Genetic susceptibility to venous thrombosis

Pulmonary Embolism

Venous thromboembolism (VTE) includes pulmonary embolism (PE) and deep vein thrombosis. PE is the third most common cause of cardiovascular death worldwide after stroke and heart attack. Management of PE has evolved recently with the availability of local thrombolysis; mechanical extraction devices; hemodynamic support devices, like extracorporeal membrane oxygenation; and surgical embolectomy. There has been development of multidisciplinary PE response teams nationwide to optimize the care of patients with VTE. This review describes the epidemiology of PE, discusses diagnostic strategies and current and emerging treatments for VTE, and considers post-PE follow-up care.

Review article: a multidisciplinary approach to the diagnosis and management of Budd-Chiari syndrome

BACKGROUND

Budd-Chiari syndrome (BCS) is a rare but fatal disease caused by obstruction in the hepatic venous outflow tract.

AIM

To provide an update of the pathophysiology, aetiology, diagnosis, management and follow-up of BCS.

METHODS

Analysis of recent literature by using Medline, PubMed and EMBASE databases.

RESULTS

Primary BCS is usually caused by thrombosis and is further classified into "classical BCS" type where obstruction occurs within the hepatic vein and "hepatic vena cava BCS" which involves thrombosis of the intra/suprahepatic portion of the inferior vena cava (IVC). BCS patients often have a combination of prothrombotic risk factors. Aetiology and presentation differ between Western and certain Asian countries. Myeloproliferative neoplasms are present in 35%-50% of European patients and are usually associated with the JAK2-V617F mutation. Clinical presentation is diverse and BCS should be excluded in any patient with acute or chronic liver disease. Non-invasive imaging (Doppler ultrasound, computed tomography, or magnetic resonance imaging) usually provides the diagnosis. Liver biopsy should be obtained if small vessel BCS is suspected. Stepwise management strategy includes anticoagulation, treatment of identified prothrombotic risk factors, percutaneous revascularisation and transjugular intrahepatic portosystemic stent shunt to re-establish hepatic venous drainage, and liver transplantation in unresponsive patients. This strategy provides a 5-year survival rate of nearly 90%. Long-term outcome is influenced by any underlying haematological condition and development of hepatocellular carcinoma.

CONCLUSIONS

With the advent of newer treatment strategies and improved understanding of BCS, outcomes in this rare disease have improved over the last three decades. An underlying haematological disorder can be the major determinant of outcome.

Asymmetric independence modeling identifies novel gene-environment interactions

Most genetic or environmental factors work together in determining complex disease risk. Detecting gene-environment interactions may allow us to elucidate novel and targetable molecular mechanisms on how environmental exposures modify genetic effects. Unfortunately, standard logistic regression (LR) assumes a convenient mathematical structure for the null hypothesis that however results in both poor detection power and type 1 error, and is also susceptible to missing factor, imperfect surrogate, and disease heterogeneity confounding effects. Here we describe a new baseline framework, the asymmetric independence model (AIM) in case-control studies, and provide mathematical proofs and simulation studies verifying its validity across a wide range of conditions. We show that AIM mathematically preserves the asymmetric nature of maintaining health versus acquiring a disease, unlike LR, and thus is more powerful and robust to detect synergistic interactions. We present examples from four clinically discrete domains where AIM identified interactions that were previously either inconsistent or recognized with less statistical certainty.

Re-Examining Genetic Screening and Oral Contraceptives: A Patient-Centered Review

The World Health Organization classifies combined hormonal contraception as an unacceptable health risk in the presence of a known thrombogenic mutation but advises against routine thrombophilia screening before initiating combined oral contraceptives (COCs) on the grounds of high screening costs and low prevalence. From the perspective of patient-centered care, we examine cost, prevalence, and other published arguments for and against thrombophilia screening before initiating COCs. Our patient-centered review draws on relevant empirical evidence concerning the advantages and disadvantages of thrombophilia screening, while placing the discussion in the broader context of evolving attitudes toward genetic testing and a shifting policy landscape that provides many women direct access to COCs and/or thrombophilia screening. Given variation in prior probabilities of thrombophilia, expected exposure to other risk factors for venous thromboembolism, attitudes towards risk, expected reactions to a positive test result, ability to pay, and concerns about genetic discrimination, we conclude that the current one-size-fits-most approach is not consistent with patient-centered care. Instead, we advocate for greater patient and provider education concerning the implications of thrombophilia screening. Moreover, we recommend offering patients optional thrombophilia screening before initiating COCs.

Venous thromboembolism prophylaxis using the Caprini score

Venous thromboembolism (VTE) including pulmonary embolism (PE) and deep vein thrombosis (DVT) is one of the leading causes of preventable cardiovascular disease in the United States (US) and is the number one preventable cause of death following a surgical procedure. Post-operative VTE is associated with multiple short and long-term complications. We will focus on reviewing the many faces of VTE in detail as they represent common challenging scenarios in clinical practice.

Venous Thromboembolism Prophylaxis: A Narrative Review With a Focus on the High-Risk Critically Ill Patient

Venous thromboembolism (VTE) is a major health concern associated with significant morbidity and mortality. Critically ill patients are at an increased risk of VTE compared to general medical patients due to unique risk factors: prolonged immobilization, invasive lines and devices, certain medications, and acquired thrombophilia. Furthermore, VTE in the critically ill is associated with increased duration of mechanical ventilation, increased length of intensive care unit and hospital stay, and a trend toward increased mortality. Clinical practice guidelines therefore recommend VTE prophylaxis with either subcutaneous heparin or low-molecular-weight heparin for all critically ill patients without contraindication. Yet, many patients will develop VTE despite appropriate pharmacologic prophylaxis, which has led to interest in risk-stratifying critically ill patients for more aggressive prophylaxis strategies. Recent research identified patients at highest risk of failure of thromboprophylaxis and provided insight into the pathophysiologic mechanisms. Obesity and the receipt of vasopressors are 2 risk factors consistently identified in observational studies; further clinical data support decreased absorption of anticoagulant administered via the subcutaneous route as the likely mechanism behind thromboprophylaxis failure in these patient populations. Several studies have investigated novel thromboprophylaxis strategies to circumvent pharmacokinetic limitations in patients who are obese or on vasopressors: increased fixed-dose, weight-based subcutaneous, or continuous intravenous infusion of a prophylactic dose of anticoagulant has shown promise in limited studies; however, the results have yet to demonstrate superiority compared to current standard-of-care. This review discusses observational studies identifying patients at risk of thromboprophylaxis failure and critiques clinical studies evaluating novel thromboprophylaxis strategies in high-risk, critically ill patients with a focus on their limitations. Future studies are currently being conducted that will provide further guidance into the appropriate use of individualized thromboprophylaxis.

