Understanding the antiphospholipid syndrome and its treatment

The antiphospholipid syndrome (APS) is a clinicopathologic disorder characterized by the persistent presence of anticardiolipin antibodies, lupus anticoagulants, or both in the plasma of patients with arterial or venous thrombosis or obstetric complications. The antiphospholipid antibodies involved in this syndrome have a relatively weak affinity for phospholipid-binding proteins such as b(2) glycoprotein I and prothrombin. In certain conditions they form bivalent antibody-protein complexes that bind with a relatively high affinity to negatively charged phospholipid surfaces. Evidence is accumulating for a pathogenetic role of antiphospholipid antibodies via interference with surface-mediated anticoagulant and procoagulant processes. The syndrome is characterized by the recurrence of thrombotic and obstetric complications. Retrospective studies have suggested that patients with APS and thrombosis need a high-intensity anticoagulant treatment. A few small prospective studies support treatment with a targeted INR of 2 to 3.