Monitoring of Anti-Xa in Pregnant Patients With Mechanical Prosthetic Valves Receiving Low-Molecular-Weight Heparin

Abstract

Anticoagulation with adjusted dose LMWH aimed to achieve guideline-recommended peak levels of anti-Xa for patients with MPHVs is commonly associated with subtherapeutic trough levels. Routine measurement of trough anti-Xa levels is therefore advisable in women with MPHV treated with LMWH during pregnancy to assure adequate level of anticoagulation.

Management of Pregnancy in Patients With Complex Congenital Heart Disease: A Scientific Statement for Healthcare Professionals From the American Heart Association

“…The measurement of trough levels may also be helpful, although data are scant. [153][154][155] In addition to anticoagulants, all pregnant women with mechanical valves should receive low-dose aspirin (75-100 mg once a day).…”

Optimal Anticoagulation for Pregnant Women with Mechanical Heart Valves

“…When used, UFH is adjusted to increase the activated partial thromboplastin time to two to three times the baseline. LMWHs are also usually dose adjusted to target peak anti-factor Xa (FXa) levels of 0.8 to 1.2 IU/mL 7,8 although some authors have suggested that levels of up to 1.5 IU/mL may be acceptable. 9 There are also increasing calls to use trough anti-FXa levels (0.6-0.8 IU/mL) to guide therapeutic efficacy.…”

“…9 There are also increasing calls to use trough anti-FXa levels (0.6-0.8 IU/mL) to guide therapeutic efficacy. [7][8][9] LMWH is preferred over UFH due to its more predictable anticoagulant effect as well as concerns over the increased risks of heparininduced thrombocytopenia and osteoporosis with UFH. 10 However, LMWH is expensive in some countries and cost may be important factor to consider for some women.…”

Anticoagulation in pregnancy and puerperium: With a focus on the benefits and risks of the applications of vitamin K antagonists on the prevention of mechanical heart valves thrombosis

“…Th e increasing use of LMWH (recommended by current guidelines but not yet offi cially indicated for the prevention of thrombosis of mechanical valves in the summaries of the drug characteristics) requires treatment with therapeutic doses, determined based on periodic monitoring of the anti-Xa activity (measurements of peak anti-Xa levels mandatory, it also being possible in specifi c cases to measure through anti Xa activity levels) [23][24][25][26][27][28][29].…”

“…More recent research suggests that along with peak anti-Xa activity there should also be monitored trough (lowest) levels of anti-Xa activity [24]. It is known that pregnant women receiving enoxaparin every 12h with peak anti-Xa levels of 0.7-1.2 U/ mL are associated with sub-therapeutic trough levels, with a pre-dose level of less than 0.6 IU/ mL in over 50% of cases [24][25][26][27].…”