Padua FIXa resistance to Protein S and a potential therapy for hyperactive FIXa

INTRODUCTION

Abnormalities in the levels and functions of proteins that maintain hemostasis can cause thrombosis. Factor IX (FIX) R338L, i.e., Factor IX Padua, is a hyperactive clotting factor that promotes thrombosis. The R338L mutation increases the clotting rate by 8-fold despite increasing the Factor IXa enzymatic activity by only 2-fold. Protein S (PS) is a natural anticoagulant that directly inhibits FIXa. Because individuals affected by the R338L mutation have normal concentrations of PS, we speculated that the Padua hypercoagulation phenotype is due to decreased inhibition of FIXa R338L by PS.

METHODS

We measured the ability of PS to inhibit FIX R338L, and we assessed the ability of PS to mitigate the prothrombotic effect FIX R338L.

RESULTS

Plasma clotting assays demonstrated that 3-fold more PS was required to inhibit FIXa R338L compared with inhibition of wild type FIXa. Thrombin generation assays with Padua patient plasma recapitulated this biochemical consequence of the R338L mutation. Importantly, the less efficient inhibition of FIXa R338L was reversed by increasing PS concentration. Binding and co-immunoprecipitation studies revealed that the decrease in the inhibition of FIXa R338L by PS was caused by a 3- to 4-fold reduction in FIXa R338L affinity for PS.

CONCLUSION

In summary, the resistance of FIXa R338L to inhibition by PS likely contributes to the unexpectedly high clotting rate in Padua individuals. Moreover, PS-mediated reversal of the pathological properties of FIXa R338L suggests that PS administration may be a novel and effective means to mitigate thrombophilia caused by any source of elevated FIXa activity.

A systematic review of cost-effectiveness analysis of screening interventions for assessing the risk of venous thromboembolism in women considering combined oral contraceptives

Use of combined oral contraceptives (COCs) by women increases the risk of venous thromboembolism (VTE), which can have a major impact on an individuals' quality of life. VTE is also associated with an increase in healthcare costs. Our aim was to systematically review cost-effectiveness analyses (CEAs) considering any screening for risk of VTE in women using COCs. The quality of reporting in each study was assessed, a summary of results was prepared, and the key drivers of cost effectiveness in each of the eligible CEAs were identified. A search strategy using MeSH terms was performed in MEDLINE, Embase, the Centre for Review and Dissemination (CRD) database including the Economic Evaluation Database from the UK National Health Service, and Cochrane reviews. Two reviewers independently screened and determined the final articles, and a third reviewer resolved any discrepancies. Consolidated Health Economic Evaluation Reporting Standards was used to assess the quality of reporting in terms of perspective, effectiveness measures, model structure, cost, time-horizon and discounting. Four publications (three from Europe, one from the United States) were eligible for inclusion in the review. According to current criteria, relevant elements were sometimes not captured and the sources of epidemiological and effectiveness data used in the CEAs were of limited quality. The studies varied in terms of type of costs assessed, country settings, model assumptions and uncertainty around input parameters. Key drivers of CEAs were sensitivity and specificity of the test, incidence rate of VTE, relative risk of prophylaxis, and costs of the test. The reviewed studies were too dissimilar to draw a firm conclusion on cost-effectiveness analysis about universal and selective screening in high-risk groups. The new emerging diagnostic tools for identifying women at risk of developing VTE, that are more predictive and less costly, highlight the need for more studies that apply the latest evidence and utilize robust methods for cost-effectiveness analysis. This information is required to improve decision making for this pertinent issue within personalized medicine.

Activated protein C, protease activated receptor 1, and neuroprotection

Protein C is a plasma serine protease zymogen whose active form, activated protein C (APC), exerts potent anticoagulant activity. In addition to its antithrombotic role as a plasma protease, pharmacologic APC is a pleiotropic protease that activates diverse homeostatic cell signaling pathways via multiple receptors on many cells. Engineering of APC by site-directed mutagenesis provided a signaling selective APC mutant with 3 Lys residues replaced by 3 Ala residues, 3K3A-APC, that lacks >90% anticoagulant activity but retains normal cell signaling activities. This 3K3A-APC mutant exerts multiple potent neuroprotective activities, which require the G-protein-coupled receptor, protease activated receptor 1. Potent neuroprotection in murine ischemic stroke models is linked to 3K3A-APC-induced signaling that arises due to APC's cleavage in protease activated receptor 1 at a noncanonical Arg46 site. This cleavage causes biased signaling that provides a major explanation for APC's in vivo mechanism of action for neuroprotective activities. 3K3A-APC appeared to be safe in ischemic stroke patients and reduced bleeding in the brain after tissue plasminogen activator therapy in a recent phase 2 clinical trial. Hence, it merits further clinical testing for its efficacy in ischemic stroke patients. Recent studies using human fetal neural stem and progenitor cells show that 3K3A-APC promotes neurogenesis in vitro as well as in vivo in the murine middle cerebral artery occlusion stroke model. These recent advances should encourage translational research centered on signaling selective APC's for both single-agent therapies and multiagent combination therapies for ischemic stroke and other neuropathologies.

Hypercoagulable States and Thrombophilias: Risks Relating to Recurrent Venous Thromboembolism

Inherited and acquired thrombophilias and hypercoagulable states, such as active cancer, estrogen-induced, autoimmune disorders, major surgery, hospitalization, and trauma, are well-known risk factors for venous thromboembolism (VTE). The effect of these on recurrent VTE is different for each specific risk factor. The major risk factors affecting VTE recurrence include the presence of active cancer and an unprovoked first VTE. In addition, the use of combined female hormones in a woman with a previous history of estrogen-related VTE is a major risk factor for VTE recurrence. The extent of influence of inherited thrombophilia on the risk of recurrence is controversial. Conversely, the presence of antiphospholipid antibodies, specifically triple positive carriers, appears to increase the risk of VTE recurrence. Understanding the rates of recurrent VTE in a patient and the individual risk of bleeding is important in determining the duration of anticoagulation therapy.

High prevalence of factor V Leiden and prothrombin G20101A mutations in Kashmiri patients with venous thromboembolism

AIM

The genetic variants of the factor V (G1691A), prothrombin (G20210A) and MTHFR (C677T) genes have been widely implicated as inherited risk factors for developing venous thrombosis. This study was undertaken to reveal the frequency of these mutations in Kashmiri patients with venous thromboembolism.

METHODOLOGY

A case-control study was designed with 250 VTE patients and 250 healthy controls. The mutations were analysed using ARMS-PCR and PCR-RFLP approach.

RESULT

The factor V Leiden G1691A mutation was found in 17/250 (6.8%) VTE patients and prothrombin G20210A mutation was found in 7/250 (2.8%) VTE patients while no mutation was found in any of the healthy controls. Both the mutations were found to be significantly associated with the increased risk of VTE (p = 0.0001 and 0.0150 respectively) while no association of VTE risk with MTHFR C677T polymorphism was found (p = 0.53).

