Bonus-freeze: benefit or risk? Two-year outcome and procedural comparison of a "bonus-freeze" and "no bonus-freeze" protocol using the second-generation cryoballoon for pulmonary vein isolation

Abstract

Background: Second-generation cryoballoon based pulmonary vein isolation has demonstrated encouraging acute and mid-term clinical outcome. Customarily, a bonus-freeze is applied after successful pulmonary vein isolation.

Objective: To compare the long-term clinical outcome and safety profile of a bonus-freeze and a no bonus-freeze protocol.

Methods: A total of 120 consecutive patients with paroxysmal [95/120 (79 %)] or persistent atrial fibrillation [25/120 (21 %)] underwent CB2-based PVI. Freeze-cycle duration was 240 s. In the first 60 patients a bonus-freeze was applied after successful PVI (group 1), while in the following 60 patients the bonus-freeze was omitted (group 2).

Results: Procedure and fluoroscopy times were significantly shorter in group 2 [113.8 ± 32 vs 138.2 ± 29 min (p = 0.03) and 19.2 ± 6 vs 24.3 ± 8 min (p = 0.02)]. No differences in procedural complications were found. During a mean follow-up of 849 ± 74 (group 1) and 848 ± 101 days (group 2, p = 0.13) 69 % of patients (group 1) and 67 % of patients (group 2) remained in stable sinus rhythm without any differences between the groups (p = 0.69).

Conclusions: Freedom from atrial fibrillation after second-generation cryoballoon based pulmonary vein isolation and a follow-up of >2 years is comparable when applying a bonus- and a no bonus-freeze protocol, while procedure and fluoroscopy times are significantly shorter when omitting the bonus-freeze. No differences in periprocedural complications were identified.

Keywords: Atrial fibrillation; Cryoballoon; Long-term follow-up; Pulmonary vein isolation.

Fig. 1

Study flow chart. CB2 second-generation 28 mm cryoballoon, PVI pulmonary vein isolation

Fig. 2

The Kaplan–Meier curve demonstrates the relative proportion of patients in stable sinus rhythm following index pulmonary vein isolation using the second-generation 28 mm cryoballoon during a follow-up period of 849 ± 74 (group 1) and 848 ± 101 days (group 2, p = 0.13). 69 % of patients (group 1) and 67 % of patients (group 2) remained in stable sinus rhythm during the follow-up period (p = 0.69)

Fig. 3

Location of electrical reconduction gaps. The figure depicts the number and location of reconduction gaps identified during re-ablation procedures. a Findings for group 1 (bonus-freeze protocol), b findings for group 2 (no bonus-freeze protocol). Septal and lateral pulmonary vein ostia are divided into four segments (antero-superior, antero-inferior, postero-superior, postero-inferior). Numbers express reconduction gaps found for each segment. No gaps were found along the carina between the ipsilateral pulmonary veins. Data for a single left common pulmonary vein is not shown (each group n = 1 single left common pulmonary vein, each with one gap. RSPV right superior pulmonary vein, RIPV right inferior pulmonary vein, LSPV left superior pulmonary vein, LIPV left inferior pulmonary vein)