High-Versus Low-Dose Warfarin-Related Teratogenicity: A Case Report and Systematic Review

Combination anticoagulation strategy in pregnancy with mechanical valves: The KYBELE study

BACKGROUND

Optimal first-trimester anticoagulation is still challenging in pregnant women with mechanical heart valves (MHVs) requiring high-dose warfarin. This multicenter prospective study aims to determine the optimal anticoagulation regimens for pregnant patients with MHVs.

METHODS

All women were allocated to one of three treatment options during first trimester including lone low-molecular-weight heparin (LMWH), combination of LMWH + 2.5 mg warfarin, and LMWH+4 mg warfarin. Primary maternal outcome included a combination of death, thromboembolism, severe bleeding, and need for treatment of mechanical valve thrombosis (MVT). Any fetal loss was determined as primary fetal outcome.

RESULTS

The study included 78 pregnancies in 65 women with MHVs. Primary maternal outcome rate was 44%, 12.5%, 3.5%, respectively. The rates of primary maternal outcome (44 vs 3.5%, P < .001), obstructive MVT (16 vs 0%, P = .04), MVT requiring treatment (28 vs 0%, P = .003), and cerebral embolism (24 vs 3.4%, P = .041) were found to be significantly higher in lone LMWH group compared to LMWH + 4 mg warfarin group. Moreover, the rates of primary maternal outcome (12.5 vs 44%, P = .015) and treatment for MHV thrombus (4.2 vs 28%, P = .049) were significantly lower in LMWH + 2.5 mg warfarin group compared to lone LMWH group. The incidences of fetal loss were 8 (32%) in the lone LMWH group, 8 (33.3%) in LMWH + 2.5 mg warfarin group, and 11 (37.9%) in LMWH + 4 mg warfarin group (P = .890 for 3-group).Warfarin related-embryopathy was not observed in any case.

CONCLUSIONS

The combined anticoagulation strategy of LMWH plus low-dose warfarin during the first trimester of pregnancy may result in less maternal complications with comparable fetal outcomes in patients with MHVs.

CONDENSED ABSTRACT

Low-molecular-weight heparin (LMWH) is thought to be safer for the fetus, however it is suspected to be less protective for the mother. To solve this dilemma, the authors suggested a novel anticoagulation strategy in pregnant women with prosthetic valves. Seventy-eight pregnancies of 65 women (median age 32 [27-35] years) were included in the study. A combination of LMWH and a reduced dose warfarin were associated with low rates of thrombus-related complications in pregnant patients with mechanical heart valves.

Outcomes in Pregnant Women with Valvular Heart Disease from Portuguese-Speaking African Countries Treated in Portugal through an International Agreement of Health Cooperation

Aims

We performed a clinical audit of maternal and fetal outcomes in pregnant women with valvular heart disease (VHD) from Portuguese-speaking African countries who were transferred for their care, during a twenty-year period, through a memorandum of agreement of international cooperation.

Methods and results

A retrospective analysis of 81 pregnancies in 45 patients with VHD (median age 24, interquartile range 22-29 years) from 2000 to 2020 was performed. The main outcome measures were maternal cardiovascular and fetal outcomes. History of rheumatic heart disease was present in 60 (74.1%) pregnancies. Most were in New York Heart Association (NYHA) functional class I or II; at the first evaluation, 35 (43.2%) were on cardiac medication and 49 (60.5%) were anticoagulated. Forty-eight pregnancies had at least one valvular prosthesis, including 38 mechanical heart valves. During pregnancy, deterioration in NYHA functional class occurred in 35 (42.0%), and eight (9.9%) patients required initiation or intensified cardiac medication. Mechanical valve thrombosis complicated four (4.9%) pregnancies, all cases on heparin, and resulted in one maternal death. Haemorrhagic complications happened in 7 (8.6%) anticoagulated patients, in the immediate postpartum or puerperal period. The 81 pregnancies resulted in 56 (69.1%) live births, while miscarriage and fetal malformations occurred in 19 (23.5%) and 12 (14.8%) pregnancies, respectively. In multivariate analysis, vitamin K antagonist therapy was the only independent predictor of an unsuccessful pregnancy (p = 0.048).

