Need for Antepartum Thromboprophylaxis in Pregnant Women With One Prior Episode of Venous Thromboembolism (VTE)

Study Overview
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Brief Summary
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Pregnant women with a prior history of venous thromboembolism (VTE) are at increased risk of recurrent VTE. Current guidelines assessing the role of prophylaxis in pregnant women with prior VTE are based primarily on expert opinion and the optimal clinical management strategy remains unclear. This multicentre, prospective cohort study aims to test the following hypotheses: Antepartum prophylaxis with fixed-dose low molecular-weight heparin (LMWH) is safe, convenient and associated with an acceptably low risk of recurrent VTE in women with a single prior episode of VTE that was either unprovoked or associated with a minor transient risk factor. (Moderate risk cohort) Withholding antepartum prophylaxis is safe (recurrence risk <1%) in pregnant women with a single prior episode of VTE provoked by a major transient risk factor. (Low risk cohort) All study patients will receive 6 weeks of postpartum prophylaxis.

Official Title
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Prospective Study Assessing the Need for Antepartum Thromboprophylaxis in Pregnant Women With One Prior Episode of Venous Thromboembolism

Conditions
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Venous Thromboembolism, Deep Vein Thrombosis, Pulmonary Embolism

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Confirmed pregnancy (positive serum or urine) At least 18 years of age History of one prior episode of VTE consisting of DVT (diagnosed by compression ultrasonography [CUS] or venography) and/or PE (diagnosed by ventilation-perfusion [V/Q] lung scintigraphy, computed tomographic pulmonary angiography [CTPA], or traditional pulmonary angiography) Exclusion Criteria: Ongoing need for therapeutic anticoagulation for prevention or treatment of cardioembolic stroke Known high-risk thrombophilia (specifically antithrombin deficiency, protein S deficiency, protein C deficiency, homozygosity for the factor V Leiden or prothrombin G20210A mutations, antiphospholipid antibody or compound abnormalities) VTE within 3 months of the current pregnancy Clinical risk factor for initial episode of VTE, if present, not resolved (excluding pregnancy) Known contraindication to anticoagulation (including active, uncontrolled bleeding or major bleed within the previous 4 weeks) For patients with prior unprovoked VTE, contraindication to LMWH (including allergy, HIT, impaired renal function, osteoporosis) Geographic or social factors precluding follow-up Inability or unwillingness to provide informed consent

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Prior VTE minor transient risk factor<br>Pregnant women with a single prior VTE episode that was either unprovoked or associated with a minor transient risk factor - Prophylaxis with fixed-dose LMWH | |
| Prior VTE major transient risk factor<br>Pregnant women with a single prior VTE episode that was provoked by a major transient risk factor - Surveillance | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Symptomatic venous thromboembolism | Symptomatic objectively confirmed recurrent VTE, including proximal DVT, non-fatal PE, and fatal PE during antepartum period | antepartum period (expected average 7 months) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Symptomatic recurrent venous thromboembolism | Symptomatic recurrent VTE antepartum and within first 3 months postpartum | antepartum period (expected average 7 months) and first 3 months postpartum | 
| Symptomatic recurrent pulmonary embolism | Symptomatic objectively confirmed recurrent PE antepartum and within first 3 months postpartum | antepartum period (expected average 7 months) and first 3 months postpartum | 
| Thrombocytopenia or heparin-induced thrombocytopenia (HIT) | Thrombocytopenia or HIT during antepartum period | antepartum period (expected average 7 months) | 
| Symptomatic osteoporosis | Symptomatic osteoporosis antepartum and within first 3 months postpartum | antepartum period (expected average 7 months) and first 3 months postpartum | 
| Other complications | Other complications sufficient to stop treatment (e.g., local and systemic reactions) antepartum and within first 3 months postpartum | antepartum (expected average 7 months) and within first 3 months postpartum | 
| Pregnancy complications and outcomes | Pregnancy complications and outcomes including fetal death, pre-eclampsia, toxemia, intrauterine growth restriction, prematurity during antepartum period | antepartum period (expected average 7 months) | 
| Fetal anomalies | Fetal anomalies | antepartum (expected average 7 months) and during first 3 months postpartum | 
| Major and minor bleeding | Major and minor bleeding | antepartum (expected average 7 months) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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venous thromboembolism, thromboembolism, deep vein thrombosis, pulmonary embolism, thromboprophylaxis, thrombosis, embolism and thrombosis, cardiovascular diseases, venous thrombosis, vascular diseases, anticoagulants, hematologic agents, cardiovascular agents, enoxaparin, dalteparin, tinzaparin, pregnancy complications