Pregnancy-associated venous thromboembolism (VTE) in combined heterozygous factor V Leiden (FVL) and prothrombin (FII) 20210 A mutation and in heterozygous FII single gene mutation alone

Impact of double heterozygosity for Factor V Leiden and Prothrombin G20210A on the thrombotic phenotype

INTRODUCTION

Because of the rarity of double heterozygosity for Factor V Leiden (FVL) and Prothrombin (FII) G20210A, little is known about the thrombotic phenotype in double heterozygotes.

MATERIAL AND METHODS

In a retrospective cohort study of patients referred for a thrombophilia work-up, we investigated whether double heterozygotes (n = 138) exhibit a more severe thrombotic phenotype compared with single FVL or FIIG20210A heterozygotes, single FVL homozygotes, or wildtype carriers.

RESULTS

The risk of venous thromboembolism (VTE) was higher for female but not male double heterozygotes compared with single heterozygotes (FVL: 2.51, 95%CI 1.55-4.08, FIIG20210A: 1.75, 95%CI 1.14-2.68) and wildtype carriers (HR 2.53, 95%CI 1.58-4.05) but not compared with FVL homozygotes (HR 1.31, 95%CI 0.94-1.83). Female double heterozygotes developed VTE nearly a decade earlier than wildtype carriers and FVL heterozygotes (mean 44.2 vs. 52.6 and 52.2 years), most often in association with oral contraceptives. Spontaneous VTE and arterial thromboembolic events were not more frequent in double heterozygotes compared with the other genotype groups. Deep vein thrombosis (DVT) of the lower limb was the predominant VTE location in double heterozygotes, atypical vein thrombosis was rare. A phenomenon that has been described as the FVL paradox, a higher proportion of isolated DVT than pulmonary embolism, was also found for double heterozygotes.

CONCLUSION

The thrombotic phenotype in double heterozygotes resembles the appearance of the thrombotic phenotype in FVL carriers but the thrombotic risk is aggravated by women-specific risk factors.

Thromboembolische Komplikationen und die Bedeutung der Thrombophilie in der Schwangerschaft

Ziel: Überblick über Pathogenese, Prophylaxe und Therapie thromboembolischer Komplikationen.

Methode: Literaturrecherche in Pubmed.

Ergebnisse und Diskussion: In der Schwangerschaft verändert sich die plasmatische Gerinnung zugunsten der prokoagulatorischen Eigenschaften des Blutes, um dem Blutverlust bei der Geburt entgegenzuwirken. Venöse Thromboembolien (VTE) gehören in der westlichen Welt weiterhin zu den führenden Ursachen für schwerwiegende mütterliche Morbidität und Sterblichkeit. Das Risiko, eine venöse Thromboembolie zu erleiden, steigt in der Schwangerschaft um das 4-5-fache und in der Postpartum-Periode sogar um das 20-fache. Insbesondere bei Patientinnen mit einer erworbenen oder hereditären Thrombophilie kann es zu vaskulär bedingten Schwangerschaftskomplikationen kommen. Hierzu zählen die tiefe Beinvenenthrombose, die Lungenembolie, aber auch rezidivierende Aborte bei AntiphospholipidSyndrom. Empfehlungen im Hinblick auf die Notwendigkeit einer prophylaktischen Gabe von niedermolekularem Heparin werden bei den verschiedenen Thrombophilien individuell getroffen. Sie sind abhängig von der Art der Thrombophilie, der Eigen- und Familienanamnese hinsichtlich tiefer Beinvenenthrombosen, Lungenembolien oder rezidivierender Aborte sowie dem Verlauf der Schwangerschaft. Eine generelle Empfehlung für eine prophylaktische Heparinisierung bei laborchemisch nachgewiesener Thrombophilie gibt es nicht.

Als antikoagulatorische Therapie der Wahl bei thromboembolischen Komplikationen in der Schwangerschaft gelten die niedermolekularen Heparine, da sie nebenwirkungsarm und nicht teratogen sind. Die Therapie der akuten VTE sollte in der Regel bis 6 Wochen post part-um bei einer Gesamtdauer von mindestens 3 Monaten durchgeführt werden. Liegt ein Anti-phospholipid-Syndrom vor, wird zusätzlich Acetylsalicylsäure (75–100 mg/Tag) empfohlen. Da ein Großteil der tiefen Beinvenenthrombosen in der Schwangerschaft proximal auftreten, ist das Risiko eines postthrombotischen Syndroms hoch. Zur Minimierung von Früh- und Spätkomplikationen bei Thromboembolien in der Schwangerschaft ist eine frühzeitige Diagnostik sowie eine risikoadaptierte Prophylaxe entscheidend.