CONCLUSION

The increased frequency of factor V Leiden G1691A and prothrombin G20210A mutation in VTE patients indicates a significant role of these mutations in the development of VTE in our population. We therefore suggest the routine screening of these two mutations as thrombophilic markers in Kashmiri patients with venous thromboembolism.

Recurrent pulmonary embolism associated with deep venous thrombosis diagnosed as protein s deficiency owing to a novel mutation in PROS1: A case report

RATIONALE

Protein S (PS) deficiency that can be inherited or acquired is an independent risk factor for venous thromboembolism (VTE).

PATIENT CONCERNS

In this report, we present a case of recurrent pulmonary embolism (PE) and deep venous thrombosis (DVT) due to PS deficiency.

DIAGNOSES

A 32-year-old male patient with significant decrease in PS activity was detected by laboratory tests. Genetic examination of the PROS1 gene showed a transition of G to T in exon 14 (c.1792 G>T, p.E598X), which was a paternal inherited heterozygous G1792T substitution in the laminin G-type repeat domain, generating a premature stop codon at Glu598.

INTERVENTIONS

We considered that the inherited PS deficiency due to a PROS1 gene mutation may associate with recurrent VTE. The patient was suggested to have an extended anticoagulant therapy to avoid a severe VTE event.

OUTCOMES

The patient was discharged home with continued oral anticoagulants and was still seen in clinic for follow-up.

LESSONS

It is necessary for the young patient with recurrent idiopathic thrombosis to perform an inherited PS deficiency test and receive anticoagulant therapy for an extended period.

Thrombophilia Caused by Beta2-Glycoprotein I Deficiency: In Vitro Study of a Rare Mutation in APOH Gene

This study aimed to explore the mechanism of a novel mutation (p.Lys38Glu) in apolipoprotein H (APOH) gene causing hereditary beta2-glycoprotein I (β2GPI) deficiency and thrombosis in a proband with thrombophilia. The plasma level of β2GPI was measured by ELISA and Western blotting, and anti-β2GPI antibody by ELISA. Lupus anticoagulant (LA) was assayed using the dilute Russell viper venom time. Deficiency of the major natural anticoagulants including protein C (PC), protein S (PS), antithrombin (AT) and thrombomodulin (TM) was excluded from the proband. A mutation analysis was performed by amplification and sequencing of the APOH gene. Wild type and mutant (c.112A>G) APOH expression plasmids were constructed and transfected into HEK293T cells. The results showed that the thrombin generation capacity of the proband was higher than that of the other family members. Missense mutation p.Lys38Glu in APOH gene and LA coexisted in the proband. The mutation led to β2GPI deficiency and thrombosis by impairing the protein production and inhibiting the platelet aggregation. It was concluded that the recurrent thrombosis of the proband is associated with the coexistence of p.Lys38Glu mutation in APOH gene and LA in plasma.

Non-O blood group and outcomes of in vitro fertilization

PURPOSE

Retrospective and cross-sectional studies suggested that non-O blood group may be associated with failures of in vitro fertilization (IVF), but data remain controversial. The aim of this observational cohort study was to prospectively evaluate the effect of non-O blood type on clinical outcomes of IVF.

METHODS

Women < 40 years who underwent IVF and had ABO blood type recorded as part of the routine workup were eligible. The primary study outcome was live birth. Secondary outcomes included spontaneous abortion, positive pregnancy test, and clinical pregnancy.

RESULTS

A total of 497 women with a mean age of 34.6 (standard deviation 3.2) years were included. The mean number of embryos transferred was 2.3 (standard deviation 0.6). The most common ABO blood types were O (n = 213, 42.9%) and A (n = 203, 40.8%), while 63 (12.7%) and 18 (3.6%) women had the B and AB blood types, respectively. Differences in live birth (21.8 vs. 24.3%, odds ratio [OR] 1.17; 95% confidence intervals [CI], 0.76 to 1.78), positive pregnancy test (37.9 vs. 36.6%, OR 0.96; 95% CI, 0.66 to 1.38), clinical pregnancy (35.1 vs. 33.8%, OR 0.95; 95% CI, 0.66 to 1.39), and spontaneous abortion (12.3 vs. 9.2%, OR 0.72; 95% CI, 0.41 to 1.29) between women with O and non-O blood type were not statistically significant.

CONCLUSIONS

In a prospective cohort study, we confirmed the lack of a significant association between non-O blood type and clinical outcomes of IVF. Further studies are needed to clarify whether non-O blood group has any prognostic relevance in women undergoing IVF.

Incidence and risk factors for venous thromboembolism in patients with pretreated advanced pancreatic carcinoma

Patients with pancreatic carcinoma are at an increased risk of venous thromboembolism (VTE), which is a major cause of morbidity and mortality in various types of cancer. The aim of this study was to determine the incidence and clinical significance of VTE in patients with pancreatic carcinoma, and to identify biomarkers for the detection of VTE in these patients. The eligibility criteria were chemo-naïve patients with primary pancreatic carcinoma, an Eastern Cooperative Oncology Group performance status of 0–2, and adequate organ function. All patients were screened for VTE using compression ultrasonography and dynamic computed tomography. The primary endpoint was the incidence of VTE, which we hypothesized would be between 10.0–20.0% for symptomatic and asymptomatic patients combined. Associations between clinical presentation and VTE were evaluated. VTE-associated markers were also investigated for their role in predicting prognosis. In total, 103 patients met the eligibility criteria. The overall cumulative incidence rate of VTE in patients with previously untreated pancreatic carcinoma was 16.5%. VTE occurrence was strongly associated with elevated serum D-dimer, fibrin degradation product, thrombin/antithrombin III complex, and prothrombin fragment 1 + 2 levels. The median overall survival time of VTE-positive and VTE-negative patients was 427 and 515 days, respectively. Approximately one-sixth of patients with advanced pancreatic carcinoma experienced VTE, although most were asymptomatic. Measurement of serum D-dimer, fibrin degradation product, thrombin/antithrombin III complex, and prothrombin fragment 1 + 2 levels may be useful for the early detection of VTE in patients with advanced pancreatic carcinoma.

The diagnosis and treatment of venous thromboembolism in asian patients

Although the incidence of venous thromboembolism (VTE) in Asian populations is lower than in Western countries, the overall burden of VTE in Asia has been considerably underestimated. Factors that may explain the lower prevalence of VTE in Asian populations relative to Western populations include the limited availability of epidemiological data in Asia, ethnic differences in the genetic predisposition to VTE, underdiagnoses, low awareness toward thrombotic disease, and possibly less symptomatic VTE in Asian patients. The clinical assessment, diagnostic testing, and therapeutic considerations for VTE are, in general, the same in Asian populations as they are in Western populations. The management of VTE is based upon balancing the treatment benefits against the risk of bleeding. This is an especially important consideration for Asian populations because of increased risk of intracranial hemorrhage with vitamin K antagonists. Non-vitamin K antagonist oral anticoagulants have shown advantages over current treatment modalities with respect to bleeding outcomes in major phase 3 clinical trials, including in Asian populations. Although anticoagulant therapy has been shown to reduce the risk of postoperative VTE in Western populations, VTE prophylaxis is not administered routinely in Asian countries. Despite advances in the management of VTE, data in Asian populations on the incidence, prevalence, recurrence, risk factors, and management of bleeding complications are limited and there is need for increased awareness. To that end, this review summarizes the available data on the epidemiology, risk stratification, diagnosis, and treatment considerations in the management of VTE in Asia.

