VPB1381 - A Case Series In Pregnant Women Receiving Therapeutic LMWH, Is Monitoring Anti-Xa Levels Necessary?

Background: Pregnancy increases the risk of thrombosis. It's a constant issue for treating doctors since it raises the risk of venous thromboembolism (VTE) and valve thrombosis in women who have mechanical heart valves (MHV). The dosage of low molecular weight heparin (LMWH) is usually determined by weight, but the management of LWMH dosage during pregnancy is debatable. Some research imply that dose adjustments should be monitored with anti-Xa levels, while others argue that weight-based dosing eliminates the need for adjustments.

Aims: The anti-Xa level in MHV and VTE patients was the main focus of our investigation. Secondly, we compared their actual LMWH dosing and dosage adjustments in both groups based on anti-Xa levels.

Methods: This is a retrospective cohort between 2020 and 2021 of all pregnant women who were therapeutically anticoagulated with LMWH and had anti-Xa levels of at least 1 peak (+/- trough) antenatally.

Results: During the study period, 4 (80.0%) of the women with MHV (N=5) were kept on the same LMWH dosage throughout the antenatally, whereas 1 (20.0%) required dose modifications based on trough and peak anti-Xa levels. 4 (57.1%) of the women with VTE (N=7) showed subtherapeutic levels of peak anti-Xa in the VTE group. However, the dosage was not changed throughout pregnancy. LMWH therapy did not cause any bleeding or clotting issues. No reports of maternal thrombotic complications were identified.

Conclusion(s): In pregnant women with high risk such as MHV and VTE, monitoring by trough and peak anti-Xa levels maybe be use for dosage guidance on a case-by-case basis. However a well-designed prospective trial evaluating the effect of anti-Xa monitoring strategies on clinically important outcomes is needed.