Safety of discontinuation of anticoagulants after venous thromboembolism: whether D-dimer level should be taken into account?

Due to the continued risk of recurrence after a first episode of proximal deep vein thrombosis (DVT) of the lower extremities and/ or pulmonary embolism (PE) occurring without major transient risk factors, long-term use of anticoagulants is indicated in many cases. One attractive way to individualize the duration of treatment in these cases appears to be the assessment of blood D-dimer concentration. However, according to the prospective studies PROLONG, PROLONG II and REVERSE II, even persistent normalization of blood D-dimer concentration does not guarantee the absence of relapse. The available evidence also does not allow a differentiated approach to the assessment of the role of D-dimer for cases where proximal DVT and/or PE occurs in patients without identifiable risk factors or with minor risk factors. An attempt to clarify some of these uncertainties was made in the prospective APIDULCIS study, which included 732 patients who first had proximal DVT and/or PE, with symptoms occurring in the absence of obvious provoking factors (75.6% of cases) or associated with minor (weak) and transient risk factors (24.4%). The prerequisites included a normal blood D-dimer concentration. Patients were discontinued anticoagulants and blood D-dimer concentration measurements were repeated after 15, 30, and 60 days. If it remained low, the anticoagulant was not resumed (39.1% of cases), and when it first increased, apixaban was administered in a dose of 2.5 mg twice daily. The APIDULCIS study confirmed that anticoagulants cannot be discontinued after 1 year of use after the first unprovoked episode of proximal DVT and/or PE, even with persistent normal blood D-dimer concentration; it was shown that recurrence rate after the first episode of proximal DVT and/or PE, provoked by a minor transient risk factor, is high enough even after at least 1 year of anticoagulant treatment and at stable normal blood D-dimer concentration after their cancellation; comfirmed the effectiveness and safety of a reduced dose of apixaban (2.5 mg 2 times a day) during prolonged treatment of the first episode of proximal DVT and/or PE.