Anticoagulant management of pregnancy following heart valve replacement in the United Kingdom, 1986-2002.
OBJECTIVE
Patients with mechanical heart valves require anticoagulation which is associated with significant maternal mortality (1-4%) and fetal complications (31%) in pregnancy. The study aim was to identify anticoagulant protocols and outcomes for pregnant women undergoing heart valve replacement (HVR) in the United Kingdom.


METHODS
Women aged between 18 and 45 years and registered with the United Kingdom Heart Valve Registry (UKHVR) each completed a questionnaire, and their obstetric notes were reviewed. The data analyzed included valve type (mechanical, bioprosthetic, homograft), valve site (mitral, aortic, tricuspid, pulmonary), anticoagulation at confirmation of pregnancy, between 6-12 weeks and from 12 weeks to term, delivery, maternal and fetal outcomes, and cause of death. The summary statistics and a descriptive review of the findings are reported.


RESULTS
Of 2,532 women eligible for the study, 922 responded. Among these women, 72 became pregnant, with 60 pregnancies in the mechanical valve (MV) group and 45 in the tissue valve (TV) group. Three anticoagulation regimes were used during early pregnancy: unfractionated heparin (UFH), low-molecular-weight heparin (LMWH) or warfarin. All women received warfarin in the second trimester and heparin for delivery. Live births were recorded in 30% of MV pregnancies and in 60% of TV pregnancies. Miscarriage rates differed markedly (37% MV versus 2% TV). Fetal outcome was poorest in the warfarin-only group, with embryopathy occurring at a dose level of 6 mg. The maternal outcomes did not differ significantly among groups. High-dose heparin during the first trimester and for delivery was effective for the majority of mechanical valves.


CONCLUSIONS
The study results illustrate the diverse and uncertain manner in which UKHVR patients are managed during pregnancy. A national notification system would record much-needed prospective information on anticoagulation and pregnancy outcomes, thus aiding evidence-based management.
Shannon
Muriel S
MS
Department of Haematology, St. George's Hospital, London. mshannon@sgul.ac.uk
Edwards
Maria-Benedicta
MB
Long
Fiona
F
Taylor
Kenneth M
KM
Bagger
Jans Peder
JP
De Swiet
Michael
M
D000022:Abortion, Spontaneous / Q000401:mortality; D000293:Adolescent; D000328:Adult; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D001705:Bioprosthesis; D002423:Cause of Death; D004305:Dose-Response Relationship, Drug; D005260:Female; D005315:Fetal Diseases / Q000139:chemically induced / Q000401:mortality; D006333:Heart Failure / Q000401:mortality; D019918:Heart Valve Prosthesis Implantation; D006493:Heparin / Q000009:adverse effects / Q000627:therapeutic use; D006495:Heparin, Low-Molecular-Weight / Q000009:adverse effects / Q000627:therapeutic use; D006801:Humans; D008875:Middle Aged; D011183:Postoperative Complications / Q000188:drug therapy* / Q000401:mortality; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000188:drug therapy* / Q000401:mortality; D011256:Pregnancy Outcome; D012307:Risk Factors; D006113:United Kingdom; D014859:Warfarin / Q000009:adverse effects / Q000627:therapeutic use
D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight; D014859:Warfarin; D006493:Heparin