The study aims at optimizing extended management of elderly patients (> 75 years) with at least one of the known bleeding risk factor, who suffered from first episode of venous thromboembolism of the lower extremity (proximal deep vein thrombosis with or without pulmonary embolism) (VTE). Patients were randomized to receive three different treatment: Sulodexide 250 mg BIS in die; Sulodexide 500 BID in die or indistinguishable placebo to verify the efficacy and safety of extended treatment for 12 months with Sulodexide (Vessel®) in the secondary prevention of Deep Vein Thrombosis / Pulmonary Embolism (DVT/PE) recurrence.

This prospective cohort study aims to assess the efficacy and safety of the extended treatment with Sulodexide (Vessel®) in the secondary prevention of DVT / PE recurrence in elderly outpatients (≥ 75 years old at the time of inclusion) ), with at least one of the known bleeding risk factor, who had a first episode of lower extremity proximal DVT and / or PE, idiopathic or associated with weak or removed risk factors, and who have received standard treatment with any oral anticoagulant drug lasting at least 3 months. The study seeks to verify the safety of the Sulodexide therapy, demonstrating non-inferiority compared to placebo, with an incidence of major bleeding around 1% (upper confidence limit not > 3%).

Inclusion Criteria:

1. Patients with a first event of proximal lower extremity DVT and / or PE, idiopathic or associated with weak or removed risk factors.

2. Patients aged ≥75 years at the time of enrolment

3. Patients with at least one of the known risk factors of bleeding (APPENDIX 1):

   1. Hypertension
   2. Renal failure
   3. Thrombocytopenia
   4. Diabetes
   5. Antiplatelet therapy (ASA maximum 140 mg/die)
   6. Frequent falls (>2 /years)
   7. Nonsteroidal anti-inflammatory drug
   8. Liver failure
   9. Previous Stroke
   10. Anemia
   11. Poor anticoagulant control
   12. Alcohol abuse

4. Patients of both sexes.

5. Patients who at the time of enrolment have already undergone a period of anticoagulant therapy (AT, with any medication) of at least 3 months and the therapy has not been suspended for more than 30 days.

6. Patients with no other AT indications.

7. Patients capable and able to provide informed consent

Exclusion Criteria:

1. Patients aged <75 years at the time of the recruitment visit.

2. "Provoked" index event, which occurred:

   • Within 3 months of surgery or major trauma,
   • Bed Rest > 4 days,
   • Cast / immobility within 3 months.

3. Index event represented by severe PE, with life threatening risk or treated with thrombolytic therapy.

4. Index event represented by isolated distal DVT or superficial venous thrombosis.

5. Thrombotic event in sites other than the deep proximal veins of the lower limbs.

6. Anticoagulant therapy for less than 3 months at the time of enrolment.

7. Discontinuation of anticoagulant therapy for over thirty days at the time of enrolment

8. Recurrent episodes of DVT ± PE

The subjects enrolled in the study, the experimenters, and the members of the Steering Committee, Adjudication Committee, Data Monitoring and Safety Board will not be aware of the assignment of the 3 treatments following their distribution.