Impact of left atrial anatomy on acute and long-term pulmonary vein isolation

The left atrial anatomy plays an important role in determining the success of balloon-based pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF). The introduction of a second cryoballoon (CB) system necessitates validation of both established and potential new predictors based on preprocedural imaging of procedural success.

To determine whether left atrial anatomical features can predict first-pass pulmonary vein isolation and the recurrence of atrial tachycardia for both CB systems.

We retrospectively analysed patients from the randomized COMPARE CRYO study, investigating the efficacy and safety of the PolarX (PolarX-group) compared to the established Arctic Front cryoballoon system (AFA-group) for PVI in patients with paroxysmal AF. After segmentation and 3D reconstruction of the pre-procedural imaging, various selected anatomical features were extracted (Figure 1). Acute, first-pass isolation was defined as PVI after the first ablation. Regression analysis was performed to identify predictors for first-pass success and long-term recurrence within 12 months of follow-up.

A total of 191 patients were analysed. The baseline parameters and measured anatomical variables were not different between both groups. First-pass vein isolation was achieved in 69.0 % and 67.8% of veins for the AFA- and PolarX-group, respectively. A significantly higher first-pass isolation rate was observed for the left inferior PV (LIPV) in the PolarX-group (77% vs 63%, p=0.03) and for the right superior PV (RSPV) in the AFA-group (92% vs 79%, p=0.01). Among all baseline parameters, only female sex was associated with an impaired first-pass isolation of the RSPV (OR: 0.50 [95% CI: 0.26-0.97]; p = 0.04). In a per-vein analysis, the absence of an orthogonal-isocentric orientation (OIO) of the left superior PV was observed as predictor for first-pass failure for the PolarX catheter (OR 0.08; CI% 0.008-0.833, p=0.035). The absence of an OIO was significantly associated with recurrence of any atrial tachyarrhythmia during follow-up for both CB systems.

Difference for first-pass isolation between the CB systems were observed for the LIPV and RSPV. However, OIO was the only prespecified anatomical feature identified to predict likelihood for first-pass PVI. Although anatomical factors alone may not fully predict PVI success, our findings suggest that a personalized approach, carefully considering anatomical features, may optimize treatment outcomes. Further research is needed to validate these findings.