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Otto et al 2020 ACC/AHA Guideline for the Management of Valvular Heart Disease

Circulation. 2021;143:e72–e227. DOI: 10.1161/CIR.0000000000000923 February 2, 2021 e143 CLINICAL STATEMENTS AND GUIDELINES

for patients with mechanical valve prostheses. Oral antithrombin and anti-Xa agents are not approved for use in these patients. The addition of mono- or dual-antiplatelet therapy to VKA treatment for other indications (eg, acute coronary syndrome or percutaneous coronary intervention [PCI]) must be done with caution. The evidence base for the optimal antithrombotic strategy across subgroups of patients who have received a bioprosthetic valve is not robust. Practice patterns around the use of antiplatelet and anticoagulant medications in these patients vary as a function of method of implantation (surgical versus transcatheter), the presence of any independent indication for anticoagulation (eg, AF, venous thromboembolic disease), and local/institutional care pathways (Figure 12).

Recommendation-Specific Supportive Text

1.	 All patients with mechanical valves require lifelong anticoagulant therapy with a VKA.1–5 In addition to the thrombogenicity of the intravascular prosthetic material, mechanical valves impose abnormal flow conditions, with zones of low flow within their components, as well as areas of high-shear stress, which can cause platelet activation that leads to valve thrombosis and embolic events. Therapy with an oral VKA at an INR goal appropriate for the comorbidity of the patient and the type and position of the mechanical valve prosthesis is required to decrease the incidence of thromboembolism and associated morbidity. Data show that anticoagulation with a VKA is protective against valve thrombosis (OR: 0.11; 95% CI: 0.07–0.2) and thromboembolic events (OR: 0.21; 95% CI: 0.16–0.27). It is preferable to specify a single INR target for each patient and to recognize that the acceptable range includes 0.5 INR units on each side of this target. A specific target is preferable because it reduces the likelihood of patients having INR values consistently near the upper or lower boundary of the range. Fluctuations in INR are associated with an increased incidence of complications in patients with prosthetic heart valves.19,38 2.	 The rate of thromboembolism in patients with a bileaflet mechanical AVR treated with a VKA is estimated to be 0.53% per patient-year over the INR range of 2.0 to 4.5. In a large retrospective study, adverse events increased if the INR was >4.0 in patients with a mechanical AVR. In patients with a current-generation mechanical AVR without other risk factors for thromboembolism, in the group treated to an INR of 2.0 to 3.0, the risk of thromboembolic events was similar to, but the risk of bleeding lower than, those of the group treated to an INR of 3.0 to 4.5 (P<0.01).7 In a randomized trial comparing moderate-intensity (INR 2.0–3.0) with high-intensity (INR 3.0 to 4.5) oral anticoagulation in patients with a single mechanical valve replacement, there was no difference in embolic events but a reduction in bleeding with the moderate-intensity group.8 In a study comparing an INR target of 1.5 to 2.5 with a target of 2.0 to 3.0 in patients with current-generation mechanical aortic prosthetic valves and no other thromboembolic risk factors, the lower INR target range was noninferior, but the quality of the evidence was low.6 For current-generation mechanical valve prostheses in the aortic position, an INR of 2.5 (range, 2.0–3.0) provides a reasonable balance between the risks of thromboembolism and bleeding.8,9

3.	 In patients with an aortic mechanical prosthesis who are at higher risk of thromboembolic complications, the INR should be maintained at 3.0 (range, 2.5–3.5). Risk factors include AF, previous thromboembolism, hypercoagulable state, and older-generation prosthesis (eg, ball-in-cage).10 Severe LV dysfunction may also increase thromboembolic risk.9 4.	 The incidence of thromboembolism is higher with mitral than with aortic mechanical valves, and it is lower in mitral mechanical valve patients with a higher rather than a lower INR. In the GELIA (German Experience with Low Intensity Anticoagulation) study of patients with a mechanical mitral prosthesis, a lower INR range (2.0–3.5) was associated with a lower survival rate than that seen with a higher target INR range (2.5–4.5).11 Patient compliance may be challenging with higher INR goals. In one study, patients with a target INR between 2.0 and 3.5 were within that range 74.5% of the time. In contrast, patients with a target INR of 3.0 to 4.5 were within range only 44.5% of the time. An INR target of 3.0 (range, 2.5–3.5) provides a reasonable balance between the risks of under- or over-anticoagulation in patients with a mechanical mitral valve.9 5.	 Prior recommendations about the use of antiplatelet therapy after TAVI were derived from the protocols used in the pivotal randomized studies showing the safety and effectiveness of this technology. These protocols were in turn adopted from studies of patients undergoing PCI. The small and underpowered ARTE trial (Aspirin Versus Aspirin plus Clopidogrel Following Transcatheter Aortic Valve Implantation) suggested that singleagent therapy, compared with dual-agent therapy, tended to reduce the risk of major adverse events (death, myocardial infarction, stroke, transient ischemic attack, and major or life-threatening bleeding) after TAVI. Whereas there were no

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