NPPB and aortic stenosis: -Reference procedure for the treatment of AS-Patient aged < 65 years or with life expectancy > 20 years-Patients with severe asymptomatic AS and an abnormal exercise test, very severe AS, rapid progression of AS, or a high BNP level-Stenotic valve is replaced with a bioprosthetic or mechanical valve-Patients in whom anticoagulation is contraindicated should not be candidates for mechanical AVR-Mechanical AVR is recommended for patients aged < 50 years with no contraindication to anticoagulation-Bioprosthesis AVR is recommended for patients > 65 years