A 35-year-old woman comes to the office as she missed her period 10 days ago and believes that she may be pregnant. She otherwise has regular monthly menstrual cycles. The patient moved to the United States from South Africa 6 months ago, and has a history of rheumatic heart disease. She had a "ministroke" 8 years ago and was found to be in atrial fibrillation at that time; she has since been on warfarin for anticoagulation. The patient took antibiotic prophylaxis for secondary prevention of rheumatic fever with intramuscular penicillin until age 30.
Temperature is 37.2 C (99 F), blood pressure is 122/82 mm Hg, pulse is 96/min, and respirations are 14/min. The lungs are clear to auscultation. Cardiac examination reveals irregular heart sounds, an accentuated S1, and a loud "snapping" sound shortly after S2. There is also a faint mid-diastolic murmur heard over the cardiac apex.
Urine pregnancy test is positive. ECG is shown in the exhibit.
Which of the following is the best next step in management of this patient?

Question

A 35-year-old woman comes to the office as she missed her period 10 days ago and believes that she may be pregnant.  She otherwise has regular monthly menstrual cycles.  The patient moved to the United States from South Africa 6 months ago, and has a history of rheumatic heart disease.  She had a "ministroke" 8 years ago and was found to be in atrial fibrillation at that time; she has since been on warfarin for anticoagulation.  The patient took antibiotic prophylaxis for secondary prevention of rheumatic fever with intramuscular penicillin until age 30.
Temperature is 37.2 C (99 F), blood pressure is 122/82 mm Hg, pulse is 96/min, and respirations are 14/min.  The lungs are clear to auscultation.  Cardiac examination reveals irregular heart sounds, an accentuated S1, and a loud "snapping" sound shortly after S2.  There is also a faint mid-diastolic murmur heard over the cardiac apex.
Urine pregnancy test is positive.  ECG is shown in the exhibit.
Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

This patient, who has a history of rheumatic heart disease and physical examination findings of an accentuated S1, a loud "snapping" sound after S2 (opening snap), and a mid-diastolic murmur, has rheumatic mitral stenosis. Atrial fibrillation in the setting of mitral stenosis is associated with high thromboembolic risk, and this patient should continue anticoagulation therapy throughout pregnancy. Low-molecular-weight heparin (LMWH) is recommended in such patients until the final few weeks of pregnancy, at which time therapy is often transitioned to unfractionated heparin (UFH) for easier reversibility during labor and delivery. Both LMWH and UFH are not associated with teratogenicity and do not cross the placental barrier to cause fetal anticoagulation. (Choice A) Warfarin is associated with teratogenicity (eg, skeletal abnormalities) and can cross the placental barrier, leading to fetal bleeding. Low-dose warfarin <5 mg/day appears to provide a higher safety margin, and continuing this regimen throughout pregnancy (including the first trimester) is a potential option for pregnant patients with mechanical heart valves. However, pregnant patients with any other indication for anticoagulation (eg, atrial fibrillation, venous thromboembolism) and those with higher dose requirements (>5 mg/day) should be managed with subcutaneous LMWH. < (Choice B) This patient is at high risk for systemic thromboembolism during pregnancy and requires anticoagulation. Monitoring without anticoagulation would not be appropriate. (Choice C) Oral direct thrombin inhibitors (eg, dabigatran) and factor Xa inhibitors (eg, apixaban, rivaroxaban, edoxaban) are not indicated in patients with valvular atrial fibrillation. Furthermore, these drugs do not have adequate safety and efficacy information for use during pregnancy. (Choice D) Subcutaneous UFH every 12 hours (not daily) is indicated for anticoagulation during pregnancy in patients with severe renal insufficiency (creatinine clearance <30 mg/mL). However, when possible, the use of LMWH is preferred due to the lower risk of heparin-induced thrombocytopenia. Educational objective: Warfarin can cross the placental barrier and is associated with fetal bleeding and risk of teratogenicity when used during pregnancy. With the possible exception of patients on low-dose warfarin for a mechanical heart valve, all others who require anticoagulation during pregnancy should be switched to low-molecular-weight or unfractionated heparin. __________ References: VTE, thrombophilia, antithrombotic therapy, and pregnancy: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. (http://www.ncbi.nlm.nih.gov/pubmed/22315276) Risk of warfarin during pregnancy with mechanical valve prostheses. (http://www.ncbi.nlm.nih.gov/pubmed/11777507)

A 35-Year-Old Woman Comes to the Office as She Missed