Letter to the Editor: The use of low molecular weight heparin during pregnancy in patients with mechanical heart valves carries potential risk for valve thrombosis

Mechanical heart valves pose a particular challenge in pregnancy, as the primary agent used to prevent valve thrombosis, coumadin (warfarin), is a known teratogen. Alternatives to coumadin, such as unfractionated heparin (UFH) and low-molecular weight heparin (LMWH) are safer for the fetus, particularly during the first trimester of pregnancy, but expose the mother to potential valve failure. This review will examine these controversies and the complex literature regarding management in pregnancy.

Download Full-text

Efficacy and safety of low molecular weight heparin in patients with mechanical heart valves: systematic review and meta-analysis

Journal of Thrombosis and Haemostasis ◽

10.1111/jth.12544 ◽

2014 ◽

Vol 12 (5) ◽

pp. 650-659 ◽

Cited By ~ 10

Author(s):

D. Caldeira ◽

C. David ◽

A. T. Santos ◽

J. Costa ◽

F. J. Pinto ◽

...

Keyword(s):

Systematic Review ◽

Molecular Weight ◽

Low Molecular Weight Heparin ◽

Heart Valves ◽

Meta Analysis ◽

Mechanical Heart Valves ◽

Low Molecular Weight ◽

Efficacy And Safety

Download Full-text

Low-molecular-weight heparin or warfarin for anticoagulation in pregnant women with mechanical heart valves: what are the risks? A retrospective observational study

BJOG An International Journal of Obstetrics & Gynaecology ◽

10.1111/j.1471-0528.2012.03359.x ◽

2012 ◽

Vol 119 (8) ◽

pp. 1008-1013 ◽

Cited By ~ 48

Author(s):

S Basude ◽

C Hein ◽

SL Curtis ◽

A Clark ◽

J Trinder

Keyword(s):

Molecular Weight ◽

Observational Study ◽

Pregnant Women ◽

Low Molecular Weight Heparin ◽

Heart Valves ◽

Mechanical Heart Valves ◽

Retrospective Observational Study ◽

Low Molecular Weight

Download Full-text

Low molecular weight heparin for the prophylaxis of thromboembolism in women with prosthetic mechanical heart valves during pregnancy

Thrombosis and Haemostasis ◽

10.1160/th04-06-0337 ◽

2004 ◽

Vol 92 (10) ◽

pp. 747-751 ◽

Cited By ~ 95

Author(s):

Aviva Lee-Parritz ◽

ack Ansell ◽

Betul Oran

Keyword(s):

Molecular Weight ◽

Low Molecular Weight Heparin ◽

Heart Valves ◽

Factor Xa ◽

Thromboembolic Complication ◽

Mechanical Heart Valves ◽

Fixed Dose ◽

Low Molecular Weight ◽

Promising Alternative ◽

Prosthetic Valves

SummaryIncreased thromboembolic events occur in women with mechanical prosthetic valves during pregnancy, and selecting an effective and safe anticoagulant is still a challenge. Low molecular weight heparin (LMWH) is a promising alternative, but a recent warning and label change about its use in patients with mechanical prosthetic valves has caused confusion among physicians. The aim of the present study was to review the risks of maternal and fetal complications with mechanical heart valves treated with LMWH during pregnancy. We performed a review of the current medical literature through MEDLINE and EMBASE (1989 to 2004). Additional data sources included abstract proceedings, and reference lists of selected articles. Among 81 pregnancies in 75 women, the proportion of valve thrombosis was 8.64% (7/81; 95% CI, 2.52%–14.76%). The frequency of overall thromboembolic complication (TEC) was 12.35% (10/81; 95% CI, 5.19%–19.51%). Nine of ten patients with TEC received a fixed dose of LMWH and two of these received a fixed low dose of LMWH. Among 51 pregnancies whose anti-factor Xa levels were monitored, only one patient was reported to have a thromboembolic complication. The frequency of live births with LMWH was 87.65% (95%CI, 80.49%94.81%). In pregnant women with mechanical heart valves, LMWH appears to be a suitable option to a vitamin K antagonist. The use of LMWH warrants monitoring and appropriate dose adjustments to maintain a 4–6 hr post-injection anti-factor Xa level at a minimum of 1.0 U/ml to decrease the incidence of TEC.

Download Full-text