To evaluate second stage safety and feasibility of Mitral Loop Cerclage(MLC) Annuloplasty with CSTV for repair of functional mitral regurgitation.

The objective of this prospective, single-center, open label, feasibility test is to assess the safety and efficacy of Mitral Loop Cerclage Annuloplasty with CSTV protective device, in treating functional mitral regurgitation (FMR) associated with heart failure and Atrial Fibrillation mitral regurgitation Response in Mitral Loop Cerclage annuloplasty.

Inclusion Criteria:

• NYHA(New York Heart Association) Class III - IV
• and, Functional Mitral Regurgitation 3+ (Moderate/Severe) or 4+ (Severe) in spite of optimal medical treatment.

(For optimal medical treatments, ①ACE inhibitor or angiotensin receptor blocker ②β-blocker ③ aldosterone antagonists should be given for at least 3 months unless the subject has contraindication for each drug)

• and, Chronic Atrial Fibrillation in electrocardiography (Persistent AF or Permanent AF)

Exclusion Criteria:

• Primary Mitral Regurgitation
• LV ejection fraction lower than 30%
• Pulmonary arterial pressure ≥ 60mmHg
• End-diastolic Left ventricular dimension ≥ 70mm
• Subjects with functional MR who need CABG or AVR performed
• Pre-existing stent in a coronary artery that is deemed to be in direct contact with the path of mitral loop cerclage along coronary sinus
• Subjects who have functional MR caused by aortic valve disease
• Subjects who have uncontrollable hyperthyroidism
• Subjects who have severe TR due to primary valve leaflet disease
• Anomaly of Coronary Sinus
• Pre-existing devices in coronary sinus such as Implantable Cardioverter Defibrillator and Pacemaker
• 2:1 Atriventricular AV block or higher AV block and ventricular tachycardia
• Subjects with primary MR
• Subjects who cannot be screened by cardiac CT
• Subjects who have possibility of coronary artery pinching even with Mitral Loop Cerclage system judged by cardiac CT
• Subjects who do not have septal vein or have unsuitable septal vein anatomy by cardiac CT or venogram
• Subjects who have thrombosis and embolism
• Creatinine ≥2.0 mg/dL
• Subjects who have coagulation disorders
• Subjects who are unable to take anti-platelet agents
• Pre-existing devices such as Implantable Cardioverter Defibrillator and Pacemaker
• Subjects who are pregnant, or lactating, or plan pregnancy during the clinical trials
• Subjects who are participated in other clinical trials within 1 month of enrollment
• Subjects who are deemed not to be eligible in this study by physician's discretion