Cryoballoon-Induced Circumferential Pulmonary Vein Fibrosis, Assessed by Late Gadolinium-Enhancement Cardiac Magnetic Resonance Imaging, and Its Correlation with Clinical Atrial Fibrillation Recurrence

Figure 1. Cross-sectional short-axis views of PVs on post-ablation LGE MRI using the “double oblique” technique. For each PV, two orthogonal plane images are used to create its circular cross-sectional short-axis view. (PV are centered between the MRI orthogonal lines.) Each PV ostium was divided into four segments: anterior, posterior, roof, and floor. Based on the cross-sectional views of PV ostia, ablation-induced PV ostial fibrosis are categorized as complete circumferential fibrosis, sub-complete circumferential fibrosis with single “minor” gap defined as LGE gap ≤ 1/3 PV segment length, partial fibrosis with major gaps defined by as LGE gap > 1/3 segment length, or absent PV fibrosis. In this patient, both left PVs are fully encircled by LGE enhancement (seen as bold white lines), defined as complete PV circumferential fibrosis, while both right PVs have major gaps () and thus are defined as partial incomplete circumferential PV ostial fibrosis. The right PV gaps are marked () both on the orthogonal plane images and the cross-sectional view.

Figure 2. A typical patient with cryoballoon-induced complete/sub-complete circumferential fibrosis in all PVs. Shown are pre-ablation (A) and post-ablation (B) cross-sectional short-axis views of the four PVs revealing minimal PV ostial fibrosis at baseline, while at post AF ablation, there is a complete circumferential fibrosis around both left PVs and sub-complete circumferential fibrosis around both right PVs, with minimal gaps in the anterior segments of both veins (red dottedlines). (C,D) Cor-responding ADAS 3D LGE model images pre (C) and post (D) cryoballoon AF ablation showing minimal LA fibrosis at baseline, post-ablation complete circumferential fibrosis around both left PVs without any gaps, and sub-complete circumferential fibrosis around both right PVs due to minimal gaps at their anterior segments, corresponding with the original images analyses. The post-ablation fibrotic areas on ADAS are colored red, while PV gaps are seen as blue color. The arrows show the matching of the minor PV gaps around both right PVs between the original MRI cross-sectional views and the ADAS model images.

Figure 3. A typical patient with cryoballoon-induced partial incomplete circumferential fibrosis in both right PVs. Shown are pre-ablation (A) and post-ablation (B) cross-sectional short-axis views of the four PVs revealing minimal PV ostial fibrosis at baseline, while at post AF ablation, there is a complete circumferential fibrosis around both left PVs and partial incomplete circumferential fibrosis around both right PVs with major gaps in the roof and anterior segments of both veins (red dotted lines). (C,D) Corresponding ADAS 3D LGE model images pre (C) and post (D) cryoballoon AF ablation, showing minimal fibrosis at baseline (C). Post-ablation MRI (D) reveals a complete circumferential fibrosis around both left PVs (including the carinal view) and partial circumferential fibrosis of both right PVs due to major gaps in the anterior and roof segments of both RSPV (*) and RIPV (**), corresponding and matching with the gaps seen on the “raw data” short-axis views. Post-ablation fibrotic areas on ADAS are colored red. Notably, Figure 1 and Figure 3 both describe the same patient.

Figure 4. Kaplan–Meier (KM) survival without AF recurrence analysis according to presence or absence of major PV ostial gaps. The analysis shows absence of AF recurrence among the group without major PV gaps and a significant AF recurrence among the groups with major PV gaps. This KM analysis reinforces the significant correlation between presence of major PV ostial gaps and AF recurrence.

Figure 5. Correlation of post-index-ablation MRI to redo procedure electro-anatomic mapping (EAM): Major PV gaps around both right PVs (upper-posterior views, lower-anterior views). Post-index-ablation MRI cross-sectional short-axis views (“raw data” images) (A), post-index-ablation MRI ADAS 3D model (B), and redo procedure EAM (Ensite Precision system) (C) all show complete circumferential PV ostial fibrosis around the main branches of a left common PV (marked as LSPV and LIPV); presence of major gaps in RSPV anterior, inferior, and posterior walls (marked by red dotted lines); and almost absent ostial fibrosis around RIPV (red dotted lines). Good correlation was found between post-ablation MRI and redo EAM regarding PV ostial scar and major gap locations (marked by red dotted lines in both MRI and EAM images).

Figure 6. Correlation of post-index-ablation MRI to redo procedure electro-anatomic mapping (EAM): Circumferential PV ostial fibrosis around all PVs (upper-posterior views, lower-anterior views). Post-index-ablation MRI (A) shows a complete circumferential PV fibrosis around both left PVs and sub-complete circumferential fibrosis around both right PVs. Due to newly documented atypical AFL, the patient underwent redo ablation, which started with LA EAM (Carto system), revealing circumferential scars around all PV ostia (B). A good correlation found between post-index-ablation MRI and redo procedure EAM shown. Notably, Figure 2 and Figure 6 both describe the same patient.