Anticoagulation for the Pregnant Patient with a Mechanical Heart Valve, No Perfect Therapy: Review of Guidelines for Anticoagulation in the Pregnant Patient

Table 1

ACC/AHA anticoagulation guidelines for pregnant patients with mechanical heart valves.

Class I	Class IIa	Class IIb	Class III
A therapeutic INR of 2-3 (INR of 2.5–3.5 for mitral valves) for all patients prescribed a VKA	Continue VKA during first trimester in pregnant patients if dose to achieve therapeutic INR is 5 mg per day or less with full discloser of risks	If daily warfarin dose less than or equal to 5 mg a day to achieve therapeutic INR, adjusted LMWH at least two times a day with target anti-Xa level of 0.8 IU/ml to 1.2 IU/ml 4 to 6 hours after administration may be used during first trimester of pregnancy	LMWH should not be administered unless anti-Xa levels are monitored 4 to 6 hours after administration.
In pregnant patients, warfarin may be used to achieve therapeutic INR in second and third trimesters	LMWH at least two times a day with target anti-Xa level of 0.8 IU/ml to 1.2 IU/ml 4 to 6 hours after administration during first trimester if daily warfarin dose greater than 5 mg per day for therapeutic INR	Dose adjusted continuous intravenous UFH with aPTT at least 2 times greater than control for pregnant patients with warfarin dose less than or equal to 5 mg a day for therapeutic INR during the first trimester	—
Discontinue VKA and initiate IV UFH with activated partial thromboplastin time (aPTT) greater than two times the control before planned vaginal delivery	Adjusted continuous intravenous UFH with aPTT at least 2 times greater than control for pregnant patient if daily warfarin dose greater than 5 mg a day for therapeutic INR	—	—
Add low-dose aspirin (75 mg to 100 mg) during second and third trimesters	—	—	—

Class I: treatment should be performed or administered. Class IIa: it is reasonable to perform procedure or administer treatment. Additional studies with focused objectives needed. Class IIb: procedure or treatment may be considered. Additional studies with broad objectives needed. Class III: procedure or treatment should not be performed or administered since it is not helpful and may be harmful.