Prevention of recurrences after deep venous thrombosis: Role of low-molecular-weight heparins

The management of deep venous thrombosis (DVT) requires an initial treatment with unfractionated (UF) or low-molecular-weight (LMW) heparin followed by oral anticoagulants (OA) for at least 3 months. OA therapy, however, requires laboratory monitoring and is associated with a definite bleeding risk. Therefore, alternative treatments such as UF or LMW heparin have been evaluated. In a study by Monreal et al in patients with DVT and contraindications to OA, dalteparin (5000 anti-Xa U b.i.d.) was equivalent to UF heparin (10,000 IU b.i.d.) and was associated with fewer vertebral fractures. In a study by Pini et al, Enoxaparin (4000 anti-Xa U once daily) was evaluated against OA and showed similar efficacy with fewer bleeding complications in the 3-month treatment period. A number of studies have recently shown that the risk for late thrombotic recurrences for patients developing postoperative DVT or associated with other transient risk factors is much lower than in patients with idiopathic DVT or associated with a persistent risk factor, suggesting that for the formers, 4 to 6 weeks of OA therapy may be sufficient. LMW heparins appear to be a promising alternative therapy for these patients, because in the first month of OA administration the risk for bleeding is higher and the need of laboratory monitoring more stringent, This should be evaluated in appropriate clinical trials.