Inclusion Criteria:  Successful trans-catheter aortic valve implantation in patients aged >65 and <80 years old at the time of the procedure.  Exclusion Criteria:  Strict indication for anticoagulation or anti-platelet drugs Strict contraindication for anticoagulation or anti-platelet drugs Overt cognitive failure Failure to obtain written informed consent Concomitant use of inducers or inhibitors of CYP3A4 or P-glycoprotein