Optimal Duration of Anticoagulation in Deep Venous Thrombosis

Prospective cohort study aimed at optimizing the duration of anticoagulant treatment in patients at their first episode of proximal deep venous thrombosis (DVT) of the lower extremities, whose pathogenesis is either unknown (idiopathic DVT) or associated with minimal risk factors for thrombosis, with the help of an algorithm which incorporates both ultrasonography and D-dimer information. All patients will be followed-up until 1) the achievement of a major end-point; 2) the date of lost to to followup; 3) the date of death; 4) the date of study stop. The purpose of this study is to demonstrate the safety of withholding anticoagulation from a subgroup of patients with proximal DVT whose veins have recanalized and present with a repeatedly negative D-dimer (at baseline, after 1 and 3 months). The approach will be deemed to be safe if the annual rate of recurrent VTE in patients who will have their anticoagulation discontinued is lower than 5%.