Antiphospholipid antibody syndrome (APS) is a common acquired
thrombophilia. The diagnosis of APS is based on both clinical and laboratory criteria. The clinical criteria include vascular
thrombosis or pregnancy morbidity. The laboratory criteria include a positive test for
lupus anticoagulant,
anticardiolipin antibodies, or anti-β(2)-glycoprotein I (anti-β(2)GPI)
antibodies on two or more occasions at least 12 weeks apart.
Antiphospholipid antibodies with
lupus anticoagulant activity may prolong
phospholipid-dependent coagulation tests such as the activated partial thromboplastin time (aPTT) and the activated clotting time (ACT). This prolongation adds a level of complexity to monitoring
heparin therapy in patients with APS who have
thrombosis. A literature search of the PubMed database was conducted for relevant articles published from 1995-April 2011. The usual management approach in nonsurgical patients with APS is to switch to
low-molecular-weight heparin. In patients in whom
heparin remains the agent of choice, management options include monitoring
heparin antifactor Xa levels, determining an individualized therapeutic aPTT range, targeting an aPTT goal of 2 times the baseline aPTT, or using an aPTT
reagent insensitive to
lupus anticoagulant. An algorithm for anticoagulation management in nonsurgical patients with APS who require
heparin is provided. The strategies to monitor intraoperative
heparin in patients undergoing cardiac surgery include measuring
heparin concentrations by an automated
protamine titration device, targeting twice the baseline ACT, using preoperative in vitro
heparin-ACT titration curves, and measuring
heparin antifactor Xa levels. The available published case reports on the use of these strategies are reviewed. Each institution should determine an approach to managing
heparin in patients with APS that best meets its needs and resources.