The small and underpowered ARTE trial (Aspirin Versus Aspirin plus Clopidogrel Following Transcatheter Aortic Valve Implantation) suggested that single- agent therapy, compared with dual-agent ther- apy, tended to reduce the risk of major adverse events (death, myocardial infarction, stroke, tran- sient ischemic attack, and major or life-threaten- ing bleeding) after TAVI. Whereas there were no CLINICAL STATEMENTS AND GUIDELINES differences between the groups with respect to death, stroke, or myocardial infarction, dual ther- apy was associated with a significantly increased risk of major or life-threatening bleeding.12 A systematic review and meta-analysis comprising approximately 2500 patients suggested that sin- gle-agent therapy is associated with fewer 30-day deaths and less major bleeding than is seen with There are several ongoing trials on this subject.39 6. The risk of thromboembolism is approximately 0.7% per year in patients with biological valves in sinus rhythm; Figure 13 is derived from several studies in which most patients were not undergo- ing therapy with VKA. Among patients with bio- prosthetic valves, those with a mitral prosthesis have higher rates of thromboembolism than do those with an aortic prosthesis (2.4% per patient- year versus 1.9% per patient-year).15 In studies of patients with bioprosthetic aortic valves who were in sinus rhythm and had no other indi- cations for anticoagulation, the incidence of thromboembolic events, bleeding, and death was similar in those who received aspirin or aspirin- like antiplatelet agents only and in those who There are no studies examin- ing the long-term effects of antiplatelet agents in patients with bioprosthetic mitral valve repair or mitral valve repair; the beneficial effects seen with bioprosthetic aortic valves may apply to mitral valves, as well.9,18 7. 