A prospective, multicentric cohort study including 166 patients with symptomatic aortic stenosis treated with transcatheter aortic valve implantation (TAVI).

- The main objective is to determine whether the high residual platelet reactivity rates in patients undergoing TAVI is associated with the occurrence of clinical and / or subclinical prosthetic valve thrombosis measured by echocardiography and multi-slice computerized tomography

For the purpose of the study, platelet reactivity will be measured with the commercial kit PLT VASP/P2Y12 at baseline, 1day and 3 months postprocedure.

Secondary objectives include: -Determine the variability of platelet aggregation measured at baseline before the procedure, 1-day post-procedure and at 3-6 and 1 year follow-up.

• To determine whether the pro-thrombotic inflammatory response measured by the CD14 + and CD16 + quantification observed after TAVI is associated with the appearance of prosthetic thrombosis.
• To evaluate the Correlation of Von Willebrand factor levels and distribution of Von Willebrand multimers with the appearance of prosthetic thrombosis at baseline before the procedure, 1-day post-procedure and at 3, 6 months follow-up and 1 year.
• To determine whether the residual platelet reactivity rates in patients undergoing TAVI are associated with the occurrence of clinical events, at baseline before the procedure, 1-day post-procedure and at 3,6 months follow-up and 1 year
• To evaluate the clinical factors associated with the appearance of early prosthetic thrombosis.

Inclusion Criteria:

• Patients with severe symptomatic aortic stenosis who it was accepted to be treated with TAVI by a multidisciplinary team "Heat Team".
• TAVI was successfully implanted (according to Valve Academic Research Consortium II criteria) and are under treatment with double antiplatelet therapy.
• Signed informed consent to participate in this study.

Exclusion Criteria:

• Age under 18 years and pregnant or of childbearing age.
• Acute Recent stroke recent <14 days before TAVI.
• The patients with proven allergy to aspirin, clopidogrel
• Patients that after TAVI cannot undergo a double antiplatelet regimen for 6 months due to a new post-TAVI medical indication or are anticoagulated.
• Knowledge of pregnancy or lactation Thrombocytopenia (<50,000 platelets U / L) well documented and clinically relevant.
• The patients with documented moderate or severe hepatic insufficiency
• Severe chronic renal insufficiency with creatinine clearance <30 ml / min.
• The patients who can not attend the follow-up visits scheduled in the study

Patients with severe symptomatic aortic stenosis treated with TAVI