Mitral Regurgitation (MR) is the most prevalent type of valvular heart disease in clinical practice, with an average prevalence of approximately 1% in populations with moderate-to-severe or worse MR, which increases significantly with age. Functional MR (FMR) is one subtype of MR and can be further classified into atrial FMR, ventricular FMR, and mixed FMR based on its underlying mechanisms. Pathophysiologically, FMR is closely associated with atrial fibrillation (AF) and heart failure (HF). Studies suggest that catheter ablation for AF may improve FMR in some patients and reverse left atrial (LA) and left ventricular (LV) remodeling. However, there is currently a lack of precise and effective indicators or predictive models to determine the evolution of FMR after AF ablation in both domestic and international research.

This study aims to conduct a multicenter prospective cohort study, enrolling patients with moderate or worse FMR and persistent AF undergoing ablation. Using postoperative 3-month FMR improvement as the primary outcome, we will employ big data mining and multimodal analysis to construct a predictive model for FMR progression after AF ablation and validate it through prospective multicenter testing. The findings will provide a scientific basis for clinical decision-making and precision medicine in this patient population.

Inclusion Criteria:

1. Aged 18-75 years
2. Diagnosis of functional mitral regurgitation (FMR) by transthoracic echocardiography (TTE) and/or transesophageal echocardiography (TEE) with combined qualitative and quantitative assessment, demonstrating moderate or worse regurgitation (≥ grade 2+)
3. Persistent atrial fibrillation (AF) with successful catheter ablation
4. Signed informed consent with commitment to regular follow-up for ≥1 year

Exclusion Criteria:

1. Acute or chronic degenerative mitral regurgitation (DMR) from any etiology
2. Paroxysmal or permanent atrial fibrillation
3. Planned repeat ablation for AF recurrence
4. Concomitant moderate/severe valvular disease (e.g., mitral stenosis, aortic stenosis/regurgitation, pulmonary stenosis/regurgitation)
5. Prior valvular surgery/intervention
6. History of open-heart surgery
7. Severe pulmonary hypertension (PASP >70 mmHg) refractory to medical therapy
8. Left atrial diameter ≥60 mm (diastolic phase) on echocardiography
9. Uncontrolled hyperthyroidism
10. Intracardiac mass/thrombus/vegetation
11. Significant shunts (ASD/VSD/PDA)
12. Hypertrophic obstructive cardiomyopathy
13. Active severe infection/sepsis (including infective endocarditis)
14. Scheduled CRT/CRT-D/CCM implantation
15. Untreated critical CAD (e.g., ≥70% stenosis in proximal/mid LAD/LCX/RCA requiring revascularization) or concomitant major cardiovascular surgery needs
16. End-stage heart failure (ACC/AHA Stage D) requiring mechanical support/transplant listing
17. Severe hepatic dysfunction (acute liver failure/decompensated cirrhosis, Child-Pugh C)
18. Severe renal impairment (CKD 5: eGFR<15 mL/min or dialysis)
19. Hemodynamic instability (SBP<90 mmHg/MAP<70 mmHg with hypoperfusion [urine output<30 mL/h])
20. Contraindications to antithrombotics: Active bleeding (GI/intracranial/visceral), bleeding disorders (hemophilia/ITP/leukemia etc.), severe hematologic abnormalities (platelets<20×10⁹/L, spontaneous INR>3)
21. Uncontrolled autoimmune/connective tissue disease
22. Acute MI within 4 weeks
23. Stroke within 30 days
24. Acute peptic ulcer/upper GI bleeding within 3 months
25. Pregnancy/lactation
26. Declined informed consent
27. Life expectancy <1 year
28. Poor compliance (anticipated inability to complete follow-up)
29. Concurrent participation in conflicting clinical trials
30. Other investigator-determined exclusions.

Patients with moderate-to-severe functional mitral regurgitation (FMR) and persistent atrial fibrillation undergoing catheter ablation