Abstract Body (Do not enter title and authors here): Introduction: Atrial Fibrillation (AF) and Mitral Regurgitation (MR) share a bidirectional association, and AF is highly prevalent among MR patients. Transcatheter Edge to Edge Repair (TEER) for mitral valve (MV) is offered in severely symptomatic patients. The influence of pre-procedural AF on TEER outcomes is poorly defined.

Hypothesis: We hypothesized that patients with AF undergoing TEER for MR would have higher rates of hospitalizations and mortality compared to those without a diagnosis of AF.

Methods: We performed a retrospective single-center study where we identified 126 patients who underwent TEER for MR between January 2021 and December 2023. We then stratified the patients into two groups based on documented history of AF: No AF (n=53), AF (n=73). We then performed descriptive and comparative analyses of demographics, pre- and post-procedural echocardiographic parameters for 1 year. The primary outcomes were rates of heart failure (HF) hospitalizations and mortality.

Results: Mean age in the AF group was higher at 79 years compared to 76.16 years (p=0.0448). AF population also has a significantly higher incidence of hypertension, chronic kidney disease, and obstructive sleep apnea (OSA). Pre-TEER MV mean gradient was higher in the No AF group (3.045 + 1.49 vs 2.43 + 1.46, p = 0.0315). RA Area is higher in the AF group pre-TEER. While at 1 year, LAVI and RA Area were significantly higher in the AF group. HF hospitalization rates were 17% in the no AF group while in the AF group it was 23.3%, p=0.186. Mortality in the AF group was significantly higher at 28.8% compared to 9.4% in the No AF group, with p=0.0076.

Conclusion: Our study showed a significant increase in mortality in the AF group despite similar symptomatic and echocardiographic improvements in both cohorts. Although HF hospitalization rates did not differ significantly, the presence of AF is associated with higher mortality in 1 year. Our findings highlight the importance of aggressive AF management and aim to maintain sinus rhythm post-procedure.