Cryoballoon versus radiofrequency guided by ablation index for atrial fibrillation ablation: a retrospective propensity-matched study
Authors: Ribeiro Queiros P , Fonseca P , Almeida J , Silva G , Silva M , Teixeira R , Oliveira M , Goncalves H , Dias Ferreira N , Primo J , Fontes-Carvalho R 
Published: October 2021

Abstract

Background/Introduction
Radiofrequency (RF) and cryoballoon (CB) ablation are established techniques for the treatment of atrial fibrillation (AF). Randomized trials comparing both techniques show similar levels of success; however, studies comparing CB with RF guided by ablation index (AI) are lacking.

Purpose
To compare the treatment success of CB with RF guided by AI, in patients with paroxysmal or persistent AF undergoing their first ablation procedure.

Methods
Patients undergoing AF ablation between 2017 and 2019 were retrospectively analysed. Primary success outcome was freedom from recurrence (defined as any episode of AF, atrial flutter or atrial tachycardia lasting &gt;30 seconds and occurring after 91 days from ablation, or need for antiarrhythmic drugs (AAD), cardioversion or redo procedure). Secondary end-point was a composite of adverse cardiovascular outcomes (stroke/TIA, emergency room visit for AF, hospitalization for AF or cardiovascular death). Analysis was done before and after propensity score matching.

Results
A total of 316 patients were included. Mean age was 56.9±11.7 years. Sixty-two percent were male (n=196). Paroxysmal AF was present in 80.7% (n=255), with no difference between groups. RF was used in 57.9% (n=183) and CB in 42.1% (n=133), with isolation of all pulmonary veins accomplished in 95.9% (n=302), without differences between groups. Mean CHA2DS2-VASc score was 1.5±1.3, being higher in the RF group (1.7±1.3 vs 1.2±1.1; p=0.03); these patients were also older (mean age 58.1±12.0 vs. 55.17±11.0 years; p=0.007) and more likely to be in AF at the ablation (26.7% vs. 16.5%; p=0.006), have chronic kidney disease (40.2% vs. 23.2%; p=0.002), anaemia (11.8% vs. 2.7%; p&lt;0.001), moderate/severe mitral disease (17.5% vs. 7.4%; p=0.012) or history of atrial flutter (17.7% vs. 3.1%; p&lt;0.001). Patients in the CB group had a longer history of AF (3.8±3.5 vs. 3.0±2.9 years; p=0.041), received treatment with AAD more often (60.9% vs. 55.9%; p=0.049) and had longer follow-up time (889±397 vs. 601±239 days; p&lt;0.001). Mean freedom from recurrence was not significantly different between groups (1106 days for CB vs. 889 days for RF; p=0.793), and recurrence rates were also similar (27.8% for CB vs. 23.5% for RF; p=0.291); however, patients treated with CB were more likely to need a redo procedure (38.3% vs. 17.4%; p=0.025). There were no differences in the composite of adverse cardiovascular events or in individual outcomes. Propensity score matching was done, and 154 patients were matched 1:1 for each treatment group. Survival free from recurrence showed no differences (1060 days for CB vs. 864 days for RF; p=0.912), and neither did the recurrence rate. CB patients with recurrence were still more likely to need a redo procedure (37.9% vs. 11.1%; p=0.021).

Conclusion
RF and CB result in similar survival free from AF and AF recurrence; however, recurrence in CB seems more significant, leading to higher rates of redo procedures.

Funding Acknowledgement
Type of funding sources: Public hospital(s). Main funding source(s): Centro Hospitalar de Vila Nova de Gaia/Espinho