Conclusion

In a high-income country, successful pregnancy was possible with low rate of maternal events in women with VHD transferred from five low-middle income countries in Africa. The use of anticoagulation with a vitamin K antagonist was associated with an unsuccessful pregnancy.

Alternatives to Low Molecular Weight Heparin for Anticoagulation in Pregnant Women with Mechanical Heart Valves in Middle-Income Countries: A Cohort Study

Objective

To compare cardiac complications and pregnancy outcomes in women with mechanical heart valves (MHVs) on two different anticoagulation regimens in a middle-income country.

Methods

We conducted a retrospective cohort study comparing outcomes in pregnant women with MHVs that received vitamin K antagonists (VKAs) throughout pregnancy versus sequential anticoagulation (heparins in the first trimester and peripartum period and VKAs for the remainder of pregnancy), at a tertiary centre in South India, from January 2011 to August 2020.

Results

We identified 138 pregnancies in 121 women, of whom 32 received VKAs while 106 were on sequential anticoagulation. There were no differences between groups with regard to maternal deaths [0 vs. 6 (5.7%), p = 0.34], thromboembolic events [2 (6.3%) vs. 15 (14.2%), p = 0.36], haemorrhagic complications [4 (12.5%) vs. 12 (11.3%), p = 0.85], cardiac events [1 (3.1% vs. 17 (16%), p = 0.07], spontaneous miscarriages [5 (15.6%) vs. 13 (12.3%), p = 0.62], stillbirths [0 vs. 5 (5.4%), p = 0.581] or neonatal deaths [2 (8.7%) vs. 1 (1.1%), p = 0.11]. Both cases of warfarin embryopathy received >5 mg warfarin in the first trimester. Thromboembolic events were associated with subtherapeutic doses of heparin in the first and third trimesters and the early postpartum period. Fetal growth restriction and preterm birth complicated 34 (29.3%) and 26 (22.4%) pregnancies respectively.

Conclusion

Pregnancy complications associated with MHVs in middle-income countries may be reduced by multidisciplinary surveillance, avoiding first-trimester warfarin if daily doses >5 mg and ensuring therapeutic levels of heparin during bridging in the first and third trimesters and peripartum period. Administration of low-dose aspirin should be considered as this may prevent placentally-mediated complications of pregnancy.

Highlights

Pregnancy complications associated with MHVs in LMICs may be reduced by multidisciplinary surveillance, avoiding first-trimester warfarin if the daily dose is >5 mg, ensuring therapeutic levels of heparin in the first trimester and peripartum period.Placentally-mediated complications of pregnancy can be prevented by administering low-dose aspirin.Vitamin K antagonists or sequential regimen can be used as suitable alternatives to LMWH for anticoagulation in pregnant women with MHVs.

Comparison of Different Anticoagulation Regimens Regarding Maternal and Fetal Outcomes in Pregnant Patients With Mechanical Prosthetic Heart Valves (from the Multicenter ANATOLIA-PREG Registry)

Mechanical prosthetic heart valves (MPHVs) are highly thrombogenic, and a pregnancy-induced procoagulant status increases the risk of MPHV thrombosis. Despite numerous case reports, 2 major registries and meta-analyses/systematic reviews, optimal anticoagulation therapy during pregnancy remains controversial. The goal of this study was to evaluate different anticoagulation regimens in pregnant patients with MPHVs. The outcomes of anticoagulation regimens were assessed retrospectively in pregnant women (110 women; 155 pregnancies) with MPHVs. The study population was divided into 5 groups according to anticoagulation regimens used; high-dose warfarin (>5 mg/d) throughout pregnancy (group 1), low-dose warfarin (≤5 mg/d) throughout pregnancy (group 2), low molecular weight heparin (LMWH) throughout pregnancy (group 3), first trimester LMWH, 2nd and 3rd trimester warfarin (group 4), first 2 trimester LMWH, and 3rd trimester warfarin (group 5). Of 155 pregnancies, 55 (35%) resulted in fetal loss; whereas 41 (27%) cases with abortion (miscarriage and therapeutic) and 14 (9%) stillbirths occurred. The comparison of the groups showed that the whole abortion rates including therapeutic abortion were significantly higher in Group 1, and lower in groups 3 and 5 (p <0.001). However, miscarriage rates were similar between the groups. A total of 53 pregnancies (34%) suffered from prosthetic valves thrombosis (PVT) during pregnancy or in the postpartum period. Group 2 had significantly lower rates of PVT than the other groups (p <0.001). In conclusion, the current data suggests that there is no optimal therapy, and that all managements have advantages and disadvantages. Low-dose warfarin (≤5 mg/day) regimen with therapeutic international normalized ratio levels may provide effective maternal protection throughout pregnancy with acceptable fetal outcomes.

