P1915Time to freeze - An updated meta-analysis on the efficacy and safety of cryoballoon versus radiofrequency ablation for atrial fibrillation
Authors: Fortuni F , Casula M , Sanzo A , Angelini F , Mugnai G , Rordorf R , De Ferrari G M 
Published: October 2019

Abstract

Background and aim
Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) ablation. Its efficacy to prevent recurrent arrhythmias in patients nonresponsive to antiarrhythmic drugs is proven. This procedure has a higher efficacy rate in patients with paroxysmal AF (PAF) compared with persistent AF (sustained AF - SAF). Radiofrequency (RF) ablation represents a standard of care for PVI, while, cryoballoon (CB) ablation has emerged as a valid alternative therapy. The aim of the present meta-analysis was to explore the comparative efficacy, and safety of CB compared with RF ablation for AF.

Methods
We searched PubMed and EMBASE for studies that investigated the comparative efficacy and safety of CB versus RF ablation for AF. The efficacy outcome was AF recurrence after the procedure. The safety outcomes were: incidence of pericardial effusion or cardiac tamponade, permanent phrenic nerve palsy, transient phrenic nerve palsy, vascular complications and major bleedings. The performance outcomes were: procedural time and fluoroscopy time. Random-effects Risk Ratios (RRs) were estimated using a DerSimonian-Laird model. Two subgroup sensitivity analyses were performed to stratify the result on the efficacy outcome according to type of AF (PAF versus SAF) and study design (randomized clinical trial (RCT) versus observational study (OS)).

Results
12 RCT and 34 OS were included in the analysis (n=13103). Mean follow-up was 14±6 months. 37 studies included only patients with PAF, while, 2 studies included only patients with SAF and the remaining 7 studies included both patients with SAF or PAF. Overall, CB ablation reduced the incidence of AF recurrence compared with RF ablation (RR 0.85; 95% CI 0.77–0.95; P=0.002 - Figure). However, this reduction was not consistent in the RCT subgroup (RR 0.90; 95% CI 0.72–1.13) and it was marginally non-significant in the SAF subgroup (RR 0.76; 95% CI 0.57–1.01). Regarding the safety outcomes, although CB had a significantly higher rate of transient nerve palsy compared with RF procedure (RR 7.46; 95% CI 4.67–11.90) this difference became non-significant when considering permanent phrenic nerve palsy (RR 1.24; 95% CI 0.66–2.34). Moreover, CB was related to a lower incidence of pericardial effusion or cardiac tamponade compared with RF (RR 0.51; 95% CI 0.37–0.69) and there was no significant difference in vascular complications or major bleedings between the two strategies. Focusing on performance outcomes, CB ablation had a shorter procedural time compared with RF (mean difference −20 minutes; 95% CI −30 to −10; P<0.001); whereas, there was no significant difference in fluoroscopy time between the two.
CB vs. RF in preventing AF recurrence

Conclusions
This large study level meta-analysis demonstrates that CB is at least as effective as RF ablation in preventing arrhythmic recurrence both in patients with PAF and SAF. Moreover, our study suggests that CB has a safer profile and shorter procedural time compared with RF ablation.