Background/Purpose: Risk of recurrence after a first episode of venous thrombo-embolism (VTE) is strongly correlated to VTE characteristics. Indefinite anticoagulation is recommended for patients with unprovoked VTE. VTE is the most frequent manifestation of antiphospholipid syndrome (APS). However a search for antiphospholipid antibodies (aPL) is not systematically performed after a provoked thrombosis. And although long-term anticoagulation is usually advised in APS, some authors have suggested stopping anticoagulation in provoked VTE. We aimed to determine the features of venous APS, according to the provoked or unprovoked nature of the first thrombotic event.

Methods:  We performed a retrospective study of patients who met Sidney criteria of APS, revealed by VTE. Provoked event was defined as major if VTE occurred < 12 weeks after surgery, after ≥ 3 days strict immobilization, or after lower-limb fracture and as minor if VTE occurred during travel, immobilisation, sepsis, oestrogen treatment or pregnancy. Other VTE were considered unprovoked.

Results: The files of 57 women and 30 men, with a mean age of 36.2 +/- 16.1 years were reviewed. VTE presented as: deep vein thrombosis (DVT) n= 46/87, pulmonary embolism +/- DVT n= 41/87. Laboratory exams revealed: lupus anticoagulant n = 67/87, triple positivity n = 38/87. VTE was provoked by major factors in 9 and minor factors in 36/87 patients. Pregnancy and oestrogens were involved in 29 cases. Mean follow-up was 121.7 +/- 73.1 months: 27 patients presented with one or more further thrombosis; the 1st recurrence was venous in 22 and arterial in 5/27 patients; 11/27 occured under anticoagulation. We found no correlation between clinical features and 1st recurrence. We observed one death related to catastrophic APS, and six major haemorrhages. In bivariate analysis, the unprovoked nature of VTE was associated with a higher age, male sex, dyslipidemia and past history of VTE. In multivariate analysis, we found no correlation between the nature of VTE and clinical or biological features at diagnosis or during follow-up.

Conclusion:  Provoking factors are frequent in venous APS. In this venous APS cohort with numerous high risk-profile patients, provoked nature of VTE was not correlated to clinical or biological features. A search for aPL should be advised in young patients with VTE even if thrombosis is provoked. This study does not support the hypothesis of a lower risk-profile of APS patients with provoked VTE.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/venous-antiphospholipid-syndrome-is-the-unprovoked-nature-of-the-1st-thrombosis-associated-with-clinical-or-biological-features/