The efficacy of low molecular weight heparin in the prevention of thromboembolic disease in pregnant patients with mechanical prosthetic heart valves.

Objective: To determine whether dosage adjustment of enoxaparin during pregnancy, in order to maintain a peak anti-Xa of 1.0-1.2 U/ml, is safe for women with mechanical prosthetic heart valves (MPHV). Methods: This was a prospective observational study performed at Charlotte Maxeke Johannesburg Academic Hospital from 2007 to 2009. 15 women with MPHVs were treated with enoxaparin with dosage adjustment throughout pregnancy to achieve a peak anti-Xa of 1.0-1.2 U/ml. Main outcomes measured were prosthetic valve thrombosis, bleeding and maternal mortality. Results: There was no maternal mortality. None of the women developed valvular thrombosis during pregnancy. Two women developed epistaxis and another developed spotting per vagina. There was no foetal mortality. Conclusion: Our data show that enoxaparin may be administered safely during pregnancy to pregnant women with mechanical prosthetic heart valves when there is dosage adjustment throughout pregnancy in order to maintain an anti-Xa of 1.0-1.2 U/ml.