Reduced Protein C Global Assay Levels in Infertile Women with in vitro Fertilization Failure: A Pilot Study

Protein C global is a global dotting assay that evaluates abnormalities in the protein C anticoagulant pathway. A few studies have examined this assay in relation to assisted reproductive technology (ART), but its role in infertile women with in vitro fertilization (IVF) failure remains unclear. In this study, we assessed protein C in infertile women with a history of IVF failure who were undergoing ART. We examined 45 healthy fertile women who conceived naturally, and 45 infertile women with 2 or more implantation failures undergoing ART. Both protein C and activated protein C resistance (APC-R) were evaluated. The results showed that mean protein C expressed as a normalized ratio (PCAT-NR) was significantly lower in the study group compared to the control group (0.76 ± 0.15 vs. 0.91 ± 0.14, respectively; p = 0.0001). Follow-up on ART outcomes showed that women who failed ART had significantly lower PCAT-NR compared to successful cases. PCAT-NR did not correlate with APC-R levels in the study (r = 0.125, p < 0.5) or failed ART subgroups. Using logistic regression analysis, patients with lower PCAT-NR levels showed an elevated risk of implantation failure (p = 0.04, OR 0.50, 95% CI 0.26-0.84). In conclusion, protein C global assay may play a role in the etiology of IVF failure, which might be independent of APC-R. Larger studies are encouraged to validate these findings and explore the underlying pathophysiological mechanisms.

Anwendungen des endogenen Thrombinpotenzials

An overview is given on the method and the applications of thrombin generation assays. Thrombin generation assays provide a tool which can be used to trace the entire thrombin formation and inactivation of a plasma sample. Therefore they are principally different from traditional global assays like PT and aPTT and promise new opportunities for the assessment of bleeding or thrombotic risks.

Differential haemostatic risk factors for pregnancy-related deep-vein thrombosis and pulmonary embolism

Limited data exist on thrombophilia and the risk of venous thrombosis (VT) during pregnancy and postpartum. The objectives of the present study were to investigate the role of haemostatic risk factors for pregnancy-related VT and their phenotypic expression in deep-vein thrombosis (DVT) and pulmonary embolism (PE). Total 313 cases with objectively verified first time VT and 353 controls were selected from a source population of 377,155 women with 613,232 pregnancies. The adjusted odds ratio (aOR) for pregnancy-related VT was 1.7 (95% confidence interval [CI] 1.1–2.8) for women with factor VIII >90th percentile. The aOR for VT for endogenous thrombin potential and D-dimer values >90thpercentiles were 1.8 (95% CI 1.1–3.0) and 2.1 (95% CI 1.3–3.3), respectively. Factor IX >90thpercentile or free protein S ≤the 5th percentile increased the risk for PE, and the aORs were 2.4 (95% CI 1.1–5.0) and 3.1 (95% CI 1.3–7.2), respectively. Women carrying the factor V Leiden (F5 rs6025) polymorphism, or who had reduced sensitivity to activated protein C (aPC) in the absence of F5 rs6025, had increased risk for DVT, with unadjusted ORs 7.7 (95% CI 4.7–12.7) and 3.5 (95% CI 2.2–5.4), respectively. Women with a history of pregnancy-related VT showed activation of coagulation and had elevated factor VIII. Furthermore, high levels of factor IX and low levels of free protein S were associated with increased risk for PE, whereas aPC resistance and F5 rs6025 were risk factors for DVT and not PE.

Venous thromboembolism in Asia – an unrecognised and under-treated problem?

Venous thromboembolism (VTE) has been perceived for a long time to be less common in Asian populations, particularly in the Far East, than in Western populations. Generally, thromboprophylaxis is not implemented as frequently as it should be in high-risk patients. However, recent prospective studies undertaken in Asian countries have demonstrated higher rates of VTE after major surgery and in medical wards, approaching those observed in Western populations. Risk factors for VTE are not different in Asian patients from those of Western patients with the exception of thrombophilic mutations. Deficiencies of the natural anticoagulants (protein S, protein C, and antithrombin) are the predominant thrombophilias in Asia whereas factor V Leiden and prothrombin G20210A gene mutation are not found or rarely reported. Further large well-designed clinical studies are needed to evaluate the magnitude of the risk of VTE and the appropriate use of thromboprophylaxis in different clinical situations.

How I treat heterozygous hereditary antithrombin deficiency in pregnancy

Untreated hereditary antithrombin deficiency in pregnancy is associated with maternal venous thromboembolism (VTE) and possibly with fetal loss. Thromboprophylaxis during pregnancy is recommended, but dosages remain controversial. Our objective was to perform a retrospective assessment of thrombotic events and pregnancy outcomes in women with hereditary antithrombin deficiency managed according to a standard protocol. Pregnancies in individuals with hereditary antithrombin deficiency were identified from a hospital database. Women with no prior VTE received enoxaparin 40 mg daily until 16 weeks gestation and thereafter 40 mg twice daily. Women with prior VTE received intermediate dose enoxaparin (1 mg/kg) once daily, increased to twice daily at 16 weeks and anti-Xa monitored dosing. Thromboprophylaxis was stopped at initiation of labour or 12 hours prior to caesarean and 50 IU/kg antithrombin concentrate given. Thromboprophylaxis was restarted after delivery. Eighteen pregnancies in 11 women with antithrombin deficiency were identified. Seventeen pregnancies (94%) were successful. Median gestation was 39 weeks (range 30–41) and median birth-weight was 2,995 g (910–4,120 g),but 6/17 infants (35%) were small for gestational age (p=0.01). Estimated blood loss at delivery was median 375 ml (200–600 ml). Four pregnancies were complicated by VTE; one newly presented with a thrombotic event, two patients were not taking thromboprophylaxis and one occurred despite thromboprophylaxis. Two novel mutations(p.Leu317Ser and p.His33GInfsX32) are described. In conclusion, in antithrombin deficiency the use of low-molecular-weight heparin in pregnancy and puerperium with antithrombin concentrate predelivery was associated with successful pregnancy outcome; rates of VTE appear to be lower than previously reported, but remain elevated

Are Prothrombotic Mutations a Time-to-Event Risk Factor?

Background

Deep vein thrombosis (DVT) represents a common disorder involving genetic and acquired risk factors. It has been proposed that acquired risk factors are more important with aging than genetic factors, indicating different prevalence of prothrombotic mutations throughout the lifespan.

