Background: Pulmonary vein (PV) isolation improves outcomes in atrial fibrillation (AF), but its efficacy is reduced in persistent AF, with higher recurrence rates, particularly in females. Identifying non-PV ablation targets requires improved understanding of structural substrates such as fibrosis. While right atrial (RA) drivers have been reported in persistent AF, the role of fibrosis in ablation outcomes remains unclear. This study investigates spatial differences in RA fibrosis associated with AF recurrence and sex.
Methods: RA geometries were reconstructed from pre-ablation gadolinium-enhanced MRI in 53 AF patients (67 ± 10 years; 23 females; 21 with recurrence). Fibrosis was defined from signal intensity. A structural pipeline quantified volumetric spatial distributions of fibrosis. Geometries were normalised using anatomical landmarks, geodesic distances, and Laplace-based parameterisation, then averaged within subgroups (recurrence vs non-recurrence; male vs female) for comparison.
Results: Patients with AF recurrence showed increased fibrosis in the septal wall and reduced fibrosis in the lateral wall compared to non-recurrence cases. Fibrosis patterns in recurrence cases were more spatially consistent, whereas non-recurrence cases exhibited greater variability. Sex-specific differences were observed: males had more fibrosis in the right atrial appendage, while females showed greater fibrosis near the inferior vena cava. Notably, females and recurrence cases shared similar fibrosis distributions.
Conclusion: RA fibrosis exhibits distinct spatial patterns associated with AF recurrence and sex. These findings suggest that fibrosis distribution may contribute to recurrence risk and could inform patient-specific ablation strategies.