Risk of venous thrombosis in pregnancy among carriers of the factor V Leiden and the prothrombin gene G20210A polymorphisms

BACKGROUND

Pregnancy is associated with a 10-fold increased risk of venous thrombosis (VT), with different risk profiles for the antenatal and postnatal periods. The purpose of this study was to assess the risk of pregnancy-related VT associated with the factor (F)V Leiden and prothrombin gene G20210A polymorphisms.

MATERIALS AND METHODS

The study comprised 377,155 women with 613,232 pregnancies at 18 Norwegian hospitals from 1 January 1990 to 31 December 2003. Of a total 559 cases with a validated first lifetime diagnosis of VT in pregnancy or within 14 weeks postpartum, and 1229 controls naive for VT, 313 cases and 353 controls donated biological material.

RESULTS

The odds ratios for VT during pregnancy or puerperium were 5.0 [95% confidence interval (CI) 3.1-8.3] and 9.4 (95% CI 2.1-42.4) for heterozygous carriers of the FV Leiden and the prothrombin gene polymorphisms, respectively. All homozygous carriers of the FV Leiden polymorphism (n = 8) and the prothrombin polymorphism (n = 1) developed VT, indicating a very high risk of VT. We estimated that pregnancy-related VT occurred in 1.1/1000 non-carriers, in 5.4/1000 heterozygous carriers of the FV Leiden polymorphism, and in 9.4/1000 heterozygous carriers of the prothrombin polymorphism. To avoid one VT, the number of pregnant women needed to be screened for these two polymorphisms and the number needed to be given thromboprophylaxis were 2015 and 157, respectively.

CONCLUSIONS

Although the relative risk for VT during pregnancy and after delivery was increased among carriers of the FV Leiden and the prothrombin polymorphisms, the overall probability for pregnancy-related VT was low.

Venous thromboembolism in pregnancy

Low molecular weight heparins (LMWHs) appear to be as safe and effective as unfractionated heparin (UFH) for venous thromboembolic disease (VTED) treatment or prophylaxis during pregnancy. Experience with other parenteral anticoagulant drugs is very limited, and no alternative oral anticoagulants are available to date. In addition to cost, challenges of long-term LMWH use during pregnancy that have not been addressed by controlled clinical trials include a) ideal dosing as pregnancy advances, b) the need for LMWH monitoring by anti-Xa activity levels, and c) ideal therapeutic management as the delivery date nears. Because therapeutic-intensity anticoagulation during pregnancy is challenging, many practitioners favor a more "aggressive" approach toward VTED prophylaxis in women perceived to be at very high risk of thrombosis during pregnancy. Best evidence to date suggests that most women with thrombophilias or with a previous "situational" VTED event probably do not require VTED prophylaxis antepartum, but postpartum anticoagulation prophylaxis is recommended for a few weeks. For those with a history of previous idiopathic VTED or VTED associated with "hormonal challenge" (such as with contraceptive use or previous pregnancy), prophylaxis beginning antepartum may be considered and discussed with the patient. Selected cases of "severe" thrombophilia are probably best managed by initiation of pharmacologic VTED prophylaxis antepartum. However, it must be emphasized that data from prospective controlled clinical trials are lacking.

The risk of first venous thromboembolism during pregnancy and puerperium in double heterozygotes for factor V Leiden and prothrombin G20210A

BACKGROUND

The risk of venous thromboembolism (VTE) during pregnancy in double heterozygous carriers of factor (F) V Leiden and prothrombin G20210A is not established. Hence, whether or not these women deserve antithrombotic prophylaxis when pregnant is unknown.

PATIENTS AND METHODS

In the frame of a multicenter family study, 52 double heterozygous carriers of FV Leiden and prothrombin G20210A who had remained pregnant at least once before knowledge of thrombophilia, were retrospectively investigated with respect to the occurrence of first VTE during pregnancy and puerperium. They were compared with 104 heterozygous carriers of FV Leiden, 104 of prothrombin G20210A and 104 women without thrombophilia.

