Anticoagulant choices in pregnant women with mechanical heart valves: Balancing maternal and fetal risks – the difference the dose makes

Pregnancy outcomes in Chinese women with mechanical heart valves receiving warfarin treatment throughout pregnancy: 14-year experience

OBJECTIVE

The purpose was to evaluate pregnancy outcomes and risk factors associated with fetal complications in Chinese pregnant women with mechanical heart valves (MHVs) taking low-dose warfarin, aiming to fill in the research gap of this area.

METHODS

Between June 2010 and Aug 2023, 122 patients with MHVs who had 151 pregnancies and received warfarin throughout pregnancy were included. We compared them with 302 paired pregnancies without warfarin treatment. Binary logistic regression analyses were performed to explore risk predictors of fetal complications.

RESULTS

Pregnancy loss rate was 37.1 % in women taking warfarin, compared to only 4.6 % for those without warfarin exposure in pregnancy (RR = 8.00, 95 % CI: 4.61-13.90). In pregnant women with MHVs, there were 34 spontaneous abortions, 22 stillbirths and 1 neonatal malformation. In the first, second and third pregnant trimesters of women with MHVs, fetal complication incidences were 19.2 %, 9.9 % and 8.0 %, respectively. 86.0 % of fetal complications occurred in women taking a warfarin dose ≤5 mg/d, accounting for 94.0 % of the total population. The newborns' birth weight, gestational age and 1-minute Apgar score were significantly lower in pregnancies treated with warfarin compared to those without warfarin exposure. Only 2.0 % of postpartum hemorrhage and no thrombosis or maternal mortality data were collected in pregnant women on warfarin in this study.

CONCLUSION

Most Chinese pregnant women take a warfarin daily dose ≤5 mg and they might have only around 60 % chance of giving birth to a live baby without maternal complications.

A 'dreaded' complication of stuck prosthetic valve in the first trimester pregnancy

A dramatic rise in cardiac output with a decrease in afterload are the hallmark of hemodynamic variations induced by normal pregnancy, which requires significant cardiac adaptation. Females with rheumatic mitral valve disease who have had a mitral valve replacement in the past are increasingly choosing to become pregnant. Hypercoagulability of pregnancy, problems with anticoagulant therapy along with hemodynamic changes in pregnancy increase the risk of cardiac complications in this subset. There is a paucity of research on the management of problems in patients with cardiac prosthetic valves. We present a case of primigravida with a history of mitral valve replacement, presenting with a stuck valve.

Learning objectives

•Pregnancy is a pro-thrombotic state•Pregnancy with a mechanical heart valve has high risk of stuck vale despite adequate anti-coagulation•Management of such high-risk cases must be carried out at a tertiary care center with all facilities•Multi-disciplinary approach is required to deal with pregnant women with mechanical heart valve.

A Study of Fertility and Pregnancy Outcomes in Women after Surgery for Valvular Heart Disease

Objectives:

Chronic Rheumatic Heart Disease (CRHD)is a common condition in India. CRHD accounts for a majority of heart valve surgery, including those in the younger age group. These young women almost traditionally get married in a country like India, and the social pressure to bear children is tremendous. Anticoagulation and the postoperative state of the patient itself can be a risk factor for maternal and fetal outcomes. There is very little data available for the same in India.

Materials and Methods:

In this study, 100 cases were studied retrospectively to study the fertility patterns after valvular heart surgery including fetal outcomes. This study was conducted at Nizam’s Institute of Medical Sciences, Hyderabad in which pregnancy, anticoagulation, maternal and fetal outcomes were studied.

Results:

A total of 63 patients conceived after surgery (pregnancy rate = 63%/ failure rate =37%) (p=0.001). Fetal loss occurred in 6 of the pregnancies, due to spontaneous abortion (n=3) and medical abortion (n=3). Parity, associated conditions and age did not affect the outcome. During pregnancy, 28 patients switched to UF heparin, 31 stayed on warfarin, 4 did not take any anticoagulation. Fetal loss was observed in 3 patients on Warfarin during pregnancy and 3 on UF heparin. Maternal loss was observed in 4 patients out of which 2 were on Warfarin, 1 on unfractionated UF heparin and 1 did not take any anticoagulation during pregnancy. In comparison, warfarin and UF heparin had similar fetal outcomes.

