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

Purpose: The purpose of this study was to evaluate whether low molecular we ight heparin (LMWH) could be equal or more effective than conventional oral anticoagulants (OAs) in the long-term treatment of deep venous thrombosis (DVT). Methods: One hundred fifty-eight patients with symptomatic DVT of the lower limbs confirmed by means of duplex ultrasound scan were randomized to rece ive 3 to 6 months' treatment with nadroparine calcium or acenocoumarol. Qua ntitative and qualitative duplex scan scoring systems were used to study th e evolution of thrombosis in both groups at 1, 3, 6, and 12 months. Results: During the 12-month surveillance period, two (2.5%) of the 81 pati ents who received LMWH and seven (9%) of the 77 patients who received OAs h ad recurrence of venous thrombosis (not significant). In the LMWH group no cases of major bleeding were found, and four cases (5.2%) occurred in the O A group (not significant). The mortality rate was nine (11.1%) in the LMWH group and 7.8% in the OA group (not significant). The quantitative mean dup lex scan score decreased in both groups during the follow-up and had statis tical significance after long-term LMWH treatment on iliofemoral DVT (1, 3, 6, and 12 months), femoropopliteal DVT (1-3 months), and infrapopliteal DV T (first month). Duplex scan evaluation showed that the rate of venous reca nalization significantly increased in the common femoral vein at 6 and at 1 2 months and during each point of follow-up in the superficial and poplitea l veins in the LMWH group. Reflux was significantly less frequent in commun icating veins after LMWH treatment (17.9% vs 32.2% in the OA group). The re flux rates in the superficial (22.4% in the LMWH group, 30.6% in OA group) and deep (13.4% vs 17.7%) venous system showed no significant differences b etween groups. Conclusions: The unmonitored subcutaneous administration of nadroparine in fixed daily doses was more effective than oral acenocoumarol with laborator y control adjustment in achieving recanalization of leg thrombi. With nadro parine, there was less late valvular communicating vein insufficiency, and it was at least as efficacious and safe as oral anticoagulants after long-t erm administration. These results suggest that LMWHs may therefore represen t a real therapeutic advance in the long-term management of DVT.