An interventional study of LMWH and LDA and Vitamin K antagonists (e.g warfarin)+/- LDA in Pregnancy, Prosthetic Heart Valve and Anticoagulant Therapy, sponsored by Mount Sinai Hospital, Canada. Recruiting at 1 site in Canada. Open to female participants aged 18 Years to 45 Years. Per ClinicalTrials.gov, last updated 2026-06-22.
Sponsored by Mount Sinai Hospital, Canada · Not applicable, Interventional, and Treatment
The purpose of this pilot study is to collect data on pregnancies with mechanical heart valves to see if using a blood thinner called low molecular weight heparin (LMWH) and low dose aspirin (LDA) is comparable to warfarin/vitamin K antagonist (VKA) to reduce the chance of clotting around the mechanical valve and improve survival. The study is a pilot study as the study investigators need to ensure that the blood levels needed for adequate amounts of LMWH and warfarin can be maintained during pregnancy to be able to compare LMWH and aspirin to warfarin. If this study shows that we can collect the tests that are needed for a larger study, the individuals' information who participated in this pilot study will be moved to the larger study. The larger study will compare survival, clot development and cardiac function as well as safety of these two common blood thinners.
Pregnancies with mechanical heart valves (MHVs) have a substantial risk of thromboembolic events, hemorrhage, mortality and low live birth rates. The observational studies that have been published have been challenged by the lack of standardized regimens for antithrombotic agents (including standardized dosing and monitoring), standardized measurements of outcomes, and the observational nature. Notably, there are also limited data collected and described for maternal and neonatal safety and on cardiac morbidity such as left ventricular function (LVF) i.e., left ventricular ejection fraction, frequency of arrhythmias and valve competence after pregnancy. Individuals with MHVs are predominantly from low resource countries and optimizing maternal and fetal morbidity and mortality in these pregnancies should be prioritized similarly as other pregnancies. There is a need for a prospective controlled multicenter study as individual's centers do not have the patient volumes for risk assessment and many centers are in low resource settings. We will conduct a multicenter controlled prospective internal pilot pragmatic study comparing the two standard antithrombotic regimens (LMWH and LDA vs VKAs) for 100 pregnancies with MHVs. The sequential therapy regimen will be combined with the regimen of VKAs as most of the pregnancy is exposed to VKAs, but secondary analysis will be conducted separating the two groups. Patients will be recruited in obstetrical clinics before 12 weeks gestation.
The overall objective is to determine the optimal antithrombotic regimen for pregnancies with MHVs.
3.1 Primary Objective To assess feasibility of conducting a large prospective controlled (adherent to an anticoagulation regimen) study by determining
1) Enrollment rates a) patients enrolled/patients eligible, and b) consent rates (consent obtained/patients approached), 2) Protocol adherence, 3) Ability to accurately collect data and complete the eCRF, 4) Resources required for a larger study and, 5) To ensure accuracy of effect size as described above. 3.2 Secondary Objective(s) To determine the rate of
B. Presence of embryopathy/fetopathy secondary to VKAs C. Small for gestational age neonates less than the 10th percentile for gestational age and D. Need for neonatal critical care.
Mount Sinai Hospital, Canada is the lead sponsor of 157 studies on the registry; 33 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Therapeutic LMWH throughout pregnancy either using weight-based dosing or dosing according to peak and/or trough anti-Xa levels (measured after at least 4 days of starting or change of dose) and LDA
Drug: LMWH and LDA
VKA use will require INRs every two weeks or weekly (done at least 5 days after starting or changing the dose) if there is a change in doses to ensure an INR of 2.5 for and aortic MVR and 3 for a mitral MVR or two MHVs is met.
Other: Vitamin K antagonists (e.g warfarin)+/- LDA
LMWH at 6 weeks gestation until 12 weeks gestation prescribed according to the regimens above then VKAs from 12 weeks gestation until 34-36 weeks gestation followed by twice daily LMWH. VKA use will require INRs every two weeks or weekly (done at least 5 days after starting or changing the dose) if there is a change in doses to ensure an INR of 2.5 for an aortic MVR (INR of 2 for the On-X AVR) and 3 for mitral MVR or two MHVs is met. LMWH will be administered twice daily according to pregnancy weight or anti-Xa level
Other: Sequential therapy +/- LDA
1\) Therapeutic LMWH throughout pregnancy either using weight-based dosing or dosing according to anti-Xa levels. The initial dose will be a twice daily therapeutic dose of 1.35U/kg (pregnancy weight) of enoxaparin or 135 U/kg (pregnancy weight) of dalteparin using prefilled syringes titrated to the higher dose prefilled syringe (i.e., not below the pregnancy weight-based dosing). 1. The dose of therapeutic LMWH can be adjusted by anti-Xa (done at least after four days of the start of LMWH or change in LMWH dose) levels or by pregnancy weight however, weight and anti-Xa levels will be determined for all participants using LMWH. Pregnancy weight in kilograms is to be determined every month. 2. If therapeutic LMWH is adjusted according to anti-Xa levels, peak and trough anti-Xa levels (done at least after four days of the start of LMWH or change in LMWH dose) are to be sent every four weeks or weekly if there is a change in dose.
VKAs during pregnancy: VKA use will require INRs every two weeks or weekly (done at least 5 days after starting or changing the dose) if there is a change in doses to ensure an INR of 2.5 for a patient with an aortic MVR (INR of 2 for the On-X AVR) and 3 for mitral MVR or two MHVs is met. LDA 81 mg to be added once pregnancy is confirmed.
LMWH at 6 weeks gestation until 12 weeks gestation prescribed according to the regimens above then VKAs from 12 weeks gestation until 34-36 weeks gestation followed by twice daily LMWH according to doses above until delivery. LDA to be added when pregnancy is confirmed
Also known as: LMWH, Vitamin K antagonist, warfarin
Primary outcome Measures
1\) Enrollment rate: To determine enrollment rate as defined by the number of patients enrolled/patients eligible, and consent rates (consent obtained/patients approached)
Time frame: At baseline
Adherence rate
To determine the adherence rate as defined as adherence to the anticoagulation regimen in 80% or more of the pregnancy.
Time frame: From enrollment until birth.
Secondary outcome measures
A composite outcome of all-cause mortality rate according to gestational age and maternal valve thrombosis rate
Time frame: From enrollment until 12 weeks postpartum
Plan to share: Undecided
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Mount Sinai Hospital, Canada