Conclusion:

The study recorded good outcomes irrespective of type of prosthesis and anticoagulation.

Managing anticoagulation in pregnancy for the anaesthetist on the labour ward

Pregnancy is a hypercoaguable state. As part of the multidisciplinary team on labour ward, the anaesthetist plays a role particularly in advising the women and the obstetric team regarding the timing and even choice of regional analgesia given the potential risk of complications, as this may be affected by the anticoagulation treatment pregnant women may be on. It is important to understand the type of anticoagulation regimens parturients might be on and what sort of risk assessment they must undergo, as this has obstetric and anaesthetic implications. Although a rare presentation, management of women with mechanical prosthetic heart valves who are pregnant requires detailed and highly specialised care in tertiary care centres with a well-developed multidisciplinary team and pathway. Despite their rare presentation, it is important to understand the intricate and complex management that these women require as they have a high morbidity and mortality rate.

Clinical management of coagulation status and placenta previa in a pregnant woman with Marfan's syndrome after mitral and aortic mechanical heart valve replacement

Pregnancy with a mechanical heart valve (MHV) is high risk for valve thrombosis because pregnancy is a hyper-coagulation state. In addition, warfarin use during pregnancy is restricted due to its fetotoxicity, and postpartum bleeding may be increased with anticoagulation. In particular, placenta previa under anticoagulation may cause massive postpartum bleeding. The optimal anticoagulation for a pregnant woman with mitral and aortic double MHVs is not known. In addition, suitable techniques for control of bleeding in a case of placenta previa under anticoagulation are not known. Thus, a case of a pregnant woman with mitral and aortic double MHVs and placenta previa is presented. The case was managed without valve thrombosis through precise unfractionated heparin dose adjustment and frequent activated partial thromboplastin time monitoring, along with maintenance of antithrombin levels. Compression sutures were found to be effective for controlling bleeding from the attachment site of placenta previa even under anticoagulation.

Cardiac arrhythmias in pregnant women: need for mother and offspring protection

Cardiac arrhythmias are the most common cardiac complication reported in pregnant women with and without structural heart disease (SHD); they are more frequent among women with SHD, such as cardiomyopathy and congenital heart disease (CHD). While older studies had indicated supraventricular tachycardia as the most common tachyarrhythmia in pregnancy, more recent data indicate an increase in the frequency of arrhythmias, with atrial fibrillation (AF) emerging as the most frequent arrhythmia in pregnancy, attributed to an increase in maternal age, cardiovascular risk factors and CHD in pregnancy. Importantly, the presence of any tachyarrhythmia during pregnancy may be associated with adverse maternal and fetal outcomes, including death. Thus, both the mother and the offspring need to be protected from such consequences. The use of antiarrhythmic drugs (AADs) depends on clinical presentation and on the presence of underlying SHD, which requires caution as it promotes pro-arrhythmia. In hemodynamically compromised women, electrical cardioversion is successful and safe to both mother and fetus. Use of beta-blockers appears quite safe; however, caution is advised when using other AADs, while no AAD should be used, if at all possible, during the first trimester when organogenesis takes place. Regarding the anticoagulation regimen in patients with AF, warfarin should be substituted with heparin during the first trimester, while direct oral anticoagulants are not indicated given the lack of data in pregnancy. Finally, for refractory arrhythmias, ablation and/or device implantation can be performed with current techniques in pregnant women, when needed, using minimal exposure to radiation. All these issues and relevant current guidelines are herein reviewed.

Mechanical heart valves and pregnancy: Issues surrounding anticoagulation. Experience from two obstetric cardiac centres

Background

Pregnant women with mechanical heart valves are at significant risk of obstetric/cardiac complications. This study compares the anticoagulation management in two obstetric cardiac centres.

Methods

Retrospective case-note review from Chelsea and Westminster/Royal Brompton Hospitals (CR) and Erasmus Medical Centre (EMC). Main outcome measure was mechanical heart valve thrombosis.

