Treatment of the antiphospholipid syndrome with direct oral anticoagulantsPosition statement of German societies.

The antiphospholipid-syndrome (APS) is one of the most severe forms of thrombophilia, which may not only lead to recurrent venous but also to arterial thromboembolic events (TE), and to severe pregnancy complications, respectively. APS is defined by clinical symptoms and specific laboratory findings: 1. Lupus anticoagulant (LA), 2. anticardiolipin-antibodies (ACA), and 3. β2-Glycoprotein I-antibodies (β2GPI-Ab). All test results have to be confirmed after at least 12 weeks. The thrombotic risk is highest, if all 3 test groups are positive. It must be pointed out that the presence of UFH, VKA or DOACs may lead to false positive LA-test results; the addition of a specific absorber after blood sampling may provide reliable results in the presence of DOACs. A prospective randomized controlled trial comparing warfarin and rivaroxaban (TRAPS-trial) including only high-risk patients with triple positive APS was terminated early because of an increased rate of TE in patients treated with rivaroxaban [19 %, mostly arterial, compared to 3 % with warfarin (HR 7.4;1.7-32.9)]. Subsequently, a warning letter was issued by the pharmaceutical manufacturers of DOACs, including a warning of DOAC use in APS-patients, particularly in triple-positive high-risk patients. Conclusions: 1. Clinical suspicion of APS requires careful diagnostic testing. Because of inadequate diagnostic workup, many patients may not even have an APS, and these patients could be adequately treated with a DOAC. 2. Patients with single or double positive antiphospholipid antibodies but without positive LA may have a comparably low thrombotic risk and may also be treated with a DOAC in venous TE - sufficient evidence for that conclusion is not yet available but is suggested by the results of meta-analyses. 3. Triple positive patients or those with APS who suffered from arterial thromboembolism have a very high recurrence risk of thrombosis; the TRAPS-Study shows that these patients should be treated with VKA instead of a DOAC.