Objective

To determine the role of the most frequent prothrombotic genetic risk factors (Factor V [FV] Leiden and Factor II [FII] G20210A mutations) in first-time DVT etiology in patients of different ages.

Method

This retrospective study included 701 patients living in Serbia with diagnosed DVT as a first-time thrombotic event.

Results

Risk assessment for mutations as age-related markers showed no statistical difference (FV Leiden mutation-OR, 1.027; 95% confidence interval [CI], .87-1.22; P = .76 and FII G20210A mutation-OR, 0.940, 95% CI, .74-1.19; P = .61). Our results show similar mutation prevalence regardless of how old the patients were at the time of the first DVT occurrence.

Conclusion

Our results indicate that these 2 mutations cannot be used as prognostic marker for time-to-event first DVT in the Serbian population; however, further studies are required.

Recurrent mutations in a SERPINC1 hotspot associate with venous thrombosis without apparent antithrombin deficiency

Despite the essential anticoagulant function of antithrombin and the high risk of thrombosis associated with its deficiency, the prevalence of antithrombin deficiency among patients with venous thromboembolism (VTE) is very low. However, increasing evidence suggests that antithrombin deficiency may be underestimated. The analysis of SERPINC1, the gene encoding antithrombin, in 1,304 consecutive Chinese VTE patients and 1,334 healthy controls revealed a hotspot involving residues 294 and 295 that severely increases the risk of VTE. We detected the c.883G>A (p.Val295Met) (rs201381904) mutation in 11 patients and just one control (OR = 13.6; 95% CI: 1.7-107.1); c.881G>T (p.Arg294Leu) (rs587776397) in six patients but no controls; and c.880C>T (p.Arg294Cys) (rs747142328) in two patients but no controls. In addition, c.881G>A (p.Arg294His) (rs587776397) was identified in one control. These mutations were absent in a Caucasian cohort. Carriers of these mutations had normal antithrombin levels and anticoagulant activity, consistent with results obtained in a recombinant model. However, mutation carriers had a significantly increased endogenous thrombin potential. Our results suggest the existence in the Chinese population of a hotspot in SERPINC1 that significantly increases the risk of VTE by impairing the anticoagulant capacity of the hemostatic system. This effect is not revealed by current antigen or in vitro functional antithrombin assays.

Risk prediction of developing venous thrombosis in combined oral contraceptive users

Background

Venous thromboembolism (VTE) is a complex multifactorial disease influenced by genetic and environmental risk factors. An example for the latter is the regular use of combined oral contraceptives (CC), which increases the risk to develop VTE by 3 to 7 fold, depending on estrogen dosage and the type of progestin present in the pill. One out of 1'000 women using CC develops thrombosis, often with life-long consequences; a risk assessment is therefore necessary prior to such treatment. Currently known clinical risk factors associated with VTE development in general are routinely checked by medical doctors, however they are far from being sufficient for risk prediction, even when combined with genetic tests for Factor V Leiden and Factor II G20210A variants. Thus, clinical and notably genetic risk factors specific to the development of thrombosis associated with the use of CC in particular should be identified.

Methods and findings

Step-wise (logistic) model selection was applied to a population of 1622 women using CC, half of whom (794) had developed a thromboembolic event while using contraceptives. 46 polymorphisms and clinical parameters were tested in the model selection and a specific combination of 4 clinical risk factors and 9 polymorphisms were identified. Among the 9 polymorphisms, there are two novel genetic polymorphisms (rs1799853 and rs4379368) that had not been previously associated with the development of thromboembolic event. This new prediction model outperforms (AUC 0.71, 95% CI 0.69–0.74) previously published models for general thromboembolic events in a cross-validation setting. Further validation in independent populations should be envisaged.

Conclusion

We identified two new genetic variants associated to VTE development, as well as a robust prediction model to assess the risk of thrombosis for women using combined oral contraceptives. This model outperforms current medical practice as well as previously published models and is the first model specific to CC use.

Donor Selection and Prophylactic Strategy for Venous Thromboembolic Events in Living Donors of Liver Transplantation Based on Results of Thrombophilia Screening Tests

Background

We reported a strategy of thrombophilia testing-guided venous thromboembolic events (VTE) prophylaxis for living donors of liver transplantation in 2011. The aim of the present study was to evaluate the safety and efficacy of this protocol for VTE prophylaxis.

Material/Methods

Thrombophilia testing, including protein S (PS), protein C (PC), antithrombin (AT) III, and anti-phospholipid antibody (APLA), was performed in 306 living donor candidates between July 2005 and June 2016. Donors who met any of the criteria of PS <60%, PC <64%, AT-III <70%, and positive APLA were classified into the borderline group and received continuous venous infusion of heparin immediately after surgery, in addition to use of elastic stockings and intermittent pneumatic compression (IPC) until patients were ambulatory. Other donors who were classified into the normal group used elastic stockings and IPC with no anticoagulants. The efficacy and safety endpoints were VTE occurrence and bleeding events, respectively.

Results

PS was considerably decreased in 3 candidates and PC was considerably reduced in 1 candidate, and they were excluded for high risk of VTE. Seventeen candidates in the borderline group and 137 in the normal group underwent donor surgery. One donor in the borderline group developed a wound hematoma. Postoperative complications were similar between the 2 groups. None of the donors in either group developed VTE.

Conclusions

Thrombophilia testing-guided VTE prophylaxis is safe and may contribute to reduced VTE risk in donors, although further investigations are warranted to assess the necessity of thrombophilia testing prior to surgery among living donors.

Whole-exome sequencing in evaluation of patients with venous thromboembolism

Genetics play a significant role in venous thromboembolism (VTE), yet current clinical laboratory-based testing identifies a known heritable thrombophilia (factor V Leiden, prothrombin gene mutation G20210A, or a deficiency of protein C, protein S, or antithrombin) in only a minority of VTE patients. We hypothesized that a substantial number of VTE patients could have lesser-known thrombophilia mutations. To test this hypothesis, we performed whole-exome sequencing (WES) in 64 patients with VTE, focusing our analysis on a novel 55-gene extended thrombophilia panel that we compiled. Our extended thrombophilia panel identified a probable disease-causing genetic variant or variant of unknown significance in 39 of 64 study patients (60.9%), compared with 6 of 237 control patients without VTE (2.5%) (P < .0001). Clinical laboratory-based thrombophilia testing identified a heritable thrombophilia in only 14 of 54 study patients (25.9%). The majority of WES variants were either associated with thrombosis based on prior reports in the literature or predicted to affect protein structure based on protein modeling performed as part of this study. Variants were found in major thrombophilia genes, various SERPIN genes, and highly conserved areas of other genes with established or potential roles in coagulation or fibrinolysis. Ten patients (15.6%) had >1 variant. Sanger sequencing performed in family members of 4 study patients with and without VTE showed generally concordant results with thrombotic history. WES and extended thrombophilia testing are promising tools for improving our understanding of VTE pathogenesis and identifying inherited thrombophilias.

