Low Molecular Weight Heparin Treatment in Pregnant Women with a Mechanical Heart Valve Prosthesis

Abstract

No definitive recommendation is available concerning optimal antithrombotic therapy in pregnant women with a mechanical heart valve. The purpose of the current study was to evaluate the clinical results of nadroparin treatment with respect to pregnancy outcome and maternal complications. From 1997 to 2005, 31 pregnancies were reviewed in 25 women. Nadroparin (7,500 U, twice daily) was used in 23 pregnancies between 6 and 12 weeks of gestation and close-to-term only, and coumarin derivatives were used with aspirin at other times. Eight pregnant women treated with coumarin derivatives throughout pregnancy were compared to evaluate the safety and efficacy of nadroparin. No maternal death or bleeding complication occurred in either of the two groups, and frequencies of maternal thromboembolism including valve thrombosis (8.7% vs. 12.5%, p>0.05) were similar. However, the frequencies of live born (91.3% vs. 50%, p=0.01) and healthy babies (90.4% vs. 25%, p<0.01) were significantly higher, and the fetal loss rate was significantly lower (8.7% vs. 50%, p=0.01) in the nadroparin-treated group. Regarding the efficacy and safety of antithrombotic treatment in pregnant women with prosthetic heart valves, nadroparin treatment during the first trimester is an acceptable regimen and produces better results than coumarin derivatives.

Prosthetic heart valves in pregnancy, outcomes for women and their babies: a systematic review and meta‐analysis

“…27 There were seven retrospective studies, two population-based cohort studies, 20,21 two multicentre unselected case series 28,32,33 and three single-centre unselected case series 28,30,31 (Table 1). Ten studies captured a total of 305 women undertaking 392 pregnancies.…”

“…Eight of the 11 studies allowed identification of perinatal mortality 20,21,[27][28][29]31,32,34 and three studies had insufficient details to differentiate early pregnancy loss from fetal death at >22 weeks. 30,33,35 No studies reported the incidence of infective endocarditis or neonatal admissions to the intensive care unit.…”

“…21 Of the remaining studies without control groups, one study 32 was awarded the maximum six stars, seven were awarded five stars [27][28][29]31,[33][34][35] and one was awarded three stars. 30 All included studies were assessed as including an adequate representation of cases, with appropriate follow up (Table 1).…”

VTE, Thrombophilia, Antithrombotic Therapy, and Pregnancy

“…49,50,[332][333][334][335][336][337][338][339][340] In a systematic review of observational studies between 1966 and 1997 that reported on outcomes with various anticoagulant regimens in pregnant women with mechanical prosthetic valves, the regimen associated with the lowest risk of valve thrombosis/systemic embolism was the use of vitamin K antagonists throughout pregnancy (3.9%). 49 The use of UFH in the fi rst trimester and near term was associated with a higher risk of valve thrombosis (9.2%).…”

“…49,50,[332][333][334][335][336] The number of pregnancy losses appears higher in those patients who receive either vitamin K antagonists or a heparin throughout pregnancy than in those in whom UFH or LMWH are substituted for vitamin K antagonists in the fi rst trimester and at term. 49,50,[332][333][334][335][336][337][338][339][340] Adjusted-dose bid LMWH throughout pregnancy, with doses adjusted to achieve the manufacturer's peak anti-Xa LMWH 4 h postsubcutaneous injection (Grade 1A). Adjusted-dose UFH throughout pregnancy administered subcutaneously every 12 h in doses adjusted to keep the midinterval aPTT at least twice control or attain an anti-Xa heparin level of 0.35-0.70 units/mL (Grade 1A).…”