Results

Nineteen pregnancies from CR and 25 pregnancies from EMC were included. Most women were on low-molecular-weight heparin (LMWH) throughout pregnancy at CR, whereas at EMC most had LMWH in the first trimester and vitamin K antagonists in subsequent trimesters. Peak anti-factor Xa were performed monthly at CR, levels 0.39-1.51 IU/mL (mean 0.82 IU/mL). Anticoagulation management peri-partum was inconsistent. Delivery was mainly by caesarean section at CR (74%) and vaginal delivery at EMC (64%). No maternal deaths and only one mechanical heart valve thrombosis at CR. Two mechanical heart valve thromboses and one maternal death at EMC.

Conclusion

Peri-partum anticoagulation strategies, anticoagulation monitoring and mode of delivery inconsistencies reported.

Low-dose warfarin maternal anticoagulation and fetal warfarin syndrome

Fetuses exposed to warfarin during pregnancy are at an increased risk of developing an embryopathy known as fetal warfarin syndrome or warfarin embryopathy. The most consistent anomalies are nasal hypoplasia and stippling of vertebrae or bony epiphyses. Management of pregnant patients on anticoagulation is challenging. Current guidelines suggest the use of warfarin if the therapeutic dose is ≤5 mg/day. We report the case of a newborn with signs of warfarin embryopathy born from a mother anticoagulated with warfarin due to mechanical mitral and aortic heart valves. Warfarin was required at the dose of 5 mg/day and was withheld without medical advice between weeks 8 and 10 with no other anticoagulation. The newborn presented with skeletal abnormalities and a ventricular septal defect that have not required specific treatment during the first year of life. Low-dose warfarin is associated with a lower risk of warfarin-related fetopathy but the risk of embryopathy seems unchanged.

Atrial fibrillation in pregnancy: a growing challenge

BACKGROUND

Atrial fibrillation (AF) constitutes a relatively infrequent pregnancy complication, which may be a therapeutic Gordian knot. Indeed, sparse data exist regarding the prevalence, prognosis, and management of AF during pregnancy. In general, AF occurs as a benign, self-limited arrhythmia, but occasionally may have severe hemodynamic consequences in pregnant patients suffering from heart failure, congenital heart disease, or other comorbidities. Extra-cardiac causes of AF should always be meticulously excluded.

REVIEW

Treatment decisions are difficult, since medications may cross the placental barrier and potentially affect fetal growth and organogenesis, or even result in fetal bradyarrhythmias. Treatment goals are not differentiated in comparison to those regarding AF occurring in the general population. Still, while maternal treatment is prioritized, issues regarding fetal health must deliberately be considered. Consequently, hemodynamic instability is to be promptly treated with synchronized electrical cardioversion. In contrast, in stable patients, pharmacologic cardioversion, under appropriate antithrombotic regimen, should be attempted. Selection of appropriate antithrombotic therapy, including novel oral anticoagulants, imposes further difficulties on therapeutic decision-making. Further clinical trials are warranted in order to assess the pathophysiology and prognosis of AF in pregnancy and ameliorate the evidence-based therapeutic strategy in this specific group of the population.

Pregnancy in Women With a Mechanical Heart Valve: Data of the European Society of Cardiology Registry of Pregnancy and Cardiac Disease (ROPAC)

BACKGROUND

Pregnant women with a mechanical heart valve (MHV) are at a heightened risk of a thrombotic event, and their absolute need for adequate anticoagulation puts them at considerable risk of bleeding and, with some anticoagulants, fetotoxicity.

METHODS AND RESULTS

Within the prospective, observational, contemporary, worldwide Registry of Pregnancy and Cardiac disease (ROPAC), we describe the pregnancy outcome of 212 patients with an MHV. We compare them with 134 patients with a tissue heart valve and 2620 other patients without a prosthetic valve. Maternal mortality occurred in 1.4% of the patients with an MHV, in 1.5% of patients with a tissue heart valve (P=1.000), and in 0.2% of patients without a prosthetic valve (P=0.025). Mechanical valve thrombosis complicated pregnancy in 10 patients with an MHV (4.7%). In 5 of these patients, the valve thrombosis occurred in the first trimester, and all 5 patients had been switched to some form of heparin. Hemorrhagic events occurred in 23.1% of patients with an MHV, in 5.1% of patients with a tissue heart valve (P<0.001), and in 4.9% of patients without a prosthetic valve (P<0.001). Only 58% of the patients with an MHV had a pregnancy free of serious adverse events compared with 79% of patients with a tissue heart valve (P<0.001) and 78% of patients without a prosthetic valve (P<0.001). Vitamin K antagonist use in the first trimester compared with heparin was associated with a higher rate of miscarriage (28.6% versus 9.2%; P<0.001) and late fetal death (7.1% versus 0.7%; P=0.016).

