[Prevention of the extension of distal deep venous thrombosis. A randomized controlled trial with a 6-month follow-up].

Background: Deep venous thrombosis (DVT) of distal veins of the legs is important for its frequency and its potential proximal extension. The incidence of embolization in distal DVT is limited and treatment still undefined.

Methods: After diagnosing with duplex scanning a distal DVT patients were included in a 24-week follow-up. All subjects used elastic compression (stockings TED = thromboembolic deterrent) for 24 weeks after DVT. In the 4 groups the following prophylaxis for 8 weeks were used: A: oral anticoagulant (INR 2.5). B: subcutaneous calcium heparin 0.2 ml bid (8.00 and 20.00). C: subcutaneous calcium heparin (0.5 ml at 20.00). D was the control group (only elastic TED stockings). heparin 0.2 ml bid (5000 IU) and 0.5 ml once daily (12.500 IU) were used for individuals with weight range between 65 and 90 kg. No patient was admitted into hospitals. Initially 106 patients were included. There were 17 (9.6%) drop outs and after 8 weeks 177 patients completed the study. No pulmonary embolisation or side effects were observed. In one patient (control group) an important extension of the thrombus to the femoral and iliac veins was observed.

Results: The percentage of thrombus reduction was higher in the treatment groups than in controls (p < 0.05). No significant differences were found among the 3 treatment groups. At 8 weeks 88.6% of patients treated with oral anticoagulant showed improvement (stability/reduction in size of the thrombus; the percentage was 88.4% in subjects treated with subcutaneous heparin bid and 93.2% in those treated with a single dosage). In the control group thrombus increase was observed in 78.3% of patients (this difference was significant in comparison with the treatment groups; p < 0.05). At the 24-week control in 97.6% of patients in group A thrombosis was reduced/stable. This percentage was 97.7% in the ca-heparin double-dose group (B) and 100% in the single dose group (C), significantly lower than in group D (75%; p < 0.05).

Conclusions: Results indicate that untreated subjects with distal DVT are at risk of thrombus extension. In this study treatments were clinically equivalent. However one single dose of subcutaneous heparin is as effective as the double dose, is better tolerated, does not require haematological monitoring and has a lower cost.