Comparison of Allegra vs Sapien Transcatheter Aortic Valves in Valve-In-Valve Indication

Inclusion Criteria: Patients meeting ALL the following criteria will be included: * Patients aged ≥ 18 years. * Severe haemodynamical valve deterioration of a biological aortic valve implanted surgically, including severe valve stenosis (effective aortic valve area \< 1.0 cm2) and/or severe valve regurgitation. * The patient has cardiac symptoms and/or deterioration of left ventricular ejection fraction attributable to the aortic valve disease. * Heart team decision of VIV procedure. * Patient is willing to return at 30 days for TTE and to be clinically contacted at 1 year. Exclusion Criteria: Patients meeting, at least, 1 of the following criteria will be excluded: * Patients who openly express their refusal to participate in the study. * Female patients in gestational age. * Presence or suspicious of biological aortic valve thrombosis. * Known hypersensitivity or contraindication to antithrombotic therapy (or inability to be anticoagulated during the procedure), nitinol, or sensitivity to contrast media which cannot be adequately pre-medicated. * Ongoing sepsis and/or suspicious or diagnosis of endocarditis. * Patients whose life expectancy is \< 1 year due to non-cardiac comorbid conditions. * Medical, social, or psychological conditions that preclude the subject from appropriate consent or adherence to the protocol required follow-up exams. * True inner diameter of the prosthetic valve \> 27 mm. * Transfemoral access inadequate to accommodate an 18F sheath. * Patients included in other clinical trials (excluding registries).