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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 e149 CLINICAL STATEMENTS AND GUIDELINES

of VKA anticoagulation, document time spent in the therapeutic range, exclude IE, screen for new-onset AF, and consider whether an underlying hypercoagulable state might be a contributing factor. Thromboembolism in bioprosthetic heart valve recipients should similarly raise suspicion of IE or new-onset AF in the right clinical setting. Leaflet thrombosis occurs more frequently with bioprosthetic transcatheter aortic valves than with bioprosthetic surgical aortic valves.1–4 Intensification of antithrombotic therapy should always account for individual patient bleeding risk (Figure 13).

Recommendation-Specific Supportive Text

1.	 There are no comparative-effectiveness trials from which to assess the relative utility of higher-intensity VKA therapy versus standard VKA therapy plus low-dose aspirin in mechanical valve recipients who have experienced stroke or systemic embolism while in target INR range. Excluding the common clinical occurrence of extended time in a subtherapeutic INR range is the first priority. Assessment of medication adherence, intercurrent illness, new or recently adjusted medications, dietary changes, and alcohol intake is critical. Whether to intensify VKA therapy or add lowdose aspirin is a patient-specific, shared decisionmaking proposition that must weigh several factors, including bleeding risk. 2.	 The approach to management of the patient with a systemic embolic event and a mechanical mitral prosthesis includes review of INR levels to ensure the patient is in the target INR range most of the time. INR levels may have been subtherapeutic because of suboptimal medication adherence, intercurrent illness, new or recently adjusted medications, dietary changes, or alcohol intake. Whether to intensify VKA therapy or add low-dose aspirin is a patient-specific, shared decision-making proposition that must weigh several factors, including bleeding risk. 3.	 In those patients with a bioprosthetic valve who have a stroke or embolic event, further imaging with TEE or 3D CT scanning may show leaflet thrombosis, which should respond to anticoagulation with either a VKA or a NOAC.1,2 The effectiveness of anticoagulation in aortic and mitral bioprosthetic valve recipients in whom leaflet thrombosis cannot be established as the cause of thromboembolism is uncertain, and patients should undergo a full neurological evaluation to rule out other causes of the neurological event. Shared decision-making that accounts for bleeding risk is a central feature of management. 11.6 Acute Mechanical Valve Thrombosis

11.6.1 Diagnosis of Acute Mechanical Valve Thrombosis

Recommendation for Diagnosis of Acute Mechanical Valve Thrombosis Referenced studies that support the recommendation are summarized in Online Data Supplement 38. COR LOE Recommendation

1 B-NR 1.  In patients with suspected mechanical prosthetic valve thrombosis, urgent evaluation with TTE, TEE, fluoroscopy, and/ or multidetector CT imaging is indicated to assess valve function, leaflet motion, and the presence and extent of thrombus.1–7

Synopsis

Mechanical valve thrombosis is typically a subacute to acute event resulting in rapid valve dysfunction because of abnormal or absent motion of the valve leaflets, which often is associated with inadequate VKA anticoagulation. However, recurrent valve thrombosis can be associated with pannus ingrowth in the chronic setting. Mechanical valve thrombosis can present with rapid onset of symptoms or acute pulmonary edema. Physical examination may demonstrate a stenotic murmur and muffled closing clicks, and further urgent diagnostic evaluation is required. The annual rate of prosthetic valve thrombosis with mechanical valves ranges from 0.1% to 5.7%. Higher rates of mechanical valve thrombosis are seen for some specific valve types, within the first 3 months after valve implantation and, for mechanical valves implanted in the mitral or tricuspid position compared with the aortic position.8

Recommendation-Specific Supportive Text

1.	 Mechanical prosthetic valve thrombosis is diagnosed by an abnormally elevated velocity or gradient across the prosthesis, with either limited leaflet motion or attached mobile densities consistent with thrombus, or both. Prosthetic valve obstruction is usually defined as a mean transvalvular gradient increase >50% (or an increase >10 mm Hg across an aortic prosthesis) compared with baseline, after exclusion of other causes, such as a high-output state. When mechanical valve thrombosis is suspected, imaging and Doppler data from TTE provide information on valve function, estimated pulmonary pressures, and LV size and systolic function.9 Leaflet motion should be visualized with CT or TEE (particularly for a mitral prosthesis) or fluoroscopy (for an aortic prosthesis).6,7,10–12 Prolonged periods of observation under fluoroscopy or TEE may be required to diagnose intermittent obstruction. The presence and quantification of thrombus and pannus should be evaluated by either TEE or CT.6,7,10–12

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