CONCLUSIONS

Women with an MHV have only a 58% chance of experiencing an uncomplicated pregnancy with a live birth. The markedly increased mortality and morbidity warrant extensive prepregnancy counseling and centralization of care.

Successful fibrinolytic treatment of prosthetic heart valve thrombosis using streptokinase

OBJECTIVES

This study aims to evaluate the clinical outcome of fibrinolytic treatment of prosthetic valve thrombosis (PVT) with 'streptokinase' as a first line treatment for these cases.

METHODS

The study group was 20 consecutive patients (10 females) diagnosed with PVT. The protocol for streptokinase administration was either accelerated (intravenous infusion of 0.5 million IU over 30 minutes followed by 0.15 million IU/h) or conventional (intravenous infusion of 0.25 million IU over 30 minutes followed by 0.15 million IU/h). Success of fibrinolytic therapy was defined as complete restoration of valve function in the presence or absence of complications.

RESULTS

Eighteen patients (90%) had mitral PVT and two (10%) had aortic PVT. Thrombolytic therapy with streptokinase was successful in all but one case, with a total mortality of four cases (20%). In PVT episodes, before streptokinase therapy, the prosthetic valve areas (in all cases, mitral and aortic positions) were 0.82 ± 0.21, 0.83 ± 0.21, and 0.73 ± 0.18 cm²; and the peak and mean transvalvular gradients were 38.7 ± 16.7 and 25.4 ± 8.7, 34.1 ± 8.8 and 23.2 ± 5.4, and 80.0 ± 14.1 and 45.0 ± 7.1 mmHg, respectively. After streptokinase therapy, the prosthetic valve area and peak and mean transvalvular gradients improved significantly (for all cases, mitral and aortic positions: valve area 2.17 ± 0.58, 2.21 ± 0.61, and 1.85 ± 0.07 cm², peak gradient 18.7 ± 11.0, 16.4 ± 7.7, and 39.0 ± 18.4, and mean gradient 9.6 ± 7.1, 8.2 ± 5.3, and 22.0 ± 11.3 mmHg, respectively; paired t-test, P<0.001 for pre- versus post-streptokinase infusion for all variables).

CONCLUSION

Fibrinolytic therapy using streptokinase was an effective therapeutic strategy for the management of PVT and is a reasonable alternative to surgery.

Mechanical Prosthetic Valves and Pregnancy: A therapeutic dilemma of anticoagulation

Choosing the best anticoagulant therapy for a pregnant patient with a mechanical prosthetic valve is controversial and the published international guidelines contain no clear-cut consensus on the best approach. This is due to the fact that there is presently no anticoagulant which can reliably decrease thromboembolic events while avoiding damage to the fetus. Current treatments include either continuing oral warfarin or substituting warfarin for subcutaneous unfractionated heparin or low-molecular-weight heparin (LMWH) in the first trimester (6-12 weeks) or at any point throughout the pregnancy. However, LMWH, while widely-prescribed, requires close monitoring of the blood anti-factor Xa levels. Unfortunately, facilities for such monitoring are not universally available, such as within hospitals in developing countries. This review evaluates the leading international guidelines concerning anticoagulant therapy in pregnant patients with mechanical prosthetic valves as well as proposing a simplified guideline which may be more relevant to hospitals in this region.

Transfer of dabigatran and dabigatran etexilate mesylate across the dually perfused human placenta

OBJECTIVE

To assess the transplacental pharmacokinetics at term of the oral thrombin inhibitor, dabigatran, and its prodrug, dabigatran etexilate mesylate, to estimate fetal drug exposure.

