Anticoagulation in pregnant women with prosthetic heart valves

The combination of heart disease and pregnancy can present a formidable challenge to the clinician entrusted to care for both the mother and fetus. Since most data is retrospective, a definitive prognosis for such a patient may be difficult to obtain. Nevertheless, certain cardiac conditions carry greater risks of maternal mortality than do others. However, even for certain preexisting conditions, a tremendous amount of debate persists with respect to risks during pregnancy and optimal peripartum management. One such area of controversy concerns anticoagulation in pregnant women with prosthetic heart valves. For patients who require anticoagulation for mechanical valves, the choice of some combination of warfarin, unfractionated heparin, and low-molecular-weight heparin (LMWH) has resulted in many small-scale trials, which have not yet provided definite guidance as to the best course of action. Even more controversial has been the recent labeling change that advises against the use of LMWH in all patients with prosthetic heart valves, as a result of two cases of prosthetic valve thrombosis in women using LMWH while pregnant. Although the latest product labeling, in the summer of 2003, was changed to a less restrictive recommendation, debate persists. A discussion of the available data on anticoagulation in pregnant women with prosthetic heart valves is presented here, to inform the clinician and the patient of the risks and benefits of the options presently available.