Right atrial remodeling after pulmonary vein isolation: analyzing changes in volume and function using cardiac MRI

Abstract Background Pulmonary vein isolation (PVI) using radiofrequency (RF) ablation is an established treatment for atrial fibrillation (AF). While a successful PVI in AF patients is known to promote reverse left atrial (LA) remodeling, the impact of PVI on right atrial (RA) remodeling remains poorly understood. Purpose To assess RA volumetric and functional remodeling parameters using cardiac magnetic resonance (CMR) imaging early (<72h) and late (3 months) after PVI. Methods Forty-three AF patients (74.4% male, 61±7 years) who underwent primo radiofrequency (RF) PVI, without prior or additional atrial flutter ablation, underwent three CMR scans: pre-PVI, early (<72 hours), and 3 months post-PVI. Atrial volumes and function were assessed using two- and four-chamber cine images, with atrial volumes indexed to body surface area (RAVImin, RAVImax, LAVImin, and LAVImax). Longitudinal atrial strain (reservoir, conduit, and contractile function) was analyzed using feature tracking (Circle CVI42). Results Early (<72h) post-PVI, RAVImin significantly decreased from 28.7 ± 10.3mL/m² to 26.0 ± 9.9mL/m² (p = 0.03), while RA EF demonstrated a significant increase (37.3 ± 11.5% to 41.7 ± 10.1%, p=0.03). At 3 months, both RAVImin and RAVImax showed significant further reductions compared to baseline (28.7 ± 10.3mL/m² to 24.8 ± 8.8mL/m², p=0.002; 45.2 ± 11.8mL/m² to 40.3 ± 11.9mL/m², p<0.001, respectively). During this period, RA functional improvement persisted, as evidenced by RA reservoir strain and RA contractile strain (16.2 ± 4.1% to 18.9 ± 3.6%, p=0.003; 6.6 ± 2.6% to 8.3 ± 2.8%, p=0.005, respectively) (Figure 1). LA volumes remained unchanged early post-PVI, but at 3 months, LAVImax significantly decreased compared to baseline (46.1 ± 13.0mL/m2 to 39.1 ± 11.3mL/m2, p<0.001). LA function, as assessed by reservoir and contractile strain, was significantly diminished early post-PVI (Table 1), and this reduction persisted at 3 months compared with baseline (18.6 ± 4.0% to 17.0 ± 3.4%, p=0.04; 8.5 ± 3.0% to 6.9 ± 2.4%, p<0.01, respectively). Conclusion This study demonstrates that RF PVI promotes reverse bi-atrial remodeling, with significant reductions observed in both RA and LA volumes, most likely due to reduced AF burden. LA function demonstrated a persistent impaired function at 3 months, while RA function improved following PVI. These findings suggest that although the reduction in AF burden may improve RA function and reduce atrial volumes, ablation-induced injury may contribute to a persistently reduced LA function.RA remodeling post-PVI RA and LA remodeling post-PVI