Pitfalls of Commonly Used Anticoagulation Monitoring Techniques in Antiphospholipid Syndrome During Cardiopulmonary Bypass

Antiphospholipid Syndrome (APS) is an immunologic disorder that causes a state of hypercoagulability that can result in recurrent venous and arterial thromboses. Patients who experience APS may develop cardiac manifestations requiring surgical intervention, such as valvular thickening or chronic thromboembolic pulmonary hypertension. APS is seen in up to 10% to 20% of patients with chronic thromboembolic pulmonary hypertension presenting for pulmonary thromboendarterectomy (PTE). Patients with APS are at particularly high risk during cardiac surgery, with early mortality of up to 20% and morbidity of nearly 50%. Perioperative management of antithrombotic therapy in patients with APS is complicated by the fact that in vitro tests of coagulation, such as the activated partial thromboplastin time and the activated clotting time (ACT), are falsely elevated at baseline as a result of antibody inhibition of phospholipid-dependent coagulation during in vitro testing. The importance of careful management of hemostasis in these patients is demonstrated in the major complications that have been shown to occur, related both to states of hypercoagulability and coagulopathy. Several strategies for the management of anticoagulation in these patients have been proposed, but there is no clear consensus. Herein the authors report a case of a patient with APS undergoing PTE that highlights several limitations of the available coagulation monitoring strategies. The patient provided written consent for publication of the details of the case.