Introduction: The incidence of venous thromboembolism (VTE) in children appears to be increasing, and warfarin remains one of the few standard anticoagulants used for secondary VTE prevention. When invasive procedures are required in adults with high TE risk who are receiving warfarin, low-molecular weight heparin (LMWH) bridging is recommended, based mainly upon observational evidence; in children, no such studies have been published. We sought to determine the risks of recurrent TE (both VTE and arterial TE [ATE]) and major bleeding with peri-procedural LMWH bridging in children receiving warfarin for VTE. Methods: Children (age ≤ 21 years of age at the time of bridge) receiving warfarin for VTE and undergoing a standardized clinical care protocol for peri-procedural LMWH bridging were enrolled and followed in an institution-based prospective inception cohort study at Children's Hospital Colorado between March 2006 and February 2012. Outcomes were assessed at 30 days post-procedure, and followed International Society on Thrombosis and Haemostasis guidelines. Results: Seventeen children comprised the cohort, with a total of 23 bridging episodes. Median age at bridging episode was 17.5 years (range, 12 to 21 years). In 22% of bridging episodes, indication was for major surgery. Median duration of LMWH administration prior to procedure was 6 days (range, 4-10 days); median duration off anticoagulation peri-procedurally was 1.5 days (range: 1-2 days). The risks of major bleeding, recurrent VTE, and ATE at 30 days post-procedure were 4.3% (1/23), 0% and 0%, respectively. Conclusions: This study provides important preliminary data on safety and efficacy of perioperative LMWH bridging for adolescent VTE patients receiving warfarin. Larger collaborative pediatric studies are warranted to substantiate these findings and to investigate prognostic factors of bleeding and recurrent TE in this setting.
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