Verification of a novel atrial fibrillation cryoablation dosing algorithm guided by time-to-pulmonary vein isolation: Results from the Cryo-DOSING Study (Cryoballoon-ablation DOSING Based on the Assessment of Time-to-Effect and Pulmonary Vein Isolation Guidance)

Heart Rhythm. 2017 Sep;14(9):1319-1325. doi: 10.1016/j.hrthm.2017.06.020. Epub 2017 Jun 15.

Abstract

Background: There are no recommendations on the optimal dosing for cryoablation of atrial fibrillation (Cryo-AF).

Objective: The purpose of this study was to develop and prospectively test a Cryo-AF dosing protocol guided exclusively by time-to-pulmonary vein (PV) isolation (TT-PVI) in patients undergoing a first-time Cryo-AF.

Methods: In this multicenter study, we examined the acute/long-term safety/efficacy of Cryo-AF using the proposed dosing algorithm (Cryo-AFDosing; n = 355) against a conventional, nonstandardized approach (Cryo-AFConventional; n = 400) in a nonrandomized fashion.

Results: Acute PV isolation was achieved in 98.9% of patients in Cryo-AFDosing (TT-PVI = 48 ± 16 seconds) vs 97.2% in Cryo-AFConventional (P = .18). Cryo-AFDosing was associated with shorter (149 ± 34 seconds vs 226 ± 46 seconds; P <.001) and fewer (1.7 ± 0.8 vs 2.9 ± 0.8; P <.001) cryoapplications, reduced overall ablation (16 ± 5 minutes vs 40 ± 14 minutes; P <.001), fluoroscopy time (13 ± 6 minutes vs 29 ± 13 minutes; P <.001), left atrial dwell time (51 ± 14 minutes vs 118 ± 25 minutes; P <.001), and total procedure time (84 ± 23 minutes vs 145 ± 49 minutes; P <.001) but similar nadir balloon temperature (-47°C ± 8°C vs -48°C ± 6°C; P = .41) and total thaw time (43 ± 27 seconds vs 45 ± 19 seconds; P = .09) as compared to Cryo-AFConventional. Adverse events (2.0% vs 2.7%; P = .48), including persistent phrenic nerve palsy (0.6% vs 1.2%; P = .33) and 12-month freedom from all atrial arrhythmias (82.5% vs 78.3%; P = .14), were similar between Cryo-AFDosing and Cryo-AFConventional. However, Cryo-AFDosing was specifically associated with fewer atypical atrial flutters/tachycardias during long-term follow-up (8.5% vs 13.5%; P = .02) as well as fewer late PV reconnections at redo procedures (5.0% vs 18.5%; P <.001).

Conclusion: A novel Cryo-AF dosing algorithm guided by TT-PVI can help individualize the ablation strategy and yield improved procedural endpoints and efficiency as compared to a conventional, nonstandardized approach.

Keywords: Algorithm; Atrial fibrillation; Catheter ablation; Cryoablation; Cryoballoon; dosing.

Publication types

  • Multicenter Study

MeSH terms

  • Algorithms
  • Atrial Fibrillation / diagnosis
  • Atrial Fibrillation / physiopathology
  • Atrial Fibrillation / surgery*
  • Cardiac Catheterization
  • Catheter Ablation / methods*
  • Cryosurgery / instrumentation*
  • Equipment Design
  • Female
  • Fluoroscopy / methods
  • Follow-Up Studies
  • Heart Conduction System / physiopathology
  • Heart Conduction System / surgery*
  • Humans
  • Male
  • Middle Aged
  • Pulmonary Veins / surgery*
  • Recurrence
  • Retrospective Studies
  • Surgery, Computer-Assisted / methods*
  • Tachycardia, Paroxysmal / diagnosis
  • Tachycardia, Paroxysmal / physiopathology
  • Tachycardia, Paroxysmal / surgery*
  • Time Factors