To confirm the effectiveness and safety of the Dragonfly transcatheter mitral valve repair system for the treatment of chronic moderate to severe (3+) or severe (4+) functional mitral regurgitation (FMR) who remained clinically symptomatic after adequate treatment.

This study is a prospective, multicenter, randomized controlled design. Patients are chronic moderate to severe (3+) or severe (4+) functional mitral regurgitation (FMR) who remained clinically symptomatic after guideline-directed medical treatment. After signing an informed consent form, subjects in the experimental group will undergo the transcatheter mitral valve repair procedure using the DragonFly™ Transcatheter Mitral Valve Clip System . According to the investigator's discretion, all subjects in the treatment group will continue to receive maximally tolerated guideline-directed medical therapy (GDMT). Subjects in the control group will also continue maximally tolerated GDMT as determined by the investigator. After completing the 12-month follow-up, crossover to the treatment group will be permitted.

All subjects were followed up before discharge (excluding the control group), and 30 days, 6 months, 12 months, and 24 months after treatment. Subjects in the experimental group and those who crossed over to the experimental group underwent extended clinical follow-up for 3, 4, and 5 years.

Inclusion Criteria:

1) Age ≥ 18 yrs. 2) Symptomatic functional mitral regurgitation (FMR) (≥3+) due to ischemic or non-ischemic cardiomyopathy

• Transseptal catheterization and femoral vein access is determined to be feasible.
• 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 intracardiac mass, thrombus, or vegetation. 2）Echocardiography revealed severe restriction of leaflet motion due to tethering.

3) The presence of other severe heart valve disease requiring surgical intervention.

• 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.
• 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.