Reduction or Elimination of Mitral Regurgitation With the SATURN TMVR System (CASSINI-US)

Inclusion Criteria: * Age 18 years or older. * Symptomatic, moderate to severe or severe, functional or mixed, mitral regurgitation (≥ Grade 3+). * NYHA functional Class ≥ II. If Class IV, patient must be ambulatory. * Ability to tolerate oral anticoagulation. * Ability to qualify for bailout surgery (which may include open heart surgery). * High risk for open-heart mitral valve surgery due to age, co-morbidities or frailty, as determined by the Heart Team. * Willing and able to complete study-related assessments and questionnaires. Exclusion Criteria: * Purely degenerative (organic/primary) (i.e. intrinsic valve lesions) mitral regurgitation. * Excessive frailty or comorbid conditions that preclude the anticipated benefit of the mitral valve replacement. * Life expectancy \<1 yr. due to noncardiac conditions. * Endocarditis in the 3 months prior to procedure date. * Current admission with acute heart failure exacerbation. * Dependency on inotropic agents or mechanical circulatory support. * Untreated clinically significant CAD. * Active systemic infection. * Modified Rankin Scale ≥4 disability. * Chronic renal failure defined as eGFR \< 30 mL/min/m2 or on renal replacement therapy. * Severe pulmonary arterial hypertension (PAH), defined as PASP \> 70mmHg. * Platelets \< 90,000. * COPD on home oxygen therapy deemed too high risk for intubation. * Refuses blood transfusions. * Documented bleeding or coagulation disorders (hypo- or hyper-coagulable states). * Severe connective tissue disease under chronic immunosuppressive or cortisone therapy. * Participating in other investigational studies likely to confound the results or affect the study. * Unable or does not sign the study informed consent form. * Patients classified as "vulnerable patients" Cardiovascular Exclusion Criteria * Myocardial infarction during prior 30 days. * Stroke or TIA during prior 90 days. * Severe extracardiac arteriopathy (safety measure for extra-circulatory support if surgical conversion is needed). * Prior mitral valve treatment (e.g., valve repair or replacement, MitraClip, etc.), and/or anticipated mitral valve treatment prior to enrollment. * Prior surgical mechanical valve AVR. * Prior TAVI. -Need for any planned cardiovascular surgery or intervention (other than for MV disease) within 30 days post-index procedure. * CRT, CRT-D, IPG or ICD implanted in previous 30 days. * Cardiogenic shock, hemodynamic instability, Systolic Blood Pressure \<90mmHg, Inotropic dependent or IABP/mechanical circulatory support. CABG or PCI within previous 30 days. * Inadequately treated for cardiac condition per applicable standards, such as for coronary artery disease, left ventricular dysfunction, mitral regurgitation, or heart failure, as reviewed by the Patient Screening Committee. * Prior or planned heart transplantation (UNOS status 1). * Physical evidence of right-sided CHF: 1. Patients with ascites. 2. Patients with anasarca (generalized edema / hydropsy). * Hypertrophic cardiomyopathy, restrictive cardiomyopathy, constrictive pericarditis, or other structural heart disease causing heart failure with the exception of dilated ischemic or non-ischemic cardiomyopathy. Procedural Exclusion Criteria * Known hypersensitivity or contraindication to procedural or post-procedural medication (e.g., contrast solution, anticoagulation therapy). * Documented hypersensitivity to nickel or titanium. Cardiac Imaging Exclusion Criteria (evaluated by Core Labs) * Contraindications to TEE imaging * Left ventricular EF ≤ 30% by echocardiogram. * Severe mitral annular calcification, severe mitral stenosis, valvular vegetation or mass. * Extensive mitral flail leaflets * Evidence of new or untreated intracardiac thrombus, mass, or vegetation. * Severe right ventricular dysfunction. * Severe tricuspid regurgitation. * Hemodynamically significant inter-atrial shunt (ASD). * Severe aortic regurgitation or aortic stenosis. * Anatomic ineligibility for SATURN Valve or SATURN TS procedure as determined by the Screening Committee.