Safety and Effectiveness Study of Dragonfly System for Degenerative Mitral Regurgitation

Inclusion Criteria: 1. Age ≥ 18 yrs. 2. Symptomatic moderate-to-severe (3+) or severe (4+) mitral valve regurgitation (DMR) confirmed by transthoracic echocardiography. 3. NYHA functional class II, III, IV. 4. Left ventricular ejection fraction (LVEF) ≥ 20%. 5. Anatomically suitable for transcatheter mitral valve repair by edge-to-edge technique, and can be treated by the DragonflyTM device, as assessed by the site investigators and confirmed by the echo core laboratory and eligibility committee. 6. High surgical risk as defined by either Society for Thoracic Surgery Risk Calculator score for valve replacement ≥ 8 points; or STS score for valve repair ≥ 6 points; or other high surgical risks. e.g. presence of ≥2 moderate to severe frailty factors; or the presence of possible surgical obstacles; or the presence of ≥2 major organ dysfunctions that could not be improved after surgery; or other surgical high-risk factors as determined by the local heart team. 7. Transseptal catheterization and femoral vein access is determined to be feasible. 8. The subject or subject's legal representative has been informed of the nature of the trial, willing to accept the experimental tests, and has provided written informed consent. Exclusion Criteria: 1. Echocardiographic evidence of intra-cardiac mass, thrombus, or vegetation. 2. The presence of other severe heart valve disease requiring surgical intervention. 3. Prior mitral valve leaflet surgery or transcatheter mitral valve intervention. 4. Estimated pulmonary artery systolic pressure (PASP) \> 70 mm Hg assessed by echocardiography. 5. History of acute myocardial infarction in the prior 4 weeks or untreated clinically significant coronary artery disease requiring revascularization. 6. Any percutaneous cardiac intervention within the 30 days, or any cardiac surgery within the 6 months prior to randomization; or if, in the judgment of the investigator, the subject's femoral vein is unable to accommodate a 25F catheter or has an ipsilateral deep venous thrombosis; or the anatomy is not accessible for transseptal puncture. 7. Subjects in whom transesophageal echocardiography (TEE) or general anesthesia is contraindicated. 8. End-stage heart failure (ACC/AHA stage D), or prior orthotopic heart transplantation, or on the waiting list for a heart transplantation. 9. Active endocarditis, or active rheumatic heart disease, or leaflets degenerated from either endocarditis or rheumatic disease. 10. Cerebrovascular accident within 30 days prior to randomization or symptomatic severe carotid stenosis (\> 70% by ultrasound). 11. Evidence of acute peptic ulcer or gastrointestinal hemorrhage in the prior 3 months. 12. Hemorrhagic or coagulopathic disorders, contraindications to antithrombotic medication. 13. Modified Rankin Scale ≥4. 14. The subjects suffer from diseases which may lead difficulty in evaluating treatment (e.g., cancer, severe metabolic disease, psychosis, etc.); 15. Pregnant or breastfeeding women. 16. Hemodynamic instability defined as systolic pressure \< 90 mmHg without afterload reduction, cardiogenic shock, or the need for inotropic support or an intra-aortic balloon pump. 17. Active infections requiring antibiotic therapy (in the case of temporary illness, antibiotics must be discontinued for at least 14 days before the subject can be enrolled). 18. Currently participating in an investigational drug or another device study that has not completed its primary endpoints or would clinically interfere with the endpoint of this study. Note: Trials requiring extended follow-up for products that were investigational, but have since become commercially available, are not considered investigational trials. 19. In the judgment of the investigator, subjects may not complete the trial according to poor compliance or in other circumstances when the investigator determines that the subject is unfit to participate in the study.