Impact of Predilatation Between Self-expanding Valves

Inclusion Criteria: * Patient with severe symptomatic aortic stenosis defined by a mean aortic gradient \> 40 mmHg or peak jet velocity \> 4.0 m/s or an aortic valve area (AVA) \< 1cm2 or AVA indexed to body surface area (BSA) of \<0.6 cm2/m2 * Patient is symptomatic (heart failure with New York Heart Association (NYHA) Functional Class \> I, angina or syncope) * Patients are considered at high risk for mortality with conventional surgical aortic valve replacement as assessed by a Heart Team consisting of a cardiologist and surgeon or as confirmed by a logistic EuroSCORE I ≥ 20% and / or EuroSCORE II ≥ 7% STS score ≥ 8% OR * Over 80 years old OR * Over 65 years old with 1 or 2 (but not more than two) from the following criteria: Liver cirrhosis (Class A or B). Pulmonary insufficiency: VMS\<1 liter. Previous heart surgery (CABG, vascular surgery). Porcelain aorta. Pulmonary artery systolic pressure \>60 mmHg and high risk for heart surgery. Relapsing pulmonary embolism. Right ventricular insufficiency. Thoracic wall injuries that contraindicate an open heart surgery. History of radiation therapy of the mediastinum. Connective tissue disease that contraindicates an open heart surgery. Frailty/cachexia. * Aortic valve diameter of ≥20mm and ≤2 9mm as measured by echo. * Ascending aorta diameter ≤ 43 mm at the sinotubular junction. * Arterial aorto-iliac-femoral axis suitable for transfemoral access as assessed by conventional angiography and/or multi-detector computed tomographic angiography (access vessel diameter ≥ 6mm) * Patient understands the purpose, the potential risks as well as benefits of the trial and is willing to participate in all parts of the follow-up * Patient has given written consent to participate in the trial Exclusion Criteria: * A known hypersensitivity or contraindication to any of the following which cannot be adequately pre-medicated: aspirin or heparin and bivalirudin, ticlodipine and clopidogrel, nitinol (titanium or nickel), contrast media * Ongoing sepsis, including active endocarditis. * Any percutaneous coronary or peripheral interventional procedure with a bare metal or drug eluting stent performed within 30 days prior to Heart Team assessment. * Echocardiographic evidence of LV or LA thrombus. * Mitral or tricuspid valve insufficiency (\> grade II). * Previous aortic valve replacement (mechanical or bioprosthetic). * Recent (within 6 months of Heart Team assessment) cerebrovascular accident (CVA) or transient ischemic attack (TIA). * Patients with: Femoral, iliac or aortic vascular disease (stenosis etc) that precludes the insertion of a transcatheter sheath. OR Symptomatic carotid or vertebral artery disease (\> 70% stenosis). * The patient has a bleeding diathesis, coagulopathy or denies blood transfusion. * Estimated life expectancy of less than 12 months due to associated non-cardiac co-morbid conditions. * Creatinine clearance \< 20 ml/min. * Active gastritis or gastrointestinal ulcer. * Pregnancy. * Severe left ventricular dysfunction with left ventricular ejection fraction (LVEF) \< 20%. * Unicuspid aortic valve. * Mixed aortic valve disease (aortic stenosis and aortic regurgitation\> 2+). * Liver failure (Child-Pugh class C). * Severe dementia (resulting in either inability to provide informed consent for the study/procedure, prevents independent lifestyle outside of a chronic care facility, or will fundamentally complicate rehabilitation from the procedure or compliance with follow-up visits). * Extreme aortic valve calcification and calcific asymmetry (Agatston score: grade 4 AgS\>5000 AU). * Aortic valve area of \< 0.4 cm2.