What is the recommended treatment for a pregnant woman with a grade 4 patent foramen ovale (PFO) who experienced a stroke, using Lovenox (enoxaparin)?

From the Guidelines

For a pregnant woman with a grade 4 patent foramen ovale (PFO) who experienced a stroke, the recommended treatment is therapeutic-dose Lovenox (enoxaparin) throughout pregnancy, with a typical dosing of 1 mg/kg subcutaneously twice daily and potential dose adjustments based on anti-Xa levels (target range 0.6-1.0 IU/mL) 1.

Key Considerations

• The treatment should continue throughout pregnancy and be transitioned to unfractionated heparin at 36 weeks gestation in preparation for delivery.
• Postpartum, the patient should be transitioned to warfarin with a target INR of 2.0-3.0 for at least 3-6 months, with consideration for longer anticoagulation or PFO closure depending on stroke recurrence risk.
• Lovenox is preferred during pregnancy as it doesn't cross the placenta, unlike warfarin which is teratogenic.
• Regular monitoring of platelet counts and anti-Xa levels is essential, and the patient should be managed by a multidisciplinary team including maternal-fetal medicine, neurology, and cardiology specialists.

Rationale

The approach is recommended because pregnancy creates a hypercoagulable state that increases stroke risk, and the grade 4 PFO (large size with significant right-to-left shunting) represents a substantial risk for paradoxical embolism.

Monitoring and Management

• Monitoring of anti-Xa levels is crucial to ensure the patient is within the therapeutic range, and dose adjustments should be made accordingly 1.
• The patient should be closely monitored for signs of thrombocytopenia, and platelet counts should be regularly checked.
• A multidisciplinary team approach is necessary to manage the patient's care, including maternal-fetal medicine, neurology, and cardiology specialists.

Additional Considerations

• PFO closure may be considered postpartum, depending on the patient's individual risk factors and stroke recurrence risk 1.
• The decision to pursue PFO closure should be made on a case-by-case basis, taking into account the patient's overall health and medical history.

From the Research

Lovenox Treatment for Grade 4 PFO in Pregnancy

• The recommended dose of Lovenox (enoxaparin) for pregnant women with a grade 4 patent foramen ovale (PFO) who experienced a stroke is not explicitly stated in the provided studies, but a therapeutic dose of 1 mg/kg subcutaneously twice daily is mentioned in the study by 2.
• The duration of Lovenox treatment is not specified in the provided studies, but it is implied that treatment should continue throughout pregnancy and possibly postpartum, as the risk of stroke is elevated during this period 3.
• Monitoring of anti-factor Xa levels is recommended to ensure therapeutic levels are maintained, as fluctuations in levels can occur during pregnancy 2.
• The study by 4 suggests that doses should be normalized for body weight changes to counteract enoxaparin pharmacokinetic changes that accompany various stages of pregnancy.
• It is also important to note that enoxaparin does not cross the placenta and is safe for the fetus, with uncommon maternal side effects including mild localized allergic reactions and increased bleeding 5.

Considerations for Treatment

• The risk of ischemic stroke is elevated especially from the third trimester until 6 weeks postpartum, and multidisciplinary care is essential when counseling these women in the acute and later stages 3.
• Reperfusion therapies should not be withheld from a pregnant woman with moderate-to-severe stroke when benefits outweigh the risk 3.
• Aspirin up to 150 mg daily is considered well tolerated during pregnancy and lactation period 3.

Pharmacokinetics and Pharmacodynamics

• The study by 4 found that clearance of enoxaparin was higher in pregnant women throughout pregnancy compared to nonpregnant women, and the volume of distribution was influenced by stage of pregnancy.
• The study by 2 found that mean anti-factor Xa activity levels were therapeutic at peak, but sub-therapeutic at trough and 8-h post-dose in a substantial number of patients receiving a twice daily regimen of therapeutic enoxaparin.