Management of Thrombotic Microangiopathy and Mechanical Valve Thrombosis

Diagnosis and Treatment

The American College of Cardiology recommends obtaining multimodality imaging immediately to assess valve function, leaflet motion, and thrombus burden in cases of suspected mechanical valve thrombosis 1, 8
The American Heart Association suggests that patients with mechanical heart valves and suspected thrombotic microangiopathy (TMA) should maintain therapeutic anticoagulation with warfarin throughout TMA treatment, with an INR target of 2.5 for mechanical aortic valve replacement (AVR) and 3.0 for mechanical mitral valve replacement (MVR) 3, 4
The American College of Cardiology advises against interrupting warfarin therapy during TMA treatment, as the mechanical valve thrombosis risk outweighs bleeding concerns from plasma exchange 4, 3
The American College of Cardiology recommends against using direct oral anticoagulants (DOACs) in mechanical valve patients, even during acute illness 6

For symptomatic left-sided mechanical valve obstruction, the American College of Cardiology suggests choosing between slow-infusion fibrinolytic therapy or emergency surgery based on factors such as readily available surgical expertise, NYHA class symptoms, clot burden, and presence of left atrial thrombus 1, 2, 9
The American College of Cardiology recommends using a low-dose, slow-infusion protocol of tissue plasminogen activator (tPA) 25 mg over 25 hours, with repeat dosing if needed, for fibrinolytic therapy in mechanical valve thrombosis 1, 9

The American Heart Association suggests adjusting warfarin doses to maintain therapeutic INR despite plasma infusion in patients with mechanical heart valves and TMA 3
The American College of Cardiology advises against using heparin bridging during active TMA, and instead recommends maintaining oral warfarin with INR monitoring 3