Optimal utilization of thrombophilia testing

The global incidence of venous thromboembolism is high so laboratory testing for hereditary thrombophilia and selected acquired thrombophilia is common. Given the costs associated with testing and multiple pre-analytic and analytic variables affecting the assays, careful patient selection and timing of testing and diligent application to patient management are critical to providing high-value clinical care. Collaboration between the ordering providers and performing laboratories has the potential to achieve these goals. Herein, utility of thrombophilia testing, variables that affect the assays, and impact on patient management are reviewed. Where available, information on cost-effectiveness is discussed.

R147W in PROC Gene Is a Risk Factor of Thromboembolism in Thai Children

The p.R147W mutation, the c.C6152T in exon 7, causing a change in amino acid from arginine to tryptophan of the PROC gene has been reported as a common mutation in Taiwanese populations with venous thromboembolism (VTE). The present study aimed to identify the prevalence of p.R147W in the Thai population and children with TE and the risk of developing TE. Patients aged ≤18 years diagnosed with TE were enrolled. The PROC gene was amplified by polymerase chain reaction using a specific primer in exon 7. The restriction fragment length polymorphism was designed using MwoI restriction enzyme. A total of 184 patients and 690 controls were enrolled. The most common diagnosis of TE was arterial ischemic stroke (AIS), at 100 (54.3%), followed by VTE, at 38 (20.6%), and cerebral venous sinus thrombosis (CVST), at 23 (12.5%). The prevalence of heterozygous and homozygous p.R147W in patients and controls was 9.5% versus 5.8% and 2.7% versus 0.1%, respectively. Heterozygous p.R147W had odds ratios (ORs) of 1.8 (95% confidence interval [CI]: 1.0-3.2, P = .04), 3.2 (95% CI: 1.2-8.2, P = .009), and 4.5 (95% CI: 1.6-12.8, P = .002) of developing overall TE, VTE, and CVST, respectively. Homozygous p.R147W had ORs of 20.2 (95% CI: 2.3-173.7, P < .001), 21.4 (95% CI: 2.2-207.9, P < .001), and 43.3 (95% CI: 3.8-490.6, P < .001) of developing overall TE, AIS, and CVST, respectively. This study suggested that p.R147W is a common mutation and increased risk of TE in Thai children.

Associations between polymorphisms in coagulation-related genes and venous thromboembolism: A meta-analysis with trial sequential analysis

BACKGROUND

Recently, several studies showed that the polymorphisms in the coagulation-related genes might be associated with venous thromboembolism (VTE); however, the results were still controversial. We performed a meta-analysis with trial sequential analysis to investigate the associations between the endothelial cell-activated protein C receptor (EPCR) rs9574, F11 rs2289252, F11 rs2036914, FGG rs2066865, FGG rs1049636, CYP4V2 rs13146272, SERPINC1 rs2227589, and GP6 rs1613662 polymorphisms with the risk of VTE.

METHODS

We searched both the common English-language databases and the Chinese literature databases. Two authors selected studies according to inclusion and exclusion criteria. Crude odds ratios with 95% confidence intervals (CI) were calculated to estimate the strength of this association. Between-study heterogeneity was assessed with the chi-square-based Q test and the I statistic.

RESULTS

Overall, a total of 20 studies were included. The meta-analysis revealed that the F11 rs2289252, F11 rs2036914, FGG rs2066865, and CYP4V2 rs13146272 polymorphisms were closely related to the development of VTE in the white race under the best genetic models after multiple testing adjustments. The EPCR rs9574, FGG rs1049636, SERPINC1 rs2227589, and GP6 rs1613662 polymorphisms might be potential candidates in the pathogenesis of VTE, but trial sequential analyses and sensitivity analyses indicated that the evidences were limited. Larger scale studies were demanded to avoid false-positive outcomes.

CONCLUSIONS

Finally, our study demonstrated the important role of rs2289252, rs2036914, rs2066865, and rs13146272 polymorphisms in the development of VTE in the white race. Rs9574, rs1049636, rs2227589 and rs1613662 polymorphisms might be risk factors of VTE. However, more studies involving diverse races are needed to probe the ethnic difference and the underlying mechanisms of significant associations.

A delayed presentation of homozygous protein C deficiency in a series of children: a report on two molecular defects

Pediatric emergency visits with purpura fulminans should raise the suspicion of hereditary homozygous protein C deficiency even beyond the neonatal age. The absence of this classical finding does not role the diagnosis out as atypical presentation with isolated intraocular bleeding was observed. Premarital counseling should be offered when family history suggests.

Cilioretinal artery: Vasculogenesis might be promoted by plasminogen activator inhibitor-1 5G allele

BACKGROUND

Cilioretinal arteries (CAs) represent enlargements of microscopic and early established collaterals formed via vasculogenesis between choroidal and retinal circulations. We aimed to investigate whether genetic tendency to thrombosis due to well-known gene polymorphisms may induce CA vasculogenesis in embryonic life.

METHODS

We assessed plasminogen activator inhibitor-1 (PAI-1) 4G/5G, methylenetetrahydrofolatereductase (MTHFR), FACTOR V LEIDEN and PROTHROMBIN gene polymorphisms on 130 patients [82/48 females/males; Median age: 57 (18-84) with visible CAs and 100 (64/36: female/male; Median age: 55 (19-90)] without visible CAs.

RESULTS

Using multiple logistic regression models, we found PAI-1 4G/5G; MTHFR (C677T and A1298C) polymorphisms to have significant effects on the probability of visible CAs, that having at least one 5G allele would increase the odds of having visible cilioretinal artery by 98.4% [Odds ratio: 1984 (95% CI: 1.320-3.000, p = 0.001)], and having at least one MTHFR C677T or A1298C allele would decrease the odds of having visible CAs by approximately 38% (OR = 0.618, 95% CI: 0.394-0.961, p = 0.035) or 44% (OR = 0.558, 95% CI: 0.354-0.871, p = 0.011), respectively.

CONCLUSIONS

This is the first study to test the existence of significant association between presence of enlarged and visible CAs and genetic factors predisposing to thrombosis, according to the literature. Here we suggest that not only the lack of genetic predisposition to thrombosis by MTHFR gene polymorphisms, but also the PAI-1 5G allele might promote vasculogenesis of CAs.

Polymorphisms of the coagulation system and risk of cancer

Hypercoagulability is a frequently finding in patients with cancer, and is associated with an increased risk of venous thrombosis (VT). Cancer-associated VT is associated with poor prognosis and represents the leading non-cancer cause of death among these patients. Conversely, patients experiencing VT are at increased risk of subsequent cancer, suggesting an epidemiological bidirectional link between cancer and hemostasis, and indicating a role of the hemostatic system in cancer development. How the coagulation system relates to cancer etiology at the genetic level is largely unexplored. Data on the association of polymorphisms in genes involved in coagulation with cancer development is important to clarify the role of the coagulation system in cancer pathogenesis. Effects of coagulation-related gene polymorphisms on cancer risk may possibly be translated into novel treatment- and prevention strategies of cancer-associated thrombosis and the cancer itself. This article reviews the current knowledge of the relation between polymorphisms in genes involved in coagulation and cancer risk in solid tumors.

