Ablation lesion formation after PVI with cryoballoon versus CLOSE-guided RF ablation assessed by late gadolinium enhancement CMR

Abstract Background Durable pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) ablation. Technological advances like ablation index-guided RF ablation and second generation cryoballoon have substantially improved lesion durability, but PV reconnection remains a key determinant of AF recurrences. Purpose We aimed to compare RF ablation following the CLOSE protocol and latest cryoballoon ablation regarding lesion continuity and durability using late gadolinium enhancement (LGE) CMR. Methods This study was based on a prospective registry in which all patients receive an LGE-CMR at 3 months after AF ablation. LGE-CMRs from consecutive patients that had undergone first-time PVI-only AF ablation, either by CLOSE-guided RF ablation (CLOSE) or cryo-ablation with the arctic front advance balloon (CRYO) were analysed. Gradient echo MR sequences were acquired in sinus rhythm and 3D-reconstruction of left atrium and PVs performed using ADAS-3D software. LGE was quantified based on the signal intensity ratio of each voxel relative to the blood pool, applying a previously validated threshold of >1.2 to define LGE indicative of ablation-induced scarring. LGE discontinuations of >3 mm were considered as gaps, and complete lesions were defined as LGE covering >90% of the peri-antral circumference of ipsilateral PV pairs. The analysis included an assessment of the average number of gaps around PV ostia, the normalized gap length, which was calculated as a percentage of the total gap length and the total PV perimeter. The ablation lesion width was also measured in millimetres. Results Post-ablation LGE-CMR from 87 patients were analysed - 40 patients in the CRYO group (70% paroxysmal AF), 47 in the CLOSE group (47% paroxysmal AF). The post-ablation LGE-lesions encircling ipsilateral PVs covered 74% (CRYO) and 75% (CLOSE) of the peri-antral circumference, obtaining no significant difference in the normalized gap length (26.23% vs 24.74%, p=0.7 ), as presented in figure 1c. Although LGE lesions were significantly wider in the CRYO group (9.33 vs 7.11 mm, p<0.001) as presented in figure 1a and figure 1b; the proportion of PVs with complete circumferential LGE lesions was higher with CLOSE-guided RF ablation (39% vs. 24%, p=0.034). However, the total number of gaps per patient was similar in both groups (2.7 vs 3.2, p=0.16). Of note, in both groups, detectable gaps were more frequent in right vs. left PVs (1.98 vs 1.08, p<0.001). Finally, 12-months arrhythmia-free survival rates did not differ significantly (CRYO 60.0% vs. CLOSE 72.4%; p=0.26), albeit it has to be considered that the study was not powered to detect subtle or moderate between-group differences in clinical endpoints. Conclusion While ablation lesions are significantly wider with cryoballoon ablation, lesions continuity may be better with CLOSE-guided RF ablation.Segmentation and Box plot of RF and CRYO