Colibri Transcatheter Aortic Heart Valve System Study

Inclusion Criteria: * 1\. Subject of age \> 75 years * 2\. Subject suffering from severe aortic tricuspid valve stenosis defined as follows: High-gradient aortic stenosis (mean pressure gradient across aortic valve \> 40 mmHg or peak velocity \> 4.0 m/s) * 3\. Subject has symptomatic aortic valve stenosis with New York Heart Association (NYHA) \> Class II * 4\. Subject with a documented local Heart Team (HT) agreement of high surgical risk as described in the population * 5\. ECG-gated Multi-Slice Computed Tomographic (MSCT) measurements determined an aortic annulus \> 22 mm and \< 27.4 mm * 6\. Subject deemed eligible by a TAVI Centralized Case Review Committee (CRC) * 7\. Subject can understand the purpose of the clinical investigation, has signed voluntarily the informed consent form and is agreeing to the scheduled follow-up requirements Exclusion Criteria: * 1\. Arterial aorto-iliac-femoral axis unsuitable for transfemoral access as assessed by conventional angiography and/or multidetector computed tomographic angiography (access vessel diameter incompatible with a 16F sheath introducer) * 2\. Aortic root anatomy condition or lesion preventing implantation or access to the aortic valve * 3\. Non-calcific acquired aortic stenosis * 4\. Native unicuspid/bicuspid aortic valve or congenital aortic valve abnormality * 5\. Previous implantation of heart valve in any position * 6\. Severe aortic regurgitation (\> 3+) * 7\. Severe mitral regurgitation (\> 3+) * 8\. Severe tricuspid regurgitation (\> 3+) * 9\. Severe left ventricular dysfunction (Left Ventricular Ejection Fraction (LVEF) \< 30%) * 10\. Echocardiographic evidence of intracardiac mass, thrombus or vegetation * 11\. Multi-vessel coronary artery disease (CAD) with a Syntax Score or residual Syntax Score \> 22 and/or unprotected left main coronary artery * 12\. Cardiogenic shock * 13\. Untreated cardiac conduction disease in need of pacemaker implantation * 14\. Uncontrolled atrial fibrillation (resting heart rate (HR) \> 120bpm) * 15\. Active and/or suspicion of endocarditis or ongoing sepsis * 16\. Blood dyscrasias defined as: leukopenia (White Blood Cells (WBC) \< 1,000/mm3), thrombocytopenia (Platelets (PLT) \< 50,000/mm3), history of bleeding diathesis or coagulopathy, or hypercoagulable states * 17\. Evidence of acute myocardial infarction (MI) less than 30 days before signing informed consent * 18\. Any need for emergency surgery * 19\. Recent (\< 6 months of signing informed consent) CerebroVascular Accident (CVA) or Transient Ischemic Attack (TIA) * 20\. Symptomatic carotid or vertebral artery disease or successful treatment of carotid stenosis \< 30 days prior to signing informed consent * 21\. Any active bleeding that precludes anticoagulation * 22\. Liver failure (Child-C) * 23\. End-stage renal disease requiring chronic dialysis or creatinine clearance \< 20cc/min * 24\. Pulmonary hypertension (systolic pressure \>80mmHg) * 25\. Severe Chronic Obstructive Pulmonary Disease (COPD) demonstrated by a Forced Expiratory Volume (FEV1) \< 750cc * 26\. Refusal of blood transfusion * 27\. A known hypersensitivity or contraindication to all anticoagulation/anti-platelet regimens (or inability to be anticoagulated for the index procedure), to cobalt chromium, to porcine and/or collagen, to glutaraldehyde or contrast media * 28\. Any medical, social or psychological condition that in the opinion of the investigator precludes the subject from giving appropriate consent or adherence to the required follow-up procedures * 29\. Currently participating in another drug or device trial (excluding observational registries) for which the primary endpoint has not been assessed * 30\. Estimated life expectancy of less than 12 months * 31\. For females, pregnancy or intention to become pregnant prior to completion of all follow-up procedures * 32\. Inability to comply with the clinical investigation requirements * 33\. Subject under judicial protection, tutorship or curatorship (for France only)