ACTION - Anticoagulation Treatment Influence on Post-operative Patients

Inclusion Criteria: Patient requires, for the first time, isolated aortic valve replacement (pacemaker insertion is allowed) Patient (or legal guardian) has signed a study specific informed consent form agreeing to the data collection and follow-up requirements. Patient is of legal age in the host country The patient is in sinus rhythm before implantation Exclusion Criteria: Patient already has a prosthetic valve, other than the valve being replaced at this time. Patient requires double valve implantation Patient requires concomitant CABG Patients requires intra aortic balloon pump at intervention Patient has a medical condition which contraindicates implantation of the SJM Epic and/or SJM Epic Supra Porcine Bioprosthetic Heart Valve (e.g. patient on dialysis) Patient requires ASA or AVK therapy, i.e. not suitable for randomization Patient is pregnant or nursing. Patient is affected by active endocarditis. Patient is affected by aortic dissection. Patient has history of cerebral ischemia Patient is affected by coagulopathy, history of GI bleeding or increased bleeding risk Patient is affected by peripheral vascular disease requiring treatment Patient has previous chronic anticoagulation therapy Patient is allergic to ASA and/or AVK