Abstract Body (Do not enter title and authors here): Background:
The effects of Mineralocorticoid receptor antagonist (MRAs) on atrial fibrillation (AFib) outcomes following catheter ablation in patients with heart failure with preserved ejection fraction (HFpEF) is not well described.

Objective:
This study sought to assess the impact of MRAs on AFib catheter ablation outcomes among patients with HFpEF.

Methods:
We conducted a retrospective cohort study using the TriNetX research network, we identified, patients ≥18 years of age with HFpEF who had undergone AF ablation up to December 1, 2024 by means of CPT and ICD-10 codes. Patients were stratified based on the baseline MRAs use. Propensity score matching was performed to balance baseline characteristics between MRA users and non-users. The primary outcome was the risk of re-do AF ablation after a blanking period of the index ablation.

Results:
The study included 6,828 propensity-matched patients in each cohort. MRA use in patients with HFpEF undergoing AF ablation was associated with a non-significant trend toward a higher risk of redo AF ablation (OR: 1.11; 95% CI: 1.00–1.23; p = 0.05). This was accompanied by a modest yet statistically significant increase in rates of cardioversion (OR: 1.17; 95% CI: 1.07–1.27; p < 0.001) and new antiarrhythmic drug use (OR: 1.15; 95% CI: 1.07–1.23; p < 0.001). Additionally, MRA use in this group was not protective against acute HFpEF exacerbation and was linked to an increased odd of stroke.

Conclusion:
This retrospective analysis suggests that MRA use in patients with HFpEF undergoing AFib ablation may not be associated with a meaningful reduction in re-do ablation rates or improved event-free survival. Furthermore, MRA use was associated with a modestly higher burden of arrhythmia recurrence, as reflected by increased cardioversion rates and the need for new antiarrhythmic drug therapy. While our results suggest that MRAs may not confer a clear advantage in reducing arrhythmia recurrence or improving procedural outcomes, their clinical utility in this setting remains uncertain.