Atrial fibrillation first? Investigating rhythm control in de novo high-grade functional mitral regurgitation and atrial fibrillation.

Background: Atrial fibrillation (AF) and functional mitral regurgitation (FMR) frequently coexist, presenting significant challenges for therapeutic management. Current evidence offers limited direction on the prioritization of treatment for these conditions. This study aims to evaluate the impact of rhythm control on high-grade FMR and identify predictors of persistent high-grade FMR after AF treatment.

Methods: This single-center study analyzed patients with newly diagnosed AF and concomitant high-grade FMR. Predictors of persistent high-grade FMR after rhythm control of AF were assessed by logistic regression.

Results: Among 795 patients hospitalized with new-onset AF, 14% (111/795) were diagnosed with high-grade FMR. Rhythm control successfully restored sinus rhythm in 86.3% of cases. FMR severity improved in 58.8% of patients, effectively eliminating the need for further interventions in these cases. Independent baseline predictors of persistent high-grade FMR at follow-up included New York Heart Association (NYHA) class IV heart failure symptoms, mean pulmonary artery pressure (mPAP) > 20 mmHg, effective regurgitant orifice area (EROA) > 0.4 cm², vena contracta > 8 mm, and left atrial volume index (LAVI) > 48 mL/m².

Conclusions: Rhythm control of AF significantly reduced the severity of FMR in most patients, eliminating the need for mitral valve (MV) intervention in these cases. The identified predictors of persistent high-grade FMR could contribute to refined risk assessment and assist in treatment decision-making, potentially supporting early referral for MV intervention in appropriate patients.