Inclusion Criteria:

All candidates for this study must meet all of the following inclusion criteria:

1. Patients must have co-morbidities such that the surgeon (Co Investigator) and interventional cardiologist (Principal Investigator) concur that the predicted risk of operative mortality is > 15% with a minimum STS Risk Calculator score of ≥ 10 and/or Logistic EuroSCORE of > 20% .

   A candidate who does not meet one of the risk score minimums (STS Risk Score < 10 or a Logistic EuroSCORE < 20) can be included in the study if a peer review by at least two surgeon investigators concludes and documents that the patient's predicted risk of operative mortality is ≥ 15%. The surgeon's assessment of operative comorbidities not captured by the STS score must be documented in the study case report form as well as in the patient medical record. The following conditions with an operative mortality of ≥15% will be considered for inclusion into the trial:

   1. Porcelain aorta or other preconditions which precludes cannulation for cardiopulmonary bypass, cross-clamp application or surgical access to the mediastinum.
   2. Radiation treatment of the sternum that precludes an open chest procedure
   3. Chest deformities or remote mediastinitis that preclude an open chest procedure
   4. Other high risk conditions such as:

   i. prior thoracic or CABG surgery, ii. chronic pulmonary dysfunction - (FEV1 < 70)

2. Patient has severe senile degenerative aortic valve stenosis with a documented initial aortic valve area (AVA) of <1.0 cm2 (indexed EOA <0.6 cm2/m2), mean gradient >40 mmHg and/or jet velocity greater than 4.0 m/s. [4] (AHA 2006) (AVA baseline measurement must be within 30 days of study valve implantation procedure).
3. Patient is symptomatic from his/her aortic valve stenosis, as demonstrated by NYHA Functional Class II or greater.
4. The subject or the subject's legal representative has been informed of the nature of the study, agrees to its provisions and has provided a written informed consent that has been approved by the reviewing Ethics Committee (EC) of the respective clinical site.
5. Subject is willing to comply with specified follow up evaluations, including possible coronary angiography and transesophageal echocardiography.
6. The subject and the treating physician agree that the subject will return for all required post-procedure follow-up visits.

Exclusion Criteria:

Candidates will be excluded from the study if any of the following conditions are present:

1. Evidence of an acute myocardial infarction <1month before the intended index procedure (defined as: Q wave MI, or non-Q wave MI with total CK elevation of CK-MB > twice normal in the presence of MB elevation and/or troponin level elevation (WHO definition).
2. Aortic valve is a congenital unicuspid or bicuspid valve, or is non-calcified.
3. Mixed aortic valve disease (aortic stenosis and aortic regurgitation with predominant aortic regurgitation >3+).
4. Any therapeutic invasive cardiac procedure, other than BAV, performed within 30 days of the index procedure (or 6 months if the procedure was a drug eluting coronary stent implantation).
5. Pre-existing prosthetic heart valve in any position, prosthetic ring, or severe (greater than 3+) mitral insufficiency.
6. Presence of a pre-existing endovascular stent graft in the supra- or infrarenal aorta or pre-existing stent grafts in the ileo-femoral arteries.
7. Blood dyscrasias as defined: leukopenia (WBC<3000 mm3), acute anemia (Hb< 9 mg%), thrombocytopenia (platelet count <50,000 cells/mm³), history of bleeding diathesis or coagulopathy.
8. Untreated clinically significant coronary artery disease requiring revascularization.
9. Hemodynamic instability requiring inotropic support or mechanical heart assistance.
10. Need for emergency intervention for any reason.
11. Hypertrophic obstructive cardiomyopathy with or without obstruction (HOCM).
12. Severe ventricular dysfunction with LVEF <20%.
13. Echocardiographic evidence of intracardiac mass, thrombus or vegetation.
14. Active infection or endocarditis.
15. Active peptic ulcer or upper GI bleeding within the prior 3 months.
16. A known hypersensitivity or contraindication to aspirin, heparin, ticlopidine (Ticlid), or clopidogrel (Plavix/Iscover), or sensitivity to contrast media, which cannot be adequately pre-medicated.
17. Native aortic annulus size < 18 mm or > 21mm (23mm study valve) or < 22mm or > 25mm (26mm study valve) per the baseline echocardiogram as estimated by the left ventricular outflow tract (LVOT). Valve used (23 mm or 26 mm Edwards SAPIEN THV) to be at the discretion of the implanting physician.
18. Recent cerebrovascular accident (CVA) or neurological dysfunction (TIA) (within past 6 weeks, patients with severe senile dementia).
19. Severe renal insufficiency (creatinine >3.0 mg/dl or 265 µmol/L) and/or end stage renal disease requiring chronic dialysis.
20. Life expectancy < 12 months due to non-cardiac co-morbid conditions.
21. Significant aortic disease, including abdominal aortic or thoracic aneurysm defined as maximal luminal diameter 5 cm or greater; marked tortuosity (hyperacute bend or aortic arch >200°), aortic arch atheroma (especially if thick [> 5 mm], protruding or ulcerated) or narrowing (especially with calcification and surface irregularities) of the abdominal or thoracic aorta, severe "unfolding" and tortuosity of the thoracic aorta (applicable for transfemoral patients only).
22. Ileo-femoral vessel characteristics that would preclude safe placement of introducer sheaths such as severe obstructive calcification (including circumferential calcification), severe tortuosity (>two 90 degree bends especially where there is moderate or severe calcification), or vessels size less than 6 mm.
23. Currently participating in an investigational drug or another device study. [Note: Trials requiring extended follow-up for products that were investigational, but have since become commercially available, are not considered investigational trials].