Abstract 20102: Time-to-Effect Based Cryoballoon Dosing to Achieve Permanent Pulmonary Vein Isolation -The First Chronic Study in Canine Model
Background: Cryoballoon ablation (CB) is an effective treatment for Paroxysmal Atrial Fibrillation (PAF). Current time-based dosing may be inadequate to characterize the cryo-thermal energy transfer and collateral injury pattern. Physiologic end-point such as time to effect (TTE) (i.e. acute loss of pulmonary vein (PV) signals) can be monitored during ablation but correlation to long-term pulmonary vein isolation (PVI) has not been established. This study evaluated acute and chronic PVI results and collateral tissue damage with a goal of determining a TTE dosing regimen to optimize CB efficacy and safety.
Methods: 30 PVs (left and right superior branches) from 15 healthy mongrel dogs (avg. 30.5kg) were randomized into 5 dosing groups: 1. TTE+60 seconds; 2. TTE+90 seconds; 3. TTE+120seconds; 4. TTE+150 seconds; 5. 2x180 seconds. Ablations were performed with a 23mm Arctic Front Advance® CB and TTE measured by The Achieve™ Mapping Catheter. Esophageal temperature was monitored using the Circa S-CathTM and endoscopy. Animals were survived for 30-34 days and repeat assessment of PVI and collateral tissue was performed with gross and histopathological examination.
Results: All PVs in all 5 groups were acutely isolated. At 1 month end-study, 27 of 30 PVs remained isolated. TTE was significantly longer in incomplete occlusion (>70 seconds), and led to incomplete PVI in 2/30 PVs; even longer ablation time of 220 seconds did not create permanent PVI. Conversely, when TTE was short of < 30 seconds, just an additional 60 seconds was able to create permanent isolation even with a total ablation time of only 75 seconds. All ablations were well demarcated, wide bands with no strictures or thrombi. No collateral esophageal injury was seen despite 2x 180 seconds of ablation, likely due to proximity since no significant reduction of intraluminal temperature was observed.
Conclusions: In the canine model, shorter TTE correlates with permanent PVI. TTE based dosing with good occlusion of PVs can lead to permanent PVI as low as TTE + 60s, and may minimize collateral injury by minimizing unnecessarily long ablation. Additional ablation subgroups may be required to better delineate the physiology of TTE to permanence of PVI. Correlation to human PVI and 28mm balloon will be needed.
Author Disclosures: W. Su: Research Grant; Modest; St. Jude Medical. Research Grant; Significant; Medtronic Inc. Honoraria; Modest; St Jude Medical. Honoraria; Significant; Medtronic Inc. N. Kirchhof: Employment; Significant; Medtronic Inc. E. Grassl: Employment; Significant; Medtronic Inc. A. Williams: None. D. Wittenberger: Employment; Significant; Medtronic Inc.
- © 2016 by American Heart Association, Inc.