RESULTS

Double heterozygotes were similar to single heterozygous carriers and non-carriers for the age at first pregnancy, age at testing and rate of full-term pregnancies. No VTE during pregnancy was observed in the four groups of women, whereas in the puerperium it occurred in two double carriers (1.8% of pregnancies, 95% CI: 0.5-6.3), three single FV Leiden carriers (1.5%, 0.5-4.3), two single prothrombin G20210A carriers (1%, 0.2-3.6) and one non-carrier (0.4%, 0-2.5).

CONCLUSIONS

The risk of first VTE during pregnancy and puerperium in double heterozygous carriers of FV Leiden and prothrombin G20210A is low and similar to that of single carriers. As for single heterozygotes, antithrombotic prophylaxis in asymptomatic double heterozygous carriers appears to be justified only in puerperium.

Activated Protein C Resistance and Factor V Leiden in Mexico

A common cause of hereditary thrombophilia is activated protein C resistance (APCR), and most cases result from factor V Leiden mutation. An APCR phenotype without association with factor V Leiden has been described. This transversal, observational, nonrandomized study evaluated these 2 phenomena in healthy indigenous and mestizo Mexican subjects (n = 4345), including 600 Mexican natives. No indigenous subjects had APCR, but 82 mestizo subjects did. After retesting, 50 subjects had a negative test. The remaining 32 subjects had factor V Leiden, giving a 0.85% prevalence of factor V Leiden in the mestizo Mexican population. Only 31% of APCR carriers had factor V Leiden. These results show a very low prevalence of APCR and factor V Leiden in Mexico. Except for factor V Leiden, there are no other mutations in the factor V gene responsible for the APCR phenotype. Acquired APCR is nearly twice as prevalent as the inherited variant.

Hypercoagulable State

BACKGROUND

The hypercoagulable state results from a complex interplay of blood coagulation factors, coagulation-inhibitory factors, platelets and the vascular endothelium. Imbalance of the complex interplay between these factors results in thrombosis often complicated by embolism. The causes of thrombosis are varied and maybe congenital or acquired. The current interest is centered on the congenital deficiency of coagulation inhibitors as there is an increasing awareness of their involvement in thrombosis, especially in the young.

METHODS

A total of 42 patients with thrombosis were studied. The most common clinical presentation was deep vein thrombosis. All the cases were evaluated for coagulation inhibitors Antithrombin, resistance to activated protein C, Protein C and Protein S using standard assay kits.

RESULTS

Resistance to activated protein C (n=10) was seen to be the commonest cause of thrombophilia. This was followed by deficiency of Antithrombin (n-4), Protein C (n=3) and Protein S (n=2). Majority of our cases were in the third decade of life.

CONCLUSION

The identification of the underlying aetiology is important for instituting specific therapy and patient management.

Management of pregnant women with increased risk of venous thrombosis

OBJECTIVE

To evaluate the usefulness of score based management of pregnancies with high risk of venous thromboembolism (VTE).

METHOD

116 consecutive pregnancies in 109 women with confirmed thrombophilia and/or history of VTE were studied. Patients were managed in accordance with international recommendations. Recently, a VTE risk prediction score was established. An independent group assessed retrospectively and in a blinded way the usefulness of this score.

RESULTS

Of the 116 pregnancies, an antithrombotic prophylaxis by low molecular weight heparin was prescribed in 61 cases (52.6%). All patients with a positive score (n=57, 49.1%) have been treated with an antenatal thromboprophylaxis. In the population where the score was negative (n=55 cases), none of the patients received antenatal prophylaxis. But, despite a negative score, four patients were treated by their general practitioner. During the study period, there was only one episode of VTE.

CONCLUSION

Implementing this scoring system has resulted in favorable outcomes and a low risk of recurrent thrombosis in this limited series of women with increased risk of VTE.

