The novel POLARx ablation system improves cryothermal single-shot guided pulmonary vein isolation: impact of individual pulmonary vein anatomy

Abstract Funding Acknowledgements Type of funding sources: None. Background Cryoballoon (CB)-guided pulmonary vein isolation (PVI) is an established treatment for atrial fibrillation (AF). Recently, a novel balloon-guided cryothermal single shot device (POLARx) was introduced. Purpose This observational study aimed to evaluate ablation efficacy and outcome using the novel POLARx CB system compared to the established one and to access the impact of individual PV characteristics on freedom from arrhythmia recurrence in paroxysmal (PAF) and persistent (PERS) AF. Methods 666 patients undergoing CB-guided ablation for AF were included. 601 patients treated with the AFA ablation system (Arctic Front Advance Pro, AFA) were compared to 65 consecutive patients who underwent PVI using the POLARx. Individual anatomical characteristics of the left atrium and PVs were assessed using pre-procedural cardiac magnetic resonance imaging (MRI). For each PV, the cross-sectional orifice area (CSOA) was determined. Follow-up examinations were scheduled after 3 and 6 months. Results Acute PVI was achieved in all patients (100%). 6-months AF-free survival was significantly higher in the POLARx cohort (POLARx: n=45, 69%; AFA: n=359, 60%; Log-rank p=0.037*). This applies to PAF (n=42, 65%, p=0.033*), PERS (n=23, 35%, p<0.001*) and normal PV anatomy (2 left- and two right-sided PVs; n=57, 88%, p< 0.001*). MRI found a comparable percentage of patients with normal PV anatomy (POLARx: n=57, 88%; AFA: n=512, 85%, p=0.126). A higher amount of variant PV anatomy was revealed in patients with PERS AF (p=0.043*), but this factor was not predictive for AF-recurrence (PAF: p=0.610; PERS: p=0.096). PAF patients with AF-recurrence presented with significantly larger CSOA of the left sided PVs and the right superior PVs (LSPV: 224.8 ± 98.1 mm2 vs. 220.6 ± 64.8 mm2, p<0.001*; LIPV: 145.9 ± 63.2 mm2 vs. 140.4 ± 52.8 mm2, p<0.001*; RSPV 268.9 ± 79.3 mm2 vs. 262.3 ± 75.6 mm2, p<0.001*). In patients with PERS AF no association between CSOA and ablation outcome was observed. Multivariate Cox regression analyses identified the AFA ablation system (p=0.022*, hazard ratio (HR) 1.776, confidence interval (CI) 0.240-9.281) and PERS AF (p<0.001*, HR 6.608, CI 0.220-73.839) as independent predictors for AF-recurrence. Conclusion PVI using the POLARx system improves freedom from AF recurrence independent of individual anatomical considerations and PV occlusion rates. For PAF patients, a significant association between CSOA and the outcome after CB- guided PVI was demonstrated.