To evaluate the improvement of mitral regurgitation after catheter ablation of atrial fibrillation or regular drug therapy in atrial fibrillation patients combined with atrial functional mitral regurgitation.

Atrial fibrillation results in the loss of the atria's normal contracting ability, leading to blood stasis within the left atrium and its subsequent enlargement. This condition can progress to cause dilation of the mitral annulus and mitral regurgitation-a phenomenon referred to as functional mitral regurgitation (FMR). Atrial functional mitral regurgitation (AFMR), triggered by the enlargement of the left atrium and remodeling of the mitral annulus, has increasingly become a focal point of research in recent times. Past studies have indicated that in patients who revert to and maintain sinus rhythm following catheter ablation for atrial fibrillation, there is a notable reduction in the size of the left atrium, the diameter of the mitral annulus, and the severity of mitral regurgitation. This suggests that patients with AFMR may derive significant benefits from the restoration of sinus rhythm. This investigation constitutes a prospective, multicenter cohort study. Eligible patients diagnosed with atrial fibrillation accompanied by atrial functional mitral regurgitation, who meet the inclusion criteria and do not fulfill the exclusion criteria, are being recruited. Depending on clinical judgment or patient preference, participants are assigned to receive either catheter ablation for atrial fibrillation or standard medical therapy, with the aim of assessing the impact of these different treatments on alleviating the degree of mitral regurgitation. The study aims to enroll 500 patients, with follow-up assessments scheduled at 3-month, 6-month, and 12-month intervals following enrollment.

Inclusion Criteria:

1. Patients aged 18 to 80 years old;
2. Patients diagnosed with symptomatic paroxysmal atrial fibrillation (AF history < 5 years)
3. Moderate to severe MR and normal LV ejection fraction (≥50%), LVEDD<55 mm, and normal LV wall systolic function
4. Able to understand the purpose of the trial, participate in the trial voluntarily with informed consent form signed by the subject him/herself or his or her legal representative, and willing to complete follow-up visits as required under the protocol

Exclusion Criteria:

1. Atrial fibrillation secondary to electrolyte imbalances, thyroid disease or other reversible factors
2. Active endocarditis or active rheumatic heart disease, or degenerative mitral regurgitation due to endocarditis or rheumatic valvular heart disease
3. Moderate to severe mitral stenosis
4. Imaging examination shows left atrium or left atrial appendage thrombosis
5. Left ventricular ejection fraction less than 50%
6. Left atrial diameter more than 50mm
7. Patients with previous left atrial appendage occlusion or left atrial appendage closure, patent foramen ovale closure, atrial septal defect closure or repair (only applied for patients who need to ablation)
8. Patients who have implanted devices such as implantable cardioverter defibrillator(ICD), cardiac resynchronization therapy(CRT) or pacemaker
9. Previous metal artificial valve or valve repair device implantation (only applied for patients who need to ablation)
10. Presence of lateral thrombus, tumors or other abnormalities that interfere with vascular puncture or catheter operation (only applied for patients who need to ablation)
11. Anticoagulation contraindications, and history of blood clotting or bleeding abnormalities
12. Acute systemic infection
13. Female patients who are pregnant, lactating, or unable to use contraception during the study
14. Patients' life expectancy is less than 12 months
15. Abnormalities or diseases that the investigator believes should be excluded from the scope of enrollment in this study

Atrial fibrillation combined with atrial functional mitral regurgitation