[Mechanic valve prosthesis and pregnancy: Is Phenprocoumon replaceable?].

Area of Science:

• Cardiology
• Obstetrics
• Pharmacology

Background:

• A 30-year-old pregnant patient with a history of rheumatic fever underwent mechanical aortic and mitral valve replacement 12 years prior.
• The patient had experienced multiple prior complications including mitral valve thrombosis, reoperation, and recurrent thrombosis treated with thrombolysis, likely due to non-compliance.
• Previous pregnancies resulted in three abortions.

Observation:

• The patient self-discontinued Phenprocoumon (a coumarin derivative) at 5+4 weeks gestation.
• Vaginal sonography confirmed an intact gestation; however, laboratory tests showed an INR of 1.2.
• Transesophageal echocardiography revealed a partially thrombosed mechanical mitral valve, and abdominal ultrasonography detected an embolic splenic infarction.

Findings:

• The clinical presentation was consistent with a partially thrombosed mechanical mitral valve and thromboembolic splenic infarction secondary to inadequate oral anticoagulation.
• Initial management involved heparinization, followed by restarting Phenprocoumon (target INR 2.5-3.5) with aspirin.
• The patient subsequently experienced a missed abortion, necessitating curettage under therapeutic intravenous heparinization.

Implications:

• Coumarin anticoagulants (e.g., Phenprocoumon) pose fetal risks during pregnancy but are considered the most secure option for anticoagulation after mechanical valve replacement, particularly in high-risk patients.
• Heparin anticoagulation is a viable alternative, as it does not cross the placenta, though it carries a slightly increased risk of thromboembolism.
• Careful consideration of anticoagulation strategies is crucial in pregnant patients with mechanical heart valves to balance maternal thrombotic risk and fetal safety.