P7 Rivaroxaban may trigger catastrophic antiphospholipid syndrome

Background Catastrophic antiphospholipid syndrome (CAPS) is the most severe complication of antiphospholipid syndrome (APS). Vitamin K antagonists (VKAs) are the reference treatment for preventing relapsing thrombotic complications in patients with APS, but direct oral anticoagulants (DOACs), such as rivaroxaban, are nonetheless sometimes used in patients with antiphospholipid antibody profiles or APS. Recent studies showed that DOACs were associated with more arterial thromboses among patients with APS. The potential role of DOACs as a trigger factor of CAPS is not known. Methods We describe two patients who developed a CAPS in the week following the institution of rivaroxaban. Results We report the onset of definite CAPS in the week following introduction of rivaroxaban treatment in two patients, one with APS and the other with antiphospholipid laboratory findings only. Both were triple positive for antiphospholipid antibodies. The affected organs were the heart, kidneys, skin, and liver for Patient 1, and the heart, kidneys, skin, adrenal gland, and central nervous system for Patient 2. The causative role of rivaroxaban is highly probable given that (1) CAPS occurred rapidly after this treatment was started, (2) an alternative trigger factor was found in Patient 1 only (a colonoscopy), and (3) Patient 1 had been clinically stable for 18 years with VKA as anticoagulant treatment, while Patient 2 did not have APS and had had no symptoms for 4 months (rivaroxaban had been introduced because at a scheduled visit, she reported neurological symptoms that occurred four months before and were retrospectively compatible with a brain transient ischemic accident). One similar case was reported in 2017, also following the introduction of rivaroxaban, in a patient with triple positive venous thrombotic APS who was stable for years on warfarin and who developed definite CAPS (involvement of the myocardium and adrenal glands as well as a pulmonary embolism) in the week after rivaroxaban 20 mg daily replaced warfarin to meet the patient‘s desire for a less burdensome treatment.1 Finally, in the randomized study published by Ordi-Ros et al, one of the patients treated with rivaroxaban developed a CAPS.2 Conclusions These two cases, as well as two previous reported cases, underline the importance of avoiding DOACs in patients with APS, especially those triple positive for antiphospholipid antibodies. VKAs must remain the reference anticoagulation treatment in this setting. References Crowley MP, Cuadrado MJ, Hunt BJ. Catastrophic antiphospholipid syndrome on switching from warfarin to rivaroxaban. Thromb Res 2017; 153; 37–9. Ordi-Ros J, Saez-Comet L, Perez-Conesa M, Vidal X, Riera-Mestre A, Castro-Salomo A, et al. Rivaroxaban versus vitamine K antagonist in antiphospholipid syndrome: a randomized noninferiority trial. doi: 10.7326/M19-0291. [Epub ahead of print]; 2019