• Severe mitral valve regurgitation ≥ 3+ (moderate-to-severe mitral regurgitation disease);

• Patients with high or prohibitive risk for conventional open thoracic surgery as defined by STS risk scoring result; subjects who are judged as not tolerating mitral valve surgery due to STS procedural mortality risk ≥ 8% for mitral valve replacement or presence of any of the following risk factors:

‣ Porcelain aorta or active ascending aortic atheroma

⁃ Prior radiation therapy to mediastinum

⁃ History of mediastinitis

⁃ Left ventricular ejection fraction (LVEF) \< 40%

⁃ Presence of unobstructed coronary artery bypass graft

⁃ History of 2 or more cardiothoracic surgeries

⁃ Liver cirrhosis

⁃ Other surgical risk factors

• Degenerated MR patients, or functional MR patients who have received guideline-directed medical therapy (GDMT therapy)

• Age ≥ 18 years, male or female;

• Patients who are at extremely high risk or not suitable for conventional mitral valve surgery, as assessed by a multidisciplinary heart team (including at least one cardiac surgeon and one cardiologist);

• Anatomically suitable for transcatheter mitral valve repair by edge-to-edge technique and can be treated by the SQ-Kyrin device;

• Patients who can understand the objectives of the trial, volunteer to participate in the study, sign the informed consent form, and are willing to receive related examinations and clinical follow-up.