Rivaroxaban or Aspirin for Biological Aortic Prosthesis

Aortic valve replacement with a biological prosthesis is the most common valve surgery performed with about 1000 operations performed in Denmark each year. Further, the introduction of percutaneous stent valves will increase these types of replacements in the years to come. A biological valve is a foreign body prone to cause thrombus formation at least until the valve is covered with recipient endothelium. There are no conclusive studies of anticoagulation and the investigators have shown stroke to be a common complication. Guidelines have variably recommended aspirin or rivaroxaban for anticoagulation, and currently aspirin is the most common recommendation. In a register study, the investigators have shown that proper anticoagulation with warfarin is likely to be superior. There is a clear need for a large randomised study of aspirin versus anticoagulation for biological aortic valve replacement. This protocol describes a randomised study where 1000 patients will be randomised to receive either rivaroxaban or aspirin for 6 months following aortic valve replacement with a biological prosthesis. The primary efficacy endpoint is a combined event of all-cause mortality and hospitalisation for either acute myocardial infarction or stroke. This study has the power to settle a discussion of appropriate anticoagulation for this operation