ACURATE IDE: Safety and Effectiveness Study of ACURATE Valve for Transcatheter Aortic Valve Replacement

Inclusion Criteria:

   - IC1. Subject has documented severe symptomatic native aortic stenosis defined as
   follows: aortic valve area (AVA) ≤1.0 cm2 (or AVA index ≤0.6 cm2/m2) AND a mean
   pressure gradient ≥40 mmHg, OR maximal aortic valve velocity ≥4.0 m/s, OR Doppler
   velocity index ≤0.25 as measured by echocardiography and/or invasive hemodynamics.

Note: In cases of low flow, low gradient aortic stenosis with left ventricular dysfunction
(ejection fraction <50%), dobutamine can be used to assess the grade of aortic stenosis
(maximum dobutamine dose of 20 mcg/kg/min recommended); the subject may be enrolled if
echocardiographic criteria are met with this augmentation.

   - IC2. Subject has a documented aortic annulus size of ≥20.5 mm and ≤29 mm based on the
   center's assessment of pre-procedure diagnostic imaging (and confirmed by the Case
   Review Committee [CRC]) and, for the Main Randomized Cohort and the Extended
   Durability Study, is deemed treatable with an available size of both test and control
   device.

   - IC3. For subjects with symptomatic aortic valve stenosis per IC1 definition above,
   functional status is NYHA Functional Class ≥ II.

   - IC4. Heart team (which must include an experienced cardiac interventionalist and an
   experienced cardiac surgeon) agrees that the subject is indicated for TAVR, is likely
   to benefit from valve replacement, and TAVR is appropriate.

   - IC5. Subject (or legal representative) understands the study requirements and the
   treatment procedures, and provides written informed consent.

   - IC6. Subject, family member, and/or legal representative agree(s) and subject is
   capable of returning to the study hospital for all required scheduled follow up
   visits.

   - IC7. Subject is expected to be able to take the protocol-required adjunctive
   pharmacologic therapy.

Exclusion Criteria:

   - EC1. Subject has a unicuspid or bicuspid aortic valve.

   - EC2. Subject has had an acute myocardial infarction within 30 days prior to the index
   procedure (defined as Q-wave MI or non-Q-wave MI with total CK elevation ≥ twice
   normal in the presence of CK-MB elevation and/or troponin elevation).

   - EC3. Subject has had a cerebrovascular accident or transient ischemic attack
   clinically confirmed by a neurologist or neuroimaging within the past 6 months prior
   to study enrollment.

   - EC4. Subject is on renal replacement therapy or has eGFR <20.

   - EC5. Subject has a pre-existing prosthetic aortic or mitral valve.

   - EC6. Subject has severe (4+) aortic, tricuspid, or mitral regurgitation.

   - EC7. Subject has moderate or severe mitral stenosis (mitral valve area ≤1.5 cm2 and
   diastolic pressure half-time ≥150 ms, Stage C or D76).

   - EC8. Subject has a need for emergency surgery for any reason.

   - EC9. Subject has a history of endocarditis within 6 months of index procedure or
   evidence of an active systemic infection or sepsis.

   - EC10. Subject has echocardiographic evidence of new intra-cardiac vegetation or
   intraventricular or paravalvular thrombus requiring intervention.

   - EC11. Subject has platelet count <50,000 cells/mm3 or >700,000 cells/mm3, or white
   blood cell count <1,000 cells/mm3.

   - EC12. Subject has had a gastrointestinal bleed requiring hospitalization or
   transfusion within the past 3 months, or has other clinically significant bleeding
   diathesis or coagulopathy that would preclude treatment with required antiplatelet
   regimen, or will refuse transfusions.

   - EC13. Subject has known hypersensitivity to contrast agents that cannot be adequately
   pre-medicated, or has known hypersensitivity to the protocol required medications
   (aspirin, all P2Y12 inhibitors, heparin), or to the individual components of the test
   or control valve (nickel, titanium, stainless steel, platinum, iridium or polyethylene
   terephthalate [PET]).

   - EC14. Subject has a life expectancy of less than 12 months due to non-cardiac,
   comorbid conditions based on the assessment of the investigator at the time of
   enrollment.

   - EC15. Subject has hypertrophic cardiomyopathy.

   - EC16. Subject has any therapeutic invasive cardiac or vascular procedure within 30
   days prior to the index procedure (except for balloon aortic valvuloplasty, pacemaker
   implantation, or implantable cardioverter defibrillator implantation, which are
   allowed).

   - EC17. Subject has untreated coronary artery disease, which in the opinion of the
   treating physician is clinically significant and requires revascularization.

   - EC18. Subject has severe left ventricular dysfunction with ejection fraction <20%.

   - EC19. Subject is in cardiogenic shock or has hemodynamic instability requiring
   inotropic support or mechanical support devices.

   - EC20. Subject has arterial access that is not acceptable for the study device (test or
   control) delivery systems as defined in the device (test or control) Directions For
   Use.

   - EC21. Subject has either of the following:

      - Severe vascular disease that would preclude safe access (e.g., aneurysm with
      thrombus that cannot be crossed safely; marked tortuosity; significant narrowing
      of the abdominal aorta; severe unfolding of the thoracic aorta; or thick,
      protruding, ulcerated atheroma in the aortic arch), OR

      - Severe/eccentric calcification of the aortic annulus that would prevent safe
      implantation of the TAVR prosthesis.

   - EC22. Subject has current problems with substance abuse (e.g., alcohol, etc.) that may
   interfere with the subject's participation in this study.

   - EC23. Subject is participating in another investigational drug or device study that
   has not reached its primary endpoint or subject intends to participate in another
   investigational device clinical trial within 12 months after index procedure.

   - EC24. Subject has untreated conduction system disorder (e.g., Type II second degree
   atrioventricular block) that in the opinion of the treating physician is clinically
   significant and requires a pacemaker implantation. Enrollment is permissible after
   permanent pacemaker implantation.

   - EC25. Subject has severe incapacitating dementia.

Additional exclusion criteria apply to subjects considered for enrollment in the CT Imaging
Substudy as listed below.

   - AEC1. Subject has eGFR <30 mL/min (chronic kidney disease stage IV or stage V)

   - AEC2. Subject has atrial fibrillation that cannot be rate controlled to ventricular
   response rate < 60 bpm.

   - AEC3. Subject is expected to undergo chronic anticoagulation therapy after the index
   procedure.

Note: Subjects treated with short-term anticoagulation post procedure can be included in
the CT Imaging Substudy; in these subjects the 30-day imaging will be performed 30 days
after discontinuation of anticoagulation.