[Treatment of deep venous thrombosis by low molecular weight heparins. Comments on the recommendations of the North American Consensus].

LMW heparins have recently come into use in North America for treatment of venous thrombosis. Their first line recommendation is a major innovation of the last north american consensus conference on antithrombotics published in Chest at the beginning of 2001. This recommendation is grade 1A regarding its advantageous benefit-risk ratio. An earlier oral vitamine K antagonist treatment and a more regular nomogram use allow to reduce the relay duration and to obtain more often the targeted INR. The more predictable anticoagulant response with weight-based doses induces a simplified anti-Xa activity survey limited to renal dysfunction and obese or less than 50 Kg body weight persons but a regular platelet count remains mandatory. Several questions need to be discussed: once or twice daily subcutaneous injection use and treatment duration which seem related to the persistence of triggering factors, the variety of thrombophilia and comorbidity conditions. Due to a greater evidence-based medicine, the antithrombotic strategy becomes more related to a closer evaluation of the individual thrombotic risk level.