Microvascular Function in Patients Undergoing Transcatheter Aortic Valve Implant (TAVI) for Severe Symptomatic Aortic Stenosis: Association With Myocardial Fibrosis

Inclusion Criteria: • All patients referred to IRCCS Ospedale San Raffaele who are candidates to receive a TAVI implant for severe, symptomatic aortic stenosis under current appropriateness criteria and clinical practice guidelines will be considered eligible to take part in the study Exclusion Criteria: * Age \<18 years * Inability to express informed consent to take part in the present study. * Pregnancy or lactation * Pre-existing known disease determining a prognosis quo ad vitam shorter than the follow up of the present study * Significant chronic kidney disease (estimated glomerular filtration rate \<30 ml/min) * Known significant epicardial coronary artery stenosis * Known contraindication to adenosine administration: * Known allergic reactions * Second or third degree atrioventricular block before the procedure (in absence of a functional permanent pacemaker) * Long QT syndrome * Unstable angina * Severe hypotension * Acutely decompensated heart failure * Chronic obstructive pulmonary disease with bronchospasm * Concomitant use of dypiridamole