[Use of antithrombotic agents in pregnant women]

Recommendations of the American College of Chest Physicians (ACCP) concerning antithrombotic treatments were published in September 2004 and discussed in a meeting organized in Paris in November 2004 by a group of experts including a group of authors of the recommendations and French doctors specialized in these subjects. We report here the recommendations concerning pregnancy: French translation of the levels of evidence, of the different schemes for administration of anticoagulants and the text of recommendations concerning the prevention and treatment of venous thrombo-embolism during pregnancy and post-partum. In addition, we have included comments from the French working group.

Pregnancy-associated venous thromboembolism in combined heterozygous factor V Leiden and prothrombin G20210A mutations

CONTEXT

Pregnancy and puerperium raise the risk of thromboembolic events, and these risks are increased in women who are carriers of thrombophilia factors. Prothrombin (FII) G20210A and factor V Leiden heterozygous mutations are associated with moderate risk of thrombosis. The association of these thrombophilic conditions is very rare in pregnancy, and the real risk of thrombosis is unknown.

CASE REPORT

We describe a case of a pregnant woman who was found to be carrier of heterozygous factor V Leiden and prothrombin (FII) G20210A mutations. Five years before pregnancy she had had an episode of extensive deep venous thrombosis in the ileofemoral region, while using hormonal contraceptives. Anticardiolipin antibody (ACA), lupus anticoagulant and deficiencies of protein C, protein S and antithrombin III were evaluated by means of enzyme-linked immunosorbent assay (ELISA), dilute Russell Viper Venom time (dRVVT), coagulometric and chromogenic methods. Deoxyribonucleic acid (DNA) was amplified using the polymerase chain reaction (PCR) to study the factor V Leiden and G20210A mutations in the prothrombin gene and C677T mutation in the methylene tetrahydrofolate reductase (MTHFR) gene. In the sixth week of her first pregnancy, she developed another episode of deep venous thrombosis in the femoropopliteal veins of the right leg. She was treated with low-molecular weight heparin (nadroparin) until parturition (0.3 ml or 2,850 UI/day). The pregnancy evolved without any significant obstetric morbidity. The patient delivered a healthy baby by cesarean section. During the puerperium, she used prophylactic doses of nadroparin for (0.3 ml or 2,850 UI/day) six weeks and had no complications. We suggest that women who have an association of thrombophilia factors and a prior episode of venous thromboembolism must have antepartum anticoagulation management using unfractioned or low-molecular weight heparin and postpartum management using low-molecular weight heparin or oral anticoagulants. Anticoagulation is recommended during pregnancy because the real magnitude of the risk of major and life-threatening thromboembolic events in these women is unknown.

Thromboembolism in pregnancy

PURPOSE OF REVIEW

Venous thromboembolism is the leading cause of maternal death in the UK. Thrombophilia underlies many thrombotic disorders in pregnancy. The high prevalence of thrombophilic defects in the population, the association of defects with venous thromboembolism and the special considerations for management make it a widely debated subject.

RECENT FINDINGS

A limited number of studies measuring the risk of venous thromboembolism in pregnancy with thrombophilia have been conducted within the last year. Studies confirm that heritable thrombophilias are associated with increased risk of venous thromboembolism in pregnancy. However, estimated risks vary between individual studies. The risk of venous thromboembolism with acquired thrombophilia remains unclear. Guidelines have been published to guide clinicians in preventing and treating venous thromboembolism in pregnancy; however, large-scale, randomized controlled trials need to be conducted to establish the effectiveness of administering antithrombotic agents in pregnancy. Although selective thrombophilia screening based on prior history of venous thromboembolism has been proposed, the overall clinical and economic benefit of universal and selective screening is unsupported.

SUMMARY

Due to the lack of studies, gaps still exist in our knowledge of the risk of pregnancy-related venous thromboembolism associated with thrombophilia. In particular, accurate estimates are required for the risks of acquired thrombophilias. Furthermore, the true effectiveness of anticolagulants in pregnancy needs to be established through well-conducted studies and randomized controlled trials. These studies will inform clinicians and help to determine the optimum management and prevention strategies for thrombophilia and venous thromboembolism in pregnancy.

Thrombophilia and adverse pregnancy outcome

PURPOSE OF REVIEW

Recent case-control studies and metaanalyses have attempted to quantify the risks associated with individual thrombophilic defects and adverse clinical events in pregnancy, including fetal loss, preeclampsia, placental abruption and intrauterine growth restriction. This review has examined the evidence.

