Meta-Analysis of Atrial Fibrillation Ablation Strategies
How different is the efficacy and procedural duration of atrial fibrillation ablation with irrigated radiofrequency (IRF) versus duty-cycled phased radiofrequency (PRF) versus cryoballoon ablation (CBA)?
The authors searched published literature and performed both traditional frequentist meta-analysis (comparing only two strategies at a time) and network meta-analysis (comparing all three strategies at once). Both randomized and matched cohort studies were allowed.
A total of 31 studies were included in the analysis, encompassing 7,839 patients. There were three randomized trials and 11 observational studies comparing PRF versus IRF; there were three randomized trials and 13 observational studies comparing CBA versus IRF. One randomized study directly compared PRF versus CBA. Direct traditional meta-analysis using all studies showed that PRF was associated with higher freedom from AF compared to IRF (66% vs. 58%), while CBA was comparable with IRF (65% vs. 62%). PRF was associated with shorter procedural time, while there was a trend toward shorter procedural time with CBA compared to IRF. Indirect network meta-analysis using all studies showed that PRF was associated with higher freedom from AF compared to CBA and IRF (odds ratio, 1.51) while having the shortest procedural time (-40.8 minutes). However, when the meta-analysis was repeated using randomized study data only, IRF and PRF were comparable in terms of freedom from AF over a mean follow-up of 9 months, and PRF was associated with significantly shorter procedural time. There was a higher freedom from AF with IRF compared to CBA over a mean follow-up of 12 months, while both techniques demonstrated similar procedural time.
There is insufficient evidence to suggest that one ablation modality is more efficacious than another. However, there was a consistent reduction in procedural duration associated with PRF.
Outcomes of the conventional IRF ablation have been modest. Newer technologies such as PRF and CBA have been developed to address this vexing problem as well as the notoriously long procedural duration. The authors of this report undertook a daunting task of comparing the efficacy of the three ablation technologies: two types of radiofrequency ablation and cryoablation. The analysis is fraught with many pitfalls including: 1) the rapidity with which the techniques of AF ablation have been evolving, 2) the use of additional lines (roof, mitral, etc.) in some studies while not in others, 3) heterogeneity of AF types (paroxysmal, persistent, long-standing persistent) with and without significant structural heart disease (which affects outcomes a great deal), 4) preponderance of nonrandomized studies, 5) lack of standardized outcome measures pervasive in much of the published literature, and 6) so much more. On the other hand, procedure duration is straightforward to compare, and shows that PRF offers the advantage of shorter procedural duration.
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