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February 2, 2021 Circulation. 2021;143:e72–e227. DOI: 10.1161/CIR.0000000000000923 e144

CLINICAL STATEMENTS AND GUIDELINES Otto et al 2020 ACC/AHA Guideline for the Management of Valvular Heart Disease

differences between the groups with respect to death, stroke, or myocardial infarction, dual therapy 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 single-agent therapy is associated with fewer 30-day deaths and less major bleeding than is seen with dual-agent therapy.13 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 undergoing therapy with VKA. Among patients with bioprosthetic valves, those with a mitral prosthesis have higher rates of thromboembolism than do those with an aortic prosthesis (2.4% per patientyear versus 1.9% per patient-year).15 In studies of patients with bioprosthetic aortic valves who were in sinus rhythm and had no other indications for anticoagulation, the incidence of thromboembolic events, bleeding, and death was similar in those who received aspirin or aspirinlike antiplatelet agents only and in those who received VKA.16,17,19 There are no studies examining 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.	 Many patients who undergo surgical implantation of a bioprosthetic mitral or aortic valve will not require lifelong anticoagulation in the absence of an independent indication, such as AF. However, there is an increased risk of ischemic stroke early after operation, particularly in the first 90 to 180 days after either bioprosthetic AVR or mitral valve replacement.5,24,31,34–37,40 Anticoagulation early after valve implantation is intended to decrease the risk of thromboembolism until the prosthetic valve is fully endothelialized. The potential benefit of anticoagulation therapy must be weighed against the risk of bleeding. In a nonrandomized

Figure 12. Antithrombotic therapy for prosthetic valves. Colors correspond to Table 2. *Thromboembolic risk factors include an older-generation valve, AF, previous thromboembolism, hypercoagulable state, and LV systolic dysfunction. †For a mechanical On-X AVR and no thromboembolic risk factors, a goal INR of 1.5–2.0 plus aspirin 75–100 mg daily may be reasonable starting ≥3 months after surgery. ASA indicates aspirin; AVR, aortic valve replacement; INR, international normalized ratio; MVR, mitral valve replacement; VKA, vitamin K antagonist; Rx, medication; and TAVI, transcatheter aortic valve implantation.

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