Long-term impact of a bonus freeze on clinical outcome: Analysis of effective and non-effective bonus freezes in cryoballoon ablation

Single-shot technique of cryoablation for atrial fibrillation has comparable effective and safety outcomes compared to standard technique: insights from multiple clinical studies

Background

Although there are many freezing protocols available, the optimal freezing dose is still not determined. We aimed to evaluate the effectiveness and safety of different freeze strategies of CBA in the treatment of AF.

Methods

PubMed, Cochrane Library, Web of Science, and Embase were searched up to 1st December 2022. Studies comparing the outcomes between single-shot technique and standard technique of cryoablation were included. Subgroup analysis identified potential determinants for single-shot technique procedure.

Results

Our search resulted in 3407 records after deduplication. A total of 17 qualified studies met our inclusion criteria. Compared with standard technique, single-shot technique of cryoablation has a comparable rate of freedom from AF/AT(RR 1.00; P = 0.968), a trend for lower rate of procedure complications (RR 0.80; P = 0.069), a lower rate in transient phrenic paralysis (t-PNP) (RR 0.67; P = 0.038), a similar rate in persistent phrenic paralysis (per-PNP) (RR 1.15; P = 0.645), as well as a comparable procedure parameters. Importantly, potentially significant treatment covariable interactions in procedure complications were found in freeze strategy subgroup, male proportion subgroup and age subgroup, including single-shot freeze (RR 1.02; P = 0.915) and TTI-guided (RR 0.63; P = 0.007) with interaction P = 0.051, high male proportion (RR 0.54; P = 0.005) and a low male proportion (RR 0.94; P = 0.759) with interaction P = 0.074, as well as age ≥ 65 (RR0.91; P = 0.642) and age <65 (RR 0.54; P = 0.006),interaction P = 0.090. Meanwhile, only one significant treatment covariable interactions in procedure complications was found in the hypertension subgroup, including HT > 60% (RR 0.89; P = 0.549) and HT ≤ 60% (RR 0. 46; P < 0.01) with interaction P = 0.043.

Conclusions

Our study suggested that single-shot technique of cryoablation has comparable effective and safety outcomes for AF ablation compared to standard technique.

Effectiveness and safety of a single freeze strategy of cryoballoon ablation of atrial fibrillation: an EHRA systematic review and meta-analysis

To conduct a systematic review and meta-analysis to compare the effectiveness and safety of cryoballoon ablation of atrial fibrillation (AF) performed using a single freeze strategy in comparison to an empiric double ('bonus') freeze strategy. We systematically searched MEDLINE, EMBASE, and CENTRAL databases from inception to 12 July 2020, for prospective and retrospective studies of patients undergoing cryoballoon for paroxysmal or persistent AF comparing a single vs. bonus freeze strategy. The main outcome was atrial arrhythmia-free survival and eligible studies required at least 12 months of follow-up; the primary safety outcome was a composite of all complications. Study quality was assessed using the Cochrane risk of bias tool and the Newcastle-Ottawa Scale. Thirteen studies (3 randomized controlled trials and 10 observational studies) comprising 3163 patients were eligible for inclusion (64% males, 71.5% paroxysmal AF, mean CHA2DS2-VASc score 1.3 ± 0.9). There was no significant difference in pooled effectiveness between single freeze strategy compared to double freeze strategy [relative risk (RR) 1.03; 95% confidence interval (CI): 0.98-1.07; I2 = 0%]. Single freeze procedures were associated with a significantly lower adverse event rate (RR 0.72; 95% CI: 0.53-0.98; I2 = 0%) and shorter average procedure time (90 ± 27 min vs. 121 ± 36 min, P < 0.001). A trend for lower risk of persistent phrenic nerve palsy was observed (RR 0.61; 95% CI: 0.37-1.01; I2 = 0%). The quality of included studies was moderate/good, with no evidence of significant publication bias. Single freeze strategy for cryoballoon of AF is as effective as an empiric double ('bonus') freeze strategy while appearing safer and probably quicker (PROSPERO registration number CRD42020158696).