Optimizing Anticoagulation in Pregnancies With Mechanical Heart Valves

NCT07658989 | Recruiting DMC

• 2 other identifiers: MVR2210245377
• Study Type: interventional
• Target: 100
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Pregnancy; Prosthetic Heart Valve; Anticoagulant Therapy

Keywords

Pregnancy; Prosthetic heart valve; Anticoagulant therapy; Low molecular weight heparin; warfarin; vitamin K antagonist

Outcome Measures

Primary Outcomes (2)

• 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)

  At baseline

• Adherence rate

  To determine the adherence rate as defined as adherence to the anticoagulation regimen in 80% or more of the pregnancy.

  From enrollment until birth.

Secondary Outcomes (1)

• Secondary outcome measures

  From enrollment until 12 weeks postpartum

Study Arms (3)

LMWH and LDA

EXPERIMENTAL

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

Vitamin K antagonists (e.g warfarin)+/- LDA

OTHER

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

Sequential therapy +/-LDA

OTHER

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

Interventions

LMWH and LDA DRUG

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.

LMWH and LDA

Vitamin K antagonists (e.g warfarin)+/- LDA OTHER

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.

Vitamin K antagonists (e.g warfarin)+/- LDA

Sequential therapy +/- LDA OTHER

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

Sequential therapy +/-LDA

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Pregnant individuals with one or more MHVs
• Who consent to participate
• Are 18 years or older and
• Less than 12 weeks gestation

You may not qualify if:

• Have a platelet count less than 50 x 10(9)/L as there is an increased risk of bleeding with thrombocytopenia, and/or
• Have active bleeding defined as bleeding resulting in a hemoglobin reduction ≥10 g/L or in hemodynamic instability.
• Have new valve thrombosis identified immediately prior to pregnancy

Sponsors & Collaborators

• Mount Sinai Hospital, Canada: lead

Study Sites (1)

Mount Sinai Hospital

Toronto, Ontario, M5G1X5, Canada

RECRUITING

MeSH Terms

Interventions

Heparin, Low-Molecular-Weight; acarboxyprothrombin; Warfarin

Intervention Hierarchy (Ancestors)

Heparin; Glycosaminoglycans; Polysaccharides; Carbohydrates; 4-Hydroxycoumarins; Coumarins; Benzopyrans; Pyrans; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring

Central Study Contacts

Nadine Shehata, MD

CONTACT

4165865133; nadine.shehata@sinaihealth.ca

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: November 26, 2025
• First Posted: June 22, 2026
• Study Start: May 26, 2026
• Primary Completion (Estimated): January 1, 2030
• Study Completion (Estimated): December 1, 2030
• Last Updated: June 22, 2026

Record last verified: 2026-05

Locations

CA (1)