Venous thromboembolism in the antiphospholipid syndrome: management guidelines for secondary prophylaxis

Venous thromboembolism (VTE) in patients suffering from the antiphospholipid syndrome (APS) has been reported in almost any location of the vessel tree and the risk of recurrences has been found in several studies to be more closely associated with the presence of lupus anticoagulant than with the positivity for anti-cardiolipin antibodies. The thrombophilic state of APS raises the problem of the secondary prophylaxis to avoid VTE recurrences. For APS patients with VTE, published data appear to support a longer warfarin treatment if compared with the standard management of antiphospholipid (aPL)-negative patients with VTE. The question of how long oral anticoagulant treatment should be continued for APS patients, however, remains unanswered. Concerning the intensity of anticoagulation, several authors recommend a target international normalized ratio (INR) between 3.0 and 4.0 to efficiently protect from VTE recurrences. A recent decision analysis study does support such a suggestion. On the contrary, in a few prospective studies regimens with lower target INRs appear to be effective, and some authors therefore recommend a target INR of between 2.0 and 3.0. Specific large and prospective trials are needed to address this question. Until such information becomes available, individualized treatment according to the patient's individual risk factors for both bleeding and thrombosis is the general practice.