Risk Factors of Recurrent Venous Thromboembolism: The Role of Residual Vein Thrombosis

In 313 consecutive symptomatic outpatients with proximal deep vein thrombosis (DVT) who had a conventional anticoagulation, an ultrasound assessment of the common femoral and the popliteal vein was performed three months after the acute episode, and then at 6, 12, 24, and 36 months. Veins were considered as recanalized in case of a vein diameter < 2.0 mm in a single determination, or < 3.0 mm in two consecutive determinations. Of the 58 patients who experienced recurrent episodes, 41 occurred while the patient still had residual thrombosis. The hazard ratio of recurrent thromboembolism was 2.4 (95% CI, 1.3 to 4.4; p =0.004) for persistent residual thrombosis versus early vein recanalization. In conclusion, residual venous thrombosis should be regarded as an important risk factor of recurrent thromboembolism.