Anthracycline and Peripartum Cardiomyopathies

Anthracycline-associated cardiomyopathy and peripartum cardiomyopathy are nonischemic cardiomyopathies that often afflict previously healthy young patients; both diseases have been well described since at least the 1970s and both occur in the settings of predictable stressors (ie, cancer treatment and pregnancy). Despite this, the precise mechanisms and the ability to reliably predict who exactly will go on to develop cardiomyopathy and heart failure in the face of anthracycline exposure or childbirth have proven elusive. For both cardiomyopathies, recent advances in basic and molecular sciences have illuminated the complex balance between cardiomyocyte and endothelial homeostasis via 3 broad pathways: reactive oxidative stress, interference in apoptosis/growth/metabolism, and angiogenic imbalance. These advances have already shown potential for specific, disease-altering therapies, and as our mechanistic knowledge continues to evolve, further clinical successes are expected to follow.

Comparison of international societal guidelines for the diagnosis of suspected pulmonary embolism during pregnancy

Pregnancy-associated pulmonary embolism is one of the leading causes of maternal mortality. Diagnosis of pulmonary embolism in pregnancy is challenging, with symptoms of pulmonary embolism mimicking those of pregnancy. Several key components such as clinical prediction tools, risk stratification, laboratory tests, and imaging widely used for diagnosis of pulmonary embolism in the non-pregnant population show limitations for diagnosis in pregnancy. Further, because of the difficulty of studying pregnant patients, high-quality research evaluating the performance of these diagnostic components in pregnancy is scarce. Seven international medical society guidelines present clinical diagnostic pathways for evaluation of pulmonary embolism in pregnancy that show conflicting recommendations on the use of these diagnostic components. This Review assesses all key components of diagnostic clinical pathways recommended by guidelines for evaluation of pulmonary embolism in pregnancy, reviews current evidence, compares the guideline recommendations with respect to each key component, and provides our preferred diagnostic pathway. It provides the guidelines and available data needed for informed decision making to diagnose pulmonary embolism in pregnancy.

Vitamin K antagonist rodenticides display different teratogenic activity

Vitamin K antagonists (VKA) are not recommended during pregnancy because warfarin (a first-generation VKA) is associated with a malformation syndrome "the fetal warfarin syndrome" (FWS). VKA are also used for rodent management worldwide. Recently, the Committee for Risk Assessment responsible for the European chemical legislation for advances on the safe use of chemicals had classed 8 anticoagulant used as rodenticides in the reprotoxic category 1A or 1B. This classification emerges from a read-across prediction of toxicity considering the warfarin malformation syndrome. Herein, our study explores the teratogenicity of warfarin at the human therapeutic dose and that of bromadiolone, a second-generation anticoagulant rodenticide. Using a rat model, our study demonstrates that warfarin used at the therapeutic dose is able to induce teratogenicity, while in the same conditions bromadiolone does not induce any teratogenic effect, challenging the classification of all VKA as reprotoxic molecules.

Pregnant women, prescription, and fetal risk

Since the historical scandal of thalidomide in the 1960s, practitioners and future mothers are fearful of drugs during pregnancy. In-uterine exposure to drugs can induce major malformation of the fetus or even intrauterine fetal death. Prescribing drugs to a pregnant woman requires particular attention, and it is necessary to consider both the maternal needs and the proven and potential fetal risks. In this chapter, we review the mechanisms for medication transfer from mother to fetus, fetal risk according to pregnancy timeline, and the main dangerous drugs during pregnancy. We also focus on three prescription debates, which are relevant for neurodevelopmental disorder, because they each point to a paradigmatic situation-diethylstilbestrol, which shows transgenerational adversary effects; valproate, which impacts neurodevelopment as a whole; and antidepressants for which the adverse impact on neurodevelopment is still controversial given the impact of depression itself. Finally, we consider the implications for practice and toxicologic research to promote risk prevention.