Renal Papillary Necrosis Caused by Protein C Deficiency Leading to Recurrent Hydronephrosis

A patient with history of a solitary functioning kidney and protein C deficiency (PCD) presented with recurrent severe hydronephrosis causing acute kidney injury upon chronic kidney disease. Work-up with endoscopic evaluation revealed renal papillary necrosis (RPN) and sloughed renal papillae to be the true cause of the recurrent obstruction. Pathologic evaluation of the sloughed tissue confirmed the diagnosis of RPN. This is the first case reported in the literature illustrating the unique presentation of RPN in the setting of PCD.

Hypercoagulable States: A Review

Vascular surgeons are often asked to evaluate patients with recurrent thromboses or thromboses in unusual locations either arterial or venous. There may be obvious inciting factors, but in many of these patients the possibility of a previously undiagnosed hypercoagulable state must be considered. Hypercoagulable states can be acquired (smoking, medication, change in physiologic status as occurs with pregnancy) or congenital. Congenital hypercoagulable disorders are more prevalent in families or patients with a history of thromboembolic events early in life or multiple miscarriages and include conditions such as protein C or S deficiencies, factor V Leiden mutation, and prothrombin gene variant. This article reviews the hypercoagulable states that are encountered in clinical practice as well as guidelines for testing and goals of therapy.

Intracardiac Thrombosis and Acute Right Ventricular Failure Following Complex Reoperative Cardiac Surgery With Aprotinin and Deep Hypothermic Circulatory Arrest

Although coagulopathy and bleeding are common in the setting of cardiac surgery, a growing number of case reports in the literature suggest that hypercoagulability may also result in significant morbidity and mortality. We present a case of apparent hypercoagulability with formation of thrombus in the cardiac chambers following reoperative cardiac surgery using cardiopulmonary bypass, aprotinin, and deep hypothermic arrest. A review of those hypercoagulable disorders with reported impact on cardiac surgery and a discussion follow the case presentation.

Retinal vascular occlusion: a window to diagnosis of familial and acquired thrombophilia and hypofibrinolysis, with important ramifications for pregnancy outcomes

Aim

Our specific aim was to document the pathoetiologic importance of thrombophilia among females presenting with severe ischemic retinal vein (RVO) or retinal artery (RAO) occlusion, without typical risk factors, and to emphasize that the ophthalmologists’ diagnosis of thrombophilia has important diagnostic and therapeutic downstream ramifications for nonocular thrombosis, including reproductive outcomes.

Methods

We evaluated familial and acquired thrombophilia in 60 females with RVO (central RVO, n=52; branch RVO, n=8) and 16 with RAO (central RAO, n=11; branch RAO, n=5). They were referred by retinologists, without typical risk factors for RVO/RAO and/or severe ocular ischemic presentation. We focused on extraocular thrombotic events, particularly pregnancy complications, including unexplained spontaneous abortion, pre-eclampsia–eclampsia. Thrombophilia measurements in the 76 females were compared with 62 healthy normal females without ocular vascular occlusions (OVOs).

Results

The 76 females with OVO were more likely than 62 normal female controls to have high homocysteine (24% vs 0%, P<0.0001), high anticardiolipin antibody (immunoglobulin M, 17% vs 3%, P=0.012), high (>150%) factor VIII (42% vs 11%, P<0.0001), and high (>150%) factor XI (22% vs 4%, P=0.004). Of the 76 females, 26 (34%) had ≥1 spontaneous abortion; 17 (22%) had ≥2 spontaneous abortions and/or pre-eclampsia–eclampsia. Compared to 62 healthy female controls, these 17 females with pregnancy complications had high homocysteine (29% vs 0%, P=0.0003), high anticardiolipin antibody immunoglobulin M (24% vs 3%, P=0.02), high factor VIII (38% vs 11%, P=0.02), and were marginally more likely to be heterozygous for the factor V Leiden mutation (19% vs 3%, P=0.058).

Conclusion

In females lacking typical risk factors for retinal vascular occlusion or severely ischemic presentation, by diagnosing thrombophilia as an etiology for OVO, the ophthalmologist opens a window to family screening and preventive therapy, with particular relevance to pregnancy outcomes and venous thromboembolism.

Two novel compound heterozygous mutations associated with types I and II protein C deficiency with unusual phenotypes

INTRODUCTION

We diagnosed two Chinese hereditary PC deficiency families and identified two novel compound heterozygous mutations (p.Arg194Cys/Gly324Ser and p.Glu274X/Asp297His) in the protein C (PROC) gene. The probands were classified as types I and II PC deficiency. The aim of this article is to access the influence of the mutations on PC activity, antigen and protein structure, and to evaluate whether there is abnormal PC localization.

MATERIALS AND METHODS

Genomic DNA of all family members was extracted, PCR amplified, and sequenced. The mutant PC expression plasmids were constructed. Expression assays, intracellular localization, and molecular modeling were performed.

RESULTS

Proband 1, a type II PC defect, harbored a compound heterozygous mutation, p.Arg194Cys/Gly324Ser in the PROC gene, underwent two thromboembolic events. Expression assays indicated that the p.Arg194Cys mutant lead to decreased PC activity and normal PC Ag levels. Intracellular localization showed that both p.Arg194Cys and p.Gly324Ser co-localized with the endoplasmic reticuli and the Golgi apparatus. Molecular modeling suggested that the p.Gly324Ser mutation disturbed the interaction between the heavy and light chains of the PC protein. Proband 2, a type I PC defect, harbored a compound heterozygous PROC gene mutation, p.Glu274X/Asp297His, presented with recurrent spontaneous abortion and right popliteal vein thrombosis. Expression results were in accordance with the PC changes of the patient, and existed in defective PC transport. Structural model suggested p.Glu274X lead to disulfide bond between heavy and light chain cannot form.

CONCLUSIONS

Our results confirm that two novel compound heterozygous PROC gene mutations are causative on the two PC deficiency families.

A case-based reasoning view of thrombophilia risk

Thrombophilia stands for a genetic or an acquired tendency to hypercoagulable states that increase the risk of venous and arterial thromboses. Indeed, venous thromboembolism is often a chronic illness, mainly in deep venous thrombosis and pulmonary embolism, requiring lifelong prevention strategies. Therefore, it is crucial to identify the cause of the disease, the most appropriate treatment, the length of treatment or prevent a thrombotic recurrence. Thus, this work will focus on the development of a diagnosis decision support system in terms of a formal agenda built on a logic programming approach to knowledge representation and reasoning, complemented with a case-based approach to computing. The proposed model has been quite accurate in the assessment of thrombophilia predisposition risk, since the overall accuracy is higher than 90% and sensitivity ranging in the interval [86.5%, 88.1%]. The main strength of the proposed solution is the ability to deal explicitly with incomplete, unknown, or even self-contradictory information.

