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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 e145 CLINICAL STATEMENTS AND GUIDELINES

study, patients with a bioprosthetic mitral valve replacement who received anticoagulation had a lower rate of thromboembolism than that of those who did not receive therapy with VKA.15 Even with routine anticoagulation early after mitral valve surgery, the incidence of ischemic stroke within the first 30 postoperative days was higher after replacement with a biological prosthesis than after mitral valve repair (1.5%±0.4%) or replacement with a mechanical prosthesis.21 Small studies have not established a convincing net benefit of anticoagulation after implantation of a bioprosthetic AVR24,25; however, a large observational Danish registry demonstrated a lower risk of stroke and death with VKA, which extended up to 6 months, without a significantly increased bleeding risk.20 Concern has been raised about the incidence of subclinical bioprosthetic valve leaflet thrombosis after surgical valve replacement.19 In addition, the PARTNER 2 (Placement of Aortic Transcatheter Valves) investigators reported that the use of anticoagulation after bioprosthetic AVR in intermediate– or higher–surgical risk patients was safe and associated with a significant reduction in 6-month stroke rates.23 Ninety-five percent of the anticoagulated patients in this registry were discharged on warfarin in preference to a direct oral anticoagulant. 8.	 The prior recommendation to add low-dose aspirin to therapeutic VKA therapy for a mechanical valve prosthesis was based on studies performed decades ago that included many patients with older-generation prostheses who also had additional thromboembolic and vascular risk factors. A 2013 Cochrane Systematic Review showed that compared with anticoagulation alone, the addition of an antiplatelet agent reduced the risk of thromboembolic events and the total mortality rate but at the cost of an increased and offsetting risk of major bleeding.26 The authors pointed out that the quality of the included trials tended to be low, possibly reflecting the era when most trials were conducted. An individualized approach that takes the risk of bleeding into account is required. 9.	 In patients without risk factors who receive a mechanical On-X aortic heart valve (On-X Life Technologies Inc., Austin, Texas), targeting the INR to a lower goal (1.5–2.0) in conjunction with aspirin 81 mg daily may be a strategy for long-term management. Warfarin dosing is targeted to an INR of 2.5 (range, 2.0–3.0) for the first 3 months after surgery, during which lowdose aspirin is also used.27 This recommendation is based on a single RCT27 of lower- versus standard-intensity VKA therapy (with low-dose aspirin) in patients undergoing On-X AVR. The lower-intensity INR group experienced significantly less major and minor bleeding, whereas the rates of stroke, transient ischemic attack, total neurological events, and all-cause mortality were similar between the 2 groups. A subsequent publication from these investigators showed harm with a strategy of dual-antiplatelet therapy versus low-intensity anticoagulation plus low-dose aspirin.28

10.  The routine use of dual-antiplatelet therapy for 6 months after TAVI, which has been the default strategy since the introduction of this technology into clinical use, has been not been rigorously assessed (see previous discussion). There are several ongoing trials evaluating antithrombotic strategies after TAVI. A small, single-center RCT of patients receiving a self-expanding TAVI device showed no difference in a composite endpoint of major adverse cardiac and cerebrovascular events or life-threatening bleeding with aspirin plus clopidogrel versus aspirin alone at 30 days and 6 months.29 Compared with singleagent therapy, dual-antiplatelet therapy may be associated with a higher risk of bleeding and no significant difference in rates of valve leaflet thrombosis, thromboembolism, or valve performance.12,13 Other procedural and patient factors may impact the decision to use dual-antiplatelet therapy. 11.  The selective use of VKA therapy might be considered after TAVI in patients at low bleeding risk on an individual basis. The PARTNER 2 investigators reported that the use of an anticoagulant (95% warfarin) after TAVI in intermediate– or higher– surgical risk patients was associated with a lower incidence of an increase in mean gradient >10 mm Hg over the first year after implantation.23 This Doppler finding may reflect the development of leaflet thrombosis, for which a change in the frequency of follow-up examinations or treatment could be considered. VKAs may be more effective than direct oral anticoagulants for reduction of death, myocardial infarction, and cerebrovascular events in patients undergoing TAVI with an indication for anticoagulation.33 The selective shortterm use of VKAs after ViV TAVI is predicated on the observation that valve thrombosis may be more frequent in this patient population.32 12.  The GALILEO (Global Study Comparing a Rivaroxaban-based Antithrombotic Strategy to an Antiplatelet-based Strategy after Transcatheter Aortic Valve Replacement to Optimize Clinical Outcomes) trial assessed a strategy of low-dose rivaroxaban (10 mg daily) plus low-dose aspirin (75–100 mg daily) versus an antiplatelet strategy

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