The optimal duration of anticoagulant therapy after unprovoked venous thromboembolism - still a challenging issue.

As about 50 % of patients with unprovoked venous thromboembolism (VTE) will develop new episodes after discontinuing therapy, indefinite treatment is suggested in patients with low or moderate bleeding risk. Baseline and post-baseline factors can help clinicians to identify patients at high risk of recurrence, who require extended treatment. Residual vein obstruction and D-dimer assay have been shown to be suitable methods for assessing the risk of VTE recurrences after a first unprovoked VTE. In treatment for VTE the use of direct oral anticoagulants (DOAC) is growing instead of the standard adjusted dose of vitamin K antagonists. The DOAC safety profile has recently been strengthened with systematic reviews and meta-analyses. Idarucizumab is only approved for the reversal of dabigatran etexilate; intravenous antidotes for factor Xa inhibitors are under development. Their advent is of great interest. In the extended treatment of VTE sulodexide has been demonstrated to significantly decrease the risk of recurrences with an excellent safety profile. Aspirin is substantially less effective than oral anticoagulants in preventing recurrences but could play a role among patients who decided to stop anticoagulants. In conclusion, for the secondary prevention of VTE several options are available, without a recognised best choice regarding the treatment duration and the choice of drugs. An individual strategy taking into account risk of recurrence, bleeding risk, therapeutic options, and patient preferences is appropriate.