting AI value of 550 in anterior wall and 400 in the posterior wall; interlesion distance ≤6mm; using automatic lesion annotation (Visitag™) - type 3 tagging, 3mm stability for 5 seconds, force >5g over 50% of time; target AI value could be reduced (450 in anterior wall and 350 in posterior wall) according to the participating center's policy.

Ensite NavX system (Abbott, USA) :

TactiCath™ Quartz ablation catheter; delivering 25-35 watts of energy; 40 seconds time limit; 10-30 gram of contact force; using automatic lesion annotation (Automark Module), target lesion index value of 5-5.5 in the posterior wall and 5.5-6 in the anterior wall.