Right Atrial Cardiomyopathy Assessed by Late Gadolinium Enhancement Cardiac MRI Following Pulmonary Vein Isolation in...

Structural remodeling in atrial fibrillation (AF) affects both atria, but it remains unknown how reverse right atrial (RA) remodeling after pulmonary vein isolation (PVI) corresponds to tissue-level changes.

This study evaluated RA tissue changes before and post-PVI using 3D late gadolinium enhancement cardiac MRI (LGE-CMR).

AF patients (n=54, 62±7 years, 38 males) underwent PVI and LGE-CMR imaging at baseline and 3 months post-PVI, and one-year AF recurrence was assessed. Healthy volunteers served as controls (n=18, 45±14 years, 4 males). RA-LGE was quantified using image-intensity-ratio thresholds (>1.20:total LGE; 1.20-1.32:border-zone;>1.32:dense LGE), and RA volumes and strain were analyzed.

AF patients exhibited significantly higher RA-LGE levels (36.0[14.4-59.9]% vs. 8.3[4.2-12.5]%, p<0.001), larger volumes (RAVImax: 44.7±11.3mL/m² vs. 37.3±8.2mL/m², p=0.01), and lower emptying fraction (37.7±11.4% vs. 47.3±6.7%, p<0.001), compared with controls. Among AF patients, total, border-zone, and dense RA-LGE was similar at baseline and 3 months post-PVI. RA volumes decreased post-PVI (indexed 3D volume: 58.4±16.5mL/m² to 53.8±14.0mL/m², p<0.001), and RA reservoir strain increased compared to baseline (17.1±4.6% to 18.9±3.7%, p=0.03). Substantial interindividual variability in RA-LGE changes was observed: only patients with decreased RA-LGE post-PVI demonstrated reverse RA remodeling. Total RA LGE increased in patients with AF recurrence (n=21, 38.9%) and remained unchanged in those without recurrence.

Compared with healthy controls, AF patients exhibited more extensive RA-LGE, RA enlargement, and dysfunction, reflecting significant RA myopathy. In AF patients, average RA-LGE was similar after PVI, but RA volumes decreased and function improved. Notably, patients with reduced RA-LGE showed reverse remodeling, while those with increased LGE did not.