Low molecular weight heparin versus oral anticoagulants in the long-term treatment of deep venous thrombosis: surveillance of thrombus regression

Background: This study aims to compare the effects of low molecular weight heparin (LMWH) versus oral anticoagulants on thrombus regression and post-thrombotic syndrome (PTS) in the treatment of long-term acute deep vein thrombosis (DVT). Methods: One hundred-forty patients with acute, proximal, unilateral DVT of the lower limbs confirmed by Doppler ultrasonography were enrolled to study to receive a-six-month treatment with LMWH or vitamin K antagonist (VKA). Seventy four patients were divided into two groups except excluded patients and noncompleters. Tinzaparin sodium was administered subcutaneously once daily in a weight-adjusted dose of anti Xa 175 IU/Kg bodyweight in LMWH group, while warfarin was administered 5 mg/day for VKA group. Doppler ultrasonography was used to evaluate thrombus regression, recanalization and venous reflux at intervals of 1, 3, 6 and 12 months. All patients were followed up for 12 months. Results: Comparing ultrasonographic findings derived from both groups, the gradual reduction over time reflecting thrombus regression was more prominent in the LMWH group. A higher reduction in thrombus size in LMWH group was associated with lesser clinical events of recurrence and consequently a lesser rate of PTS. No cases of major bleeding were experienced in LMWH group, while two cases (5%) were observed in the VKA group. Conclusion: Unmonitored subcutaneous administration of LMWH at a fixed daily dose was more efficient in achieving recanalization of leg veins and safe, at least as much as oral anticoagulant, after long-term administration. These results suggest that LMWHs, compared to other treatment of choices, may represent a real therapeutic advance in the long-term management of DVT.