RECENT FINDINGS

The literature is in general agreement that thrombophilia increases the risk of venous thromboembolism and adverse pregnancy outcomes, including pregnancy loss, preeclampsia, placental abruption and intrauterine growth restriction in pregnancy. However, the size of the estimated risks varies between individual studies due to heterogeneity in study design. Low-molecular-weight heparin has been shown to be the superior choice, on the grounds of safety and effectiveness, in preventing venous thromboembolism and improving pregnancy loss. Large-scale, randomized controlled studies are required, however, to confirm these findings. Although selective thrombophilia screening based on prior venous thromboembolism history has been shown to be marginally more cost-effective than universal screening in pregnancy, the overall clinical and economic benefit of universal and selective screening is unsupported.

SUMMARY

Despite the growing evidence in the literature, there are still gaps in our knowledge of thrombophilia and pregnancy. In particular, accurate estimates are required of the risks of venous thromboembolism and adverse pregnancy outcomes associated with some thrombophilias and the relative clinical and cost-effectiveness of different anticoagulation therapies in the prevention of venous thromboembolism and pregnancy loss. More large-scale studies are required to better inform clinicians and help determine optimum management and prevention strategies of thrombophilia and associated adverse clinical events in pregnancy.

Genetic thrombophilia has pleiotropic effects in pregnancy

Genetic thrombophilia has been established as a risk factor for pregnancy-associated disorders, such as thrombosis, early and late miscarriage, and pre-eclampsia. Associations between the factor V (F5) Leiden G1691A and the prothrombin/factor II (F2) G20210A SNPs and pre-eclampsia have been evaluated in over 50 association studies. A pooled analysis of 23 and 11 studies demonstrates that carriage of the F5 Leiden G1691A (p < 0.001; odds ratio [OR] 2.0; 95% confidence interval [CI] 1.6-2.5) and the F2 G20210A (p < 0.001; OR 1.8; 95% CI 1.1-2.9) SNPs is significantly associated with pre-eclampsia. Besides pre-eclampsia, genotyping for the F5 Leiden G1691A and the F2 G20210A SNPs is also useful for individual risk assessment regarding pregnancy-associated thrombosis. Carriers of the F5 Leiden G1691A SNP will develop this condition in 6.4% of heterozygotes and in 8.9-16.7% of homozygotes. A total of 6.2% of women with the F2 G20210A SNP and 17.8% of women with simultaneous carriage of the F5 Leiden G1691A and F2 G20210A SNPs will develop pregnancy-associated thrombosis. Both the F5 Leiden G1691A and F2 G20210A SNPs are also risk factors of early recurrent, late recurrent and late spontaneous miscarriage based on a published meta-analysis of 31 studies. These women may benefit from prophylactic heparinization. Six case-control and cohort studies of 687 women with genetic thrombophilia document live birth rates of 82% (181/221) using low-molecular-weight heparin or fractionated heparin compared with 20% (95/466) without therapy (p < 0.001, OR 17.7; 95% CI 12.2-25.5). Based on the data in the literature, including association studies and meta-analyses of these association studies, it can be concluded that genetic thrombophilia due to carriage of the F5 Leiden G1691A and F2 G20210A SNPs is a significant and clinically relevant risk factor for pre-eclampsia, pregnancy-associated thrombosis, and early and late miscarriages.

Hormones and pregnancy: thromboembolic risks for women

During their lifetimes, women face several unique situations with an increased risk of venous thromboembolism (VTE). Doctors in a variety of specialties must advise women on the risks of oral contraceptives (OC), hormone replacement or pregnancy. Modern 'low dose' OC are associated with a three to sixfold increased relative risk of VTE. Hormone replacement and selective oestrogen receptor modulators confer a similar two to fourfold increase in thrombotic risk. However, because the baseline incidence of thrombosis is higher in older postmenopausal women, the absolute risk is higher than in younger OC users. The risk of venous thrombosis is six to 10-fold higher during pregnancy than in non-pregnant women of similar age. Thrombophilic disorders increase the thrombotic risk of OC, hormone replacement and pregnancy, especially in women with homozygous or combined defects. This review focuses on recent data estimating the thrombotic risk of hormonal therapies and pregnancy in women with and without other thrombotic risk factors.