What makes pulmonary vein anatomy important and preprocedural imaging useful during catheter ablation for atrial fibrillation?

In a recent paper, Khoueiry et al.1 reported that pulmonary vein isolation (PVI) by either radiofrequency or cryoballoon techniques for paroxysmal atrial fibrillation (AF) ablation showed similar efficacy and safety profile at mid-term follow-up and pulmonary vein (PV) anatomy demonstrated no impact on outcomes. Thus, the authors proposed that the consideration of PV anatomical criteria is probably not mandatory when selecting paroxysmal AF patients for cryoballoon ablation. Currently, because of the triggering electrophysiological activity of muscular sleeves around the conjunctional points of left atrium and PVs, PVI is accepted as the standard approach during AF ablation therapy.2 Several technological tools and techniques are used for PVI with various efficacy and safety results. Current approaches are mainly targeting the antral region of PVs or atriovenous junction points. The anatomy of PVs may demonstrate a significant variation in between healthy subjects and patients with AF.3 As mentioned by Khoueiry et al.,1 previous study results were conflicting with regard to the impact of PV variation on catheter ablation outcomes. However, the presence of PV anatomical variation is expected to complicate ablation procedure during cryoballoon technique because of the current recommendation for the use of ‘single-big cryoballoon’ approach. Therefore, detailed PV anatomy should be assessed before deciding on the ablation technique. Contrarily, Khoueiry et al.1 reported no difference in regard to efficacy and safety outcomes in between cryoballoon and radiofrequency techniques. However, detailed anatomical evaluation of PVs has not been included in this study such as PV orientation, PV ostium ovality index, frontal angle of PVs, and size of each PVs, which were shown to be independent predictors of AF recurrence in previous studies.4,5 Furthermore, a common anatomical finding such as LA roof pouch or diverticulum that was reported to be associated with recurrence after catheter ablation has not been mentioned in this paper. I thought that a detailed assessment of PV anatomy rather than number of PVs alone may have significant impact on the selection of ablation technique before procedure. According to our (Hacettepe University, Ankara, Turkey) experience with cryoballoon-based AF ablation (known as a high-volume centre for cryoablation), extreme tips either too small or too large for PV size and larger common ostium are found as significant drawbacks for good occlusion, circumferential tissue contact, and lesion formation. Furthermore, occlusion of each sub-branches in case of common ostium may not be enough to achieve complete isolation of PVs from atrium. Thus, preprocedural imaging by computerized tomography (CT) or magnetic resonance imaging (MRI) may help us in the selection of ablation technique and tools. Furthermore, preprocedural imaging may also guide us to avoid significant complications such as phrenic nerve injury.6 Therefore, the authors in this paper may comment on the detailed features of PV anatomy and their impact on the efficacy of ablation as mentioned above and the important contributions to the safety issues. Conflict of interest: none declared.