Six Years of Follow-up After Extended Duration of Oral Anticoagulant Therapy for a First Episode of Idiopathic Pulmonary Embolism or Proximal Deep Vein Thrombosis.

Beyond the first 6 months of anticoagulation, patients with a first episode of unprovoked venous thromboembolism have a high risk of recurrence after stopping anticoagulations (about 10% at one year and 30% at 5 years). Extending anticoagulant therapy for an additional 18 months is associated with a major reduction of recurrent VTE; however this benefit tended to be lost after stopping anticoagulation during a follow-up period of two years. This has been well demonstrated in the double-blind randomized PADIS PE trial comparing 2 years with 6 months of anticoagulation and a follow-up of two years after study treatment discontinuation. This risk of recurrence is likely to continuously increase over the years as well as the risk of chronic thromboembolic pulmonary hypertension (after pulmonary embolism) or the risk of post-thrombotic syndrome (after deep vein thrombosis). In addition, risk factors of such complications remain uncertain. The first aim of the PADIS-EXTENSION trial is to estimate these risks over 6 years of follow-up in patients who have been initially treated during 6 months or 24 months (patients included in the PADIS PE and PADIS DVT trial). Secondary aims are to identify risk factors of these complications during long-term follow-up.