Inclusion Criteria1. Adult patients (more than 18 years) with ability to understand and accept the participation in the clinical trial.
2. Patients with symptomatic degenerative severe aortic stenosis rejected for conventional surgical aortic valve replacement due to unacceptably high risk and accepted for TAVI procedure
3. Signed informed consent.
4. Patients who are not participating in any other clinical trial or research study.
Exclusion Criteria1. Patients under oral anticoagulation treatment
2. Patients who can not undergo MRI study
3. Recent stroke < 14 days prior, revascularized coronary artery disease or life expectancy < 12 months
4. Patients with proven allergy to aspirin, clopidogrel or acenocoumarol
5. Patients that after TAVI procedure can not undergo a regimen of dual antiplatelet therapy or oral anticoagulation for 3 months due to any new post-TAVI medical indication