ALLIANCE: Safety and Effectiveness of the SAPIEN X4 Transcatheter Heart Valve

Inclusion Criteria:

   1. Severe, calcific AS

   2. Native aortic annulus size suitable for SAPIEN X4 THV

   3. NYHA functional class ≥ II

   4. 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 the
   introducer sheath or safe passage of the delivery system

   2. Aortic valve is unicuspid, bicuspid or non-calcified

   3. Pre-existing mechanical or bioprosthetic valve in any position

   4. Severe aortic regurgitation (> 3+)

   5. Severe mitral regurgitation (> 3+) or ≥ moderate mitral stenosis

   6. Need for mitral, tricuspid or pulmonic valve intervention within the next 12 months

   7. Left ventricular ejection fraction < 20%

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

   9. Left ventricular outflow tract calcification that would increase the risk of annular
   rupture or significant PVL after THV implantation

10. Increased risk of coronary artery obstruction after THV implantation

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

12. Hypertrophic cardiomyopathy with subvalvular obstruction

13. Subjects with planned concomitant ablation for atrial fibrillation

14. Complex coronary artery disease (CAD) that cannot be optimally treated by percutaneous
   coronary intervention (PCI)

15. Any surgical or transcatheter procedure within 30 days prior to the study procedure
   (unless part of planned strategy for treatment of CAD). Implantation of a permanent
   pacemaker or implantable cardioverter defibrillator (ICD) is not considered an
   exclusion.

16. Any planned surgical or transcatheter intervention to be performed within 30 days
   following the study procedure (unless part of planned strategy for treatment of CAD)

17. Endocarditis within 180 days prior to the study procedure

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

19. Hemodynamic or respiratory instability requiring inotropic or mechanical support
   within 30 days prior to the study procedure

20. Renal insufficiency and/or renal replacement therapy

21. Leukopenia, anemia, thrombocytopenia

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

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

24. Absolute contraindications or allergy to iodinated contrast that cannot be adequately
   treated with premedication

25. Subject refuses blood products

26. BMI > 50 kg/m2

27. Estimated life expectancy < 24 months

28. Female who is pregnant or lactating

29. Active SARS-CoV-2 infection or previously diagnosed with COVID-19 with sequelae that
   could confound endpoint assessments

30. Participating in another investigational drug or device study that has not reached its
   primary endpoint

31. Subject considered to be part of a vulnerable population