The purpose of this study is to determine that Transcatheter aortic valve replacement (TAVR) with SAPIEN 3 is superior to traditional surgical aortic valve replacement(SAVR) with bio-prosthesis regarding the rate of all-cause mortality at 1 year in patients with symptomatic severe aortic valve stenosis.

Inclusion Criteria:

• Age must be at least 19 and less than 75 years old
• Severe aortic valve stenosis with echocardiographically derived criteria: mean gradient > 40mmHg or jet velocity greater than 4.0 m/s AND an initial aortic valve area (AVA) of ≤ 0.8 cm2. Echocardiogram must be within 3 months of the date of the procedure
• Patient is symptomatic from his/her aortic valve stenosis, as demonstrated by NYHA class II or greater.
• The patient or guardian agrees to the study protocol and the schedule of clinical and angiographic follow-up, and provides informed, written consent, as approved by the appropriate Institutional Review Board/Ethical Committee of the respective clinical site.

Exclusion Criteria:

• Life expectancy <1 year due to medical illness
• Suspected Malignancy
• Inoperability evaluated by surgeon
• Concomitant severe coronary artery disease not amenable for percutaneous coronary intervention
• Concomitant severe mitral valve or significant aorta disease requiring surgery
• Active bacterial endocarditis within 6 months of procedure
• Leukopenia (WBC<3000 cell/mL), acute anemia (Hgb<8g/dL), thrombocytopenia (platelet < 50000 cell/mL)
• Intracardiac thrombus
• A known contraindication or hypersensitivity to all anticoagulation regimens, or inability to be anticoagulated for the study procedure.
• Native aortic annulus size < 18 mm or > 25 mm as measured by echocardiogram.
• Expectation that patient will not improve despite treatment of aortic stenosis
• Patients who are actively participating in another drug or device investigational study, which have not completed the primary endpoint follow-up period.