Chapter 104 Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is an acquired autoimmune disorder characterized by the presence of antiphospholipid antibodies in patients with venous and/or arterial thromboembolism or recurrent pregnancy morbidity. The association between antiphospholipid antibodies and thrombotic complications is well recognized, but the pathophysiology remains incompletely elucidated. It is thought that the binding of antiphospholipid antibodies to endothelial cells, monocytes and platelets results in a procoagulant state, which is then primed to develop thrombosis following exposure to a second hit. The diagnosis of APS is based on consensus criteria demonstrating the persistent presence of one or more antiphospholipid antibodies (lupus anticoagulant, anticardiolipin antibodies and/or anti-β2-glycoprotein I) and thrombosis that is confirmed on objective testing or histopathology, or a history of recurrent pregnancy morbidity. Anticoagulation is the mainstay of treatment in patients with APS, with ongoing controversy regarding the role of thromboprophylaxis in asymptomatic patients, the optimal antithrombotic agent in patients with ischemic stroke and the management of patients with recurrent thrombosis.