OC 65.1 - Early Resolution of Neonatal and Infant Venous Thrombi: A Retrospective Review

Background: Neonates and infants who develop venous thromboembolism (VTE) are often treated with anticoagulation for up to 3 months. However, anticoagulation is not without risk, and treatment for the shortest duration to achieve clot resolution would be optimal. Previous studies suggest shorter courses of anticoagulation (i.e., ≤6weeks) are sufficient for thrombus resolution in children. Due to differences in developmental hemostasis, neonates/infants may require even shorter durations of therapy. Therefore, standard practice for KidClot/Stollery Children’s Hospital since 2003 has been to re-image patients aged ≤90days within 2 weeks of starting anticoagulation for VTE.

Aims: To review rates of thrombus resolution at ≤2weeks in neonates/infants (age ≤90days) treated by KidClot/Stollery Children’s Hospital.

Methods: A retrospective review of patients aged ≤90days with VTE treated by KidClot Jan/2003-Dec/2013 was conducted. Data was extracted for patients with ≥1 VTE and started on anticoagulation therapy. Patients without follow-up imaging onsite (e.g., transferred to another hospital/jurisdiction) and those with solely arterial, superficial vein, portal vein and/or renal vein thrombi were excluded. Data on patient age, provoking factor(s), anticoagulation type(s), thrombus size/location was collected. Outcomes included thrombus resolution on imaging within 3 months and long-term recurrence on up to 10-years post-therapy.

Results: In patients ≤90days, 41/87 had full and 19/87 had partial clot resolution by ≤3months of anticoagulation. In neonates ≤30days, 21.6% (8/37) had full resolution of VTE after 2weeks. Sub-analysis of VTE resolution based on provoking factor (e.g., central line), site of VTE (upper vs lower limb) are ongoing along with data on long-term recurrence on imaging up to 10-years post-therapy.

Conclusion(s): Results suggest a high rate (>20%) of VTE resolution within 2weeks of anticoagulation therapy for patients aged ≤30days. While further study is needed, this supports early follow-up imaging and cessation of anticoagulation may be warranted in this age group to reduce risks of anticoagulation.