The effectiveness and side effects of anti-coagulant drugs in pregnant women with mechanical or bio-prosthetic heart valves: A systematic review and meta-analysis study.

Background and objectives: Patients with pregnancy and mechanical or bio-prosthetic heart valves (BHVs) need tailored antithrombotic therapy to prevent thromboembolism. The goal of this study was to evaluate the effects and complications of various anticoagulation strategies used during pregnancy in these patients using a meta-analysis.

Method: We searched PubMed, Google Scholar, Scopus, EMBASE, and Web of Science databases and discovered 24 articles. We also discarded some articles when evaluating them in detail due to inadequate information. Finally, 24 studies were included in the systematic review. We compared pregnancy outcomes in three groups of pregnant women: 1) Those taking warfarin; 2) Those taking LMWH (Low Molecular Weight Heparin) or UFH (Unfractionated Heparin); 3) Those on no anticoagulant therapy. The authors would like to thank the Clinical Research Development Unit (CRDU) of Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran for their support, cooperation and assistance throughout the period of study. The ethic code is: IR.SBMU.RETECH.REC.1403.831.

Results: The incidence of maternal thromboembolic events was higher in the UFH or LMWH group, but fetal complications (FC) were lower in this group. Using warfarin during the first trimester was associated with a higher abortion rate, embryopathies, and FCs overall. Using <5 mg of warfarin daily to maintain their targeted INR had a lower risk of developing. Preterm labor and spontaneous abortion were observed in 0.09 (95 % CI = 0.04-0.14) and 0.08 (95 % CI = 0.01-0.14) of cases in the LMWH/UFH subgroup. In terms of maternal complications (MCs) in Warfarin subgroup, maternal hemorrhagic complications, maternal thromboembolic events, and valve thrombosis were respectively observed in 2.0 (95 % CI = 0-3), 0.01 (95 % CI = 0.00-0.03), 0.01 (95 % CI = 0.00-0.03); in LMWH subgroup the rates were 0.18 (95 % CI = 0.09-0.27), 0.03 (95 % CI = 0.00-0.06), and 0.28 (95 % CI = 0.15-0.71); and finally in those taking no anticoagulant therapy, the rates were 0.02 (95 % CI = 0.03-0.06), 0.07 (95 % CI = 0.06-0.19).

Conclusions: According to the results, preterm labor is a significant fatal complication in pregnant women on warfarin. Maternal hemorrhagic complications and thromboembolic events occur in the LMWH subgroup. There are no significant differences in other complications between the three subgroups.