The objective of the study is to evaluate the safety and effectiveness of the HARPOON™ System in the treatment of patients with severe degenerative mitral regurgitation (DMR).

RESTORE is a prospective, multicenter, non-randomized trial designed to evaluate the safety and effectiveness of the HARPOON™ Beating Heart Mitral Valve Repair System in patients with severe degenerative mitral regurgitation (DMR).

Inclusion Criteria:

Each subject is required to meet all of the following inclusion criteria:

1. Patient is >/= 21 years old.
2. Presence of severe degenerative mitral regurgitation with mid-segment posterior leaflet prolapse (without commissural involvement) by echocardiographic study.
3. Mitral leaflet coaptation surface sufficient to reduce mitral regurgitation without undue leaflet tension, based on the judgment of the Echocardiographic Core Lab.
4. Patient competent to sign informed consent and able to return for follow-up and is capable of participating in all testing associated with this clinical investigation.

Exclusion Criteria:

Patients will be excluded if ANY of the following criteria apply:

1. Functional mitral regurgitation (FMR).

2. Evidence of anterior or bileaflet prolapse.

3. Severe mitral annular calcification (MAC).

4. Moderate or greater leaflet calcification.

5. Fragile or thinning apex (e.g. LV aneurysm).

6. Have undergone cardiac or peripheral vascular procedures within 30 days prior to the trial procedure.

7. Planned cardiac or peripheral vascular procedures within 30 days after the trial procedure.

8. Requirement for concomitant cardiac surgery.

9. Severe pulmonary hypertension (pulmonary artery systolic pressure > 60mmHg).

10. Severe aortic stenosis or insufficiency.

11. Severe tricuspid regurgitation. (Patients with mild or moderate tricuspid regurgitation are not excluded.)

12. Left ventricular ejection fraction (LVEF) <30%, or severely impaired right ventricular dysfunction as measured by the core lab.

13. Any history of endocarditis.

14. Contraindication to cardiac surgery, including hostile chest or history of mediastinal radiation.

15. Previous structural heart intervention (e.g. any heart valve replacement or repair procedures). Previous percutaneous coronary intervention (PCI) is allowed.

16. Previous coronary artery bypass grafting (CABG).

17. Stroke within 30 days prior to index procedure.

18. ST segment elevation myocardial infarction (STEMI) requiring intervention within 30 days prior to index procedure.

19. Evidence of cirrhosis or hepatic synthetic failure (Child-Pugh Class B or higher, [or MELD score of ≥ 13]).

20. Renal insufficiency CKD Stage 3b or worse (GFR < 45 ml/min/1.73 m2).

21. Hemodynamic instability or cardiogenic shock at the time of enrollment (e.g. requiring inotropic support or mechanical support devices).

22. History of bleeding diathesis or coagulopathy or leukopenia (WBC < 3000 mcL) or acute anemia (Hb < 9 g/dL) or thrombocytopenia (platelets < 50,000 cells mcL).

23. Active SARS-CoV-2 infection (Coronavirus-19 [COVID-19]) or previously diagnosed with COVID-19 with sequelae that could confound endpoint assessments (as assessed by Case Review Committee).

24. Refuse blood products.

25. Planned treatment with any other investigational device or procedure through 1-year follow-up, or who are currently participating in an investigational drug or device trial.

26. Carotid stenosis ≥ to 80% at time of enrollment.

27. Rheumatic heart disease including rheumatic mitral stenosis.

28. Pregnant or lactating at the time of enrollment (women of childbearing age should have negative pregnancy test within 72 hours of surgery) or planning pregnancy within the next 12 months.

29. Concurrent medical condition with a life expectancy of less than 12 months in the judgment of the Investigator.

30. Condition or conditions that, in the opinion of the Investigator, precludes participation, including willingness to comply with all follow-up procedures.

31. Contraindication for transesophageal echocardiography (TEE), including esophageal spasm, esophageal stricture, esophageal laceration, esophageal perforation, esophageal diverticula (e.g. Zenker's diverticulum).

32. Echocardiographic evidence of intracardiac mass (e.g. left ventricular, atrial, or appendage thrombus, myxoma, or vegetation).

33. Cannot tolerate procedural anticoagulation or post-procedure antiplatelet regimen.

    Intra-operative exclusion criteria

34. No longer meets eligibility criteria based on intra-operative assessment.

Individual participant data will not be available to other researchers.