Prevalence of Prothrombin Gene Mutation (G-A 20210 A) in General Population: A Pilot Study

The objective of this study was to determine the prevalence of prothrombin gene mutation in a sample population from Pakistan. Two hundred apparently healthy unrelated adults (older than 18 years) were included in the study. The sample population comprised 100 Punjabis (male 50, female 50) and 100 Pathans (male 50, female 50). Patients with a history of previous thromboembolism were excluded from the study. Five milliliters (5 mL) of whole blood was drawn in an EDTA bottle. The DNA was extracted by the standard phenol-chloroform method. The DNA was amplified between exon number 14 and the 3’-untranslated region of the prothrombin gene by a polymerase chain reaction in a thermal cycler. Amplified products were digested overnight with HindIII at 37°C. The digested products were electrophoresed on 6% polyacrylamide gel. The fragments were visualized by silver nitrate staining. A heterozygous wild type and an uncut amplified product were included in the electrophoresis strip for quality control. The wild type of DNA ran as a 350-bp fragment and internal control was cut as 550- and 150-bp fragments. The abnormal prothrombin gene was cut into 350-, 322-, and 28-bp fragments. Only two cases of heterozygous prothrombin gene mutation G-A 20210A were found in the sample studied, giving an overall carrier rate of 01% (95% CI 0.4-2.4%) in the target population. Prothrombin gene mutation is present in our population but at a lower frequency than in the white population.

Vena Caval Filters: A Review for Intensive Care Specialists

Venous thromboembolism (VTE) is a common complication among patients in the intensive care unit. While anticoagulation remains standard therapy, vena caval filters are an important alternative when anticoagulation is contraindicated. To determine the safety and efficacy of vena caval filters in the treatment of VTE, a comprehensive review of the English-language medical literature was performed. Except for one randomized controlled trial, the literature supporting the use of vena caval filters consists almost exclusively of case series, which in many instances are limited by incomplete and short follow-up. While case series suggest that filters function effectively in the prevention of pulmonary embolism (2%-4% symptomatic pulmonary embolism [PE], fatal PE < 2%), recent higher quality studies indicate that filters may not provide significant additional protection to that provided by anticoagulation alone. Furthermore, filters are associated with a 2- fold increase in the incidence of recurrent DVT. Until randomized comparative studies are available, the safety and efficacy of all the available devices should be considered to be roughly equivalent. Since filters do not inhibit continued clot formation, all filter patients should receive anticoagulation for durations appropriate for their thrombotic disorder. Although extended anticoagulation may prevent thrombotic complications associated with filter placement, this strategy has yet to be experimentally tested. While many additional indications for vena caval filter use have been proposed (VTE in cancer patients, PE prophylaxis in trauma patients, etc), well-designed clinical trials demonstrating their efficacy in these situations are lacking. Further development of temporary/retrievable filters, which offer the potential to avoid the long-term complications of permanent filters, should be a research priority. Until additional data are available, vena caval filters should generally be restricted to patients with VTE who cannot receive anticoagulation.

Thrombophilia in Korean patients with arterial or venous thromboembolisms

Purpose

To determine the prevalence of thrombophilia in Korean patients with an arterial thromboembolism (ATE) or a venous thromboembolism (VTE), and to evaluate the characteristic of VTE in patients with thrombophilia.

Methods

Hospital records of 294 patients (228 with VTE, 66 with ATE) including two foreign ones (mean age, 51.4 years) who underwent thrombophilia testing between August 2006 and March 2015 were reviewed retrospectively. In general, such screening was performed according to the guidelines of the international consensus statement for VTE. Thrombophilia testing included evaluations of the factor V Leiden and prothrombin G20210A mutations, levels of proteins C and S and antithrombin, and antiphospholipid antibody syndrome (APLS).

Results

A factor V Leiden mutation was not found in the 292 Korean patients. A prothrombin G21210A mutation was investigated in 33 patients but none was found. Among 226 Korean patients with VTE, 130 demonstrated no thrombophilia and 55 patients did after exclusion of 41 patients without confirmatory test. The most common form was protein S deficiency (31 of 55, 56%) followed by protein C deficiency, antithrombin deficiency, and APLS. When comparing patients with a VTE or deep vein thrombosis (DVT) according to the presence of thrombophilia, thrombophilia was associated with younger age (P = 0.001 for VTE; P < 0.001 for DVT) and a family history (P < 0.001 for VTE and DVT).

Conclusion

We did not find any factor V Leiden mutation in Korean subjects at high risk for thrombophilia. Therefore, this testing is not warranted. Thrombophilia was associated with VTE in younger age and a family history.

Management of Venous Thromboembolisms: Part I. The Consensus for Deep Vein Thrombosis

Deep vein thrombosis (DVT) is a potentially catastrophic condition because thrombosis, left untreated, can result in detrimental pulmonary embolism. Yet in the absence of thrombosis, anticoagulation increases the risk of bleeding. In the existing literature, knowledge about the epidemiology of DVT is primarily based on investigations among Caucasian populations. There has been little information available about the epidemiology of DVT in Taiwan, and it is generally believed that DVT is less common in Asian patients than in Caucasian patients. However, DVT is a multifactorial disease that represents the interaction between genetic and environmental factors, and the majority of patients with incident DVT have either inherited thrombophilia or acquired risk factors. Furthermore, DVT is often overlooked. Although symptomatic DVT commonly presents with lower extremity pain, swelling and tenderness, diagnosing DVT is a clinical challenge for physicians. Such a diagnosis of DVT requires a timely systematic assessment, including the use of the Wells score and a D-dimer test to exclude low-risk patients, and imaging modalities to confirm DVT. Compression ultrasound with high sensitivity and specificity is the front-line imaging modality in the diagnostic process for patients with suspected DVT in addition to conventional invasive contrast venography. Most patients require anticoagulation therapy, which typically consists of parenteral heparin bridged to a vitamin K antagonist, with variable duration. The development of non-vitamin K oral anticoagulants has revolutionized the landscape of venous thromboembolism treatment, with 4 agents available,including rivaroxaban, dabigatran, apixaban, and edoxaban. Presently, all 4 drugs have finished their large phase III clinical trial programs and come to the clinical uses in North America and Europe. It is encouraging to note that the published data to date regarding Asian patients indicates that such new therapies are safe and efficacious. Ultimately, our efforts to improve outcomes in patients with DVT rely on the awareness in the scientific and medical community regarding the importance of DVT.

KEY WORDS

Combination therapy; Hypertension; α1-blocker.