METHODS

Placentae were obtained with informed consent after cesarean delivery of healthy term pregnancies in Toronto, Ontario, Canada. The transplacental transfer of dabigatran and dabigatran etexilate mesylate was separately assessed using the ex vivo dual perfusion of an isolated human placental cotyledon. Dabigatran, at a concentration of 35 ng/mL, was added to the maternal circulation at the start of the experimental phase. Maternal and fetal samples were taken throughout the preexperimental (1 hour) and experimental (3 hours) phases for measurement of dabigatran and markers of placental viability. Separate placenta perfusions with dabigatran etexilate mesylate were conducted at an initial maternal concentration of 3.5 ng/mL. Dabigatran and dabigatran etexilate mesylate were measured using liquid chromatography-tandem mass spectrometry.

RESULTS

There was slower transfer of dabigatran compared with antipyrine from the maternal-to-fetal circulation, because the median fetal-to-maternal concentration ratio was 0.33 (interquartile range 0.29-0.38) after 3 hours (n=3). The prodrug, dabigatran etexilate mesylate, had limited placental transfer as characterized by a fetal-to-maternal ratio of 0.17 (interquartile range 0.15-0.17) after 3 hours (n=3). Placental viability markers for all perfusions were within normal ranges.

CONCLUSION

This report provides direct evidence of the transfer of dabigatran and its prodrug across the term human placenta from the mother to the fetus. From a clinical perspective, these data suggest that, pending further study, dabigatran should not be used for anticoagulation of pregnant women, because the drug may have an adverse effect on fetal blood coagulation.

Thromboembolism in pregnancy: challenges and controversies in the prevention of pregnancy-associated venous thromboembolism and management of anticoagulation in women with mechanical prosthetic heart valves

Thromboembolism in pregnancy is an important clinical issue. Despite identification of maternal and pregnancy-specific risk factors for development of pregnancy-associated venous thromboembolism, limited data are available to inform on optimal approaches for prevention. The relatively low overall prevalence of pregnancy-associated venous thromboembolism has prompted debate about the validity of recommendations, which are mainly based on expert opinion, and have resulted in an increased use of pharmacological thromboprophylaxis in pregnancy and postpartum. A pragmatic approach is required in the absence of more robust data. Anticoagulation management of pregnant women with mechanical prosthetic heart valves is particularly challenging. Continuation of therapeutic anticoagulation during pregnancy is essential to prevent valve thrombosis. Warfarin, the most effective anticoagulant, is associated with adverse fetal outcomes, including embryopathy and stillbirth. Fetal outcome is improved with therapeutic-dose low-molecular-weight heparin, but there may be more thromboembolic complications. More intensive anticoagulation, targeting higher trough anti-Xa levels, may reduce the risk of valve thrombosis.

Management of cardiovascular diseases during pregnancy

The prevalence of cardiovascular diseases (CVDs) in women of childbearing age is rising. The successes in medical and surgical treatment of congenital heart disease have led to an increasing number of women at childbearing age presenting with problems of treated congenital heart disease. Furthermore, in developing countries and in immigrants from these countries, rheumatic valvular heart disease still plays a significant role in young women. Increasing age of pregnant women and increasing prevalence of atherosclerotic risk factors have led to an increase in women with coronary artery disease at pregnancy. Successful management of pregnancy in women with CVDs requires early diagnosis, a thorough risk stratification, and appropriate management by a multidisciplinary team of obstetricians, cardiologists, anesthesiologists, and primary care physicians. The following review is based on the recent European guidelines on the management of CVDs during pregnancy, which aim at providing concise and simple recommendations for these challenging problems.

Neurology of pregnancy

Pregnancy creates alterations in maternal physiology which predispose to unique neurologic disorders. Pre-eclampsia, eclampsia, certain types of ischemic and hemorrhagic stroke, reversible cerebral vasoconstriction syndrome, posterior reversible encephalopathy syndrome, and thunderclap headache all appear to share a common origin from vascular endothelial dysfunction, with overlapping clinical presentations. Multiple sclerosis often improves during pregnancy. Compression mononeuropathies may occur in the extremities. Myasthenia gravis may affect second stage labor. Various inflammatory peripheral neuropathies, dystrophies, myopathies may occur during pregnancy. The safety of specific immune suppressants is reviewed. Epilepsy does not have a significant effect upon the course of pregnancy, albeit there is a modest increase in the need for cesarean section. Certain antiepileptic drugs may produce fetal malformations, most notably valproic acid. Brain tumors are rare during pregnancy, but may increase in size due to activation of hormonal receptors on tumor cells surfaces, water retention, and engorged blood vessels.