ALLIANCE Mitral: Safety and Effectiveness of SAPIEN X4 Transcatheter Heart Valve - Mitral

Inclusion Criteria:

1. Failing mitral surgical bioprosthetic valve or a failing native mitral valve with anannuloplasty ring demonstrating ≥ moderate stenosis and/or ≥ moderate insufficiency

2. Bioprosthetic surgical valve or native mitral annulus size suitable for SAPIEN X4THV

3. NYHA functional class ≥ II

4. Heart Team agrees the subject is at high or greater surgical risk

5. The subject has been informed of the nature of the study, agrees to its provisions,and has provided written informed consent.

Exclusion Criteria:

1. Anatomical characteristics that would preclude safe femoral placement of theintroducer sheath or safe passage of the delivery system

2. Interatrial septum or left atrium not suitable for transcatheter transseptal access

3. Failing valve has mild or greater paravalvular regurgitation

4. Failing valve is unstable, rocking, or not structurally intact

5. Annuloplasty ring dehiscence

6. Known severe patient-prosthesis mismatch or bioprosthetic valve with residual meangradient > 10 mmHg at the end of the index procedure for implantation of theoriginal valve

7. Annuloplasty ring type not favorable for THV implantation

8. Increased risk of THV embolization

9. Anatomical characteristics that would increase risk of left ventricular outflowtract (LVOT) obstruction

10. Surgical or transcatheter aortic valve extending into LVOT that may impinge on themitral implant

11. Severe right ventricle (RV) dysfunction

12. Severe regurgitation or stenosis of any other valve

13. Need for aortic, tricuspid, or pulmonic valve intervention within the next 12 months

14. Left ventricular ejection fraction < 20%

15. Cardiac imaging evidence of intracardiac mass, thrombus, or vegetation

16. Myocardial infarction within 30 days prior to the study procedure

17. Hypertrophic cardiomyopathy with subvalvular obstruction

18. Subjects with planned concomitant ablation for atrial fibrillation

19. Clinically significant coronary artery disease requiring revascularization

20. Any surgical or transcatheter procedure within 30 days prior to the study procedure.Implantation of a permanent pacemaker or implantable cardioverter defibrillator (ICD) is not considered an exclusion.

21. Any planned surgical or transcatheter intervention to be performed within 30 daysfollowing the study procedure

22. Endocarditis within 180 days prior to the study procedure

23. Stroke, transient ischemic attack or neurological signs and symptoms attributed tocarotid or vertebrobasilar disease within 90 days prior to the study procedure

24. Hemodynamic or respiratory instability requiring inotropic or mechanical supportwithin 30 days prior to the study procedure

25. Renal insufficiency and/or renal replacement therapy

26. Leukopenia, anemia, thrombocytopenia

27. Inability to tolerate or condition precluding treatment with antithrombotic therapy

28. Hypercoagulable state or other condition that increases risk of thrombosis

29. Absolute contraindications or allergy to iodinated contrast that cannot beadequately treated with premedication

30. Subject refuses blood products

31. Body mass index > 50 kg/m2

32. Estimated life expectancy < 24 months

33. Female who is pregnant or lactating

34. Active SARS-CoV-2 infection or previously diagnosed with COVID-19 with sequelae thatcould confound endpoint assessments

35. Participating in another investigational drug or device study that has not reachedits primary endpoint

36. Subject considered to be part of a vulnerable population