Role of new anticoagulants for the prevention of venous thromboembolism after major orthopaedic surgery and in hospitalised acutely ill medical patients

Apixaban for Extended Thromboprophylaxis After Oncologic Resection: Outcomes and Cost Analysis

BACKGROUND

Patients undergoing oncologic resection are at risk of developing venous thromboembolism (VTE), and this can lead to increased morbidity and hospital costs. Low-molecular weight heparin (LMWH) is recommended as extended thromboprophylaxis (ETP) in high-risk patients and has been shown to reduce rates of VTE.

METHODS

This is a retrospective review of consecutive patients undergoing resection for oncologic indications at a single institution from May 2016 to May 2019. This study evaluated the use of apixaban as ETP at discharge. The primary outcomes were deep vein thrombosis (DVT), pulmonary embolism (PE), or mesenteric/portal venous thromboembolism at 30, 60, and 90 days postoperatively.

RESULTS

A total of 600 patients were included; 449 patients received no ETP, and 151 patients received apixaban. PE occurred in 1.1, 1.6, and 2.3% of patients without ETP and 0, 0, and .7% of patients in the apixaban group (at 30, 60, and 90 days; P = .338, P = .201, and P = .306, respectively). DVT occurred in 1.8, 2.1, and 2.8% of patients without ETP and 0, 0, and 1.4% in the apixaban group (P = .211, P = .121, and P = .535, respectively). The total cost, including ETP and readmission for VTE, per patient was US $5.51 more in the apixaban group.

CONCLUSION

Apixaban therapy for ETP did not produce a statistically significant reduction in VTE events in our patients. Future studies should include more patients in a prospective multicenter trial.

SPIONs and magnetic hybrid materials: Synthesis, toxicology and biomedical applications

In the past decades, a wide variety of different superparamagnetic iron oxide nanoparticles (SPIONs) have been synthesized. Due to their unique properties, such as big surface-to-volume ratio, superparamagnetism and comparatively low toxicity, they are principally well suited for many different technical and biomedical applications. Meanwhile, there are a numerous synthesis methods for SPIONs, but high requirements for biocompatibility have so far delayed a successful translation into the clinic. Moreover, depending on the planned application, such as for imaging, magnetic drug targeting, hyperthermia or for hybrid materials intended for regenerative medicine, specific physicochemical and biological properties are inevitable. Since a summary of all existing SPION systems, their properties and application is far too extensive, this review reports on selected methods for SPION synthesis, their biocompatibility and biomedical applications.

Assessment of direct oral anticoagulants administered as potentially inappropriate medications to elderly inpatients

Background There is evidence that direct oral anticoagulants administered as potentially inappropriate medications increase the risk of bleeding and thromboembolic complications, which represent serious threats to human health. Objective To identify direct oral anticoagulants administered as potentially inappropriate medications for hospitalized patients aged ≥ 65 years in our hospital, and to determine associated factors and the correlation between potentially inappropriate medications and adverse reactions. Setting Xi'an Central Hospital, China. Method A retrospective cross-sectional study of elderly hospitalized patients who received either dabigatran or rivaroxaban at Xi'an Central Hospital between June 1, 2018 and June 1, 2019. The evaluation criteria of direct oral anticoagulants were formulated based on drug labels, disease guidelines and the 2019 American Geriatrics Society Beers Criteria, and any non-compliance with the criteria was considered to be potentially inappropriate medications. The Pearson chi-square test and a binary logistic regression model were used. Main outcome measure Factors associated with potentially inappropriate medications and correlation between potentially inappropriate medications and adverse reactions. Results This study analysed 315 patients aged ≥ 65 years. The application of our evaluation criteria identified 155 (49.2%) instances of potentially inappropriate medications, comprising 5 different types of potentially inappropriate medications. Fifteen adverse drug reactions occurred in the study participants. The Pearson chi-square test revealed significant differences in number of medications (p = 0.021) and creatinine clearance rate (p = 0.002) between potentially inappropriate medications and non-potentially inappropriate medications groups. In the binary logistic regression model, potentially inappropriate medications use was associated with creatinine clearance (creatinine clearance < 30: OR = 3.590, 95% CI = 1.214-10.615, p = 0.021), and there was no significant correlation between potentially inappropriate medications and adverse drug reactions after eliminating the confounding factors (age, length of hospitalization, number of disease combined) with p values of less than 0.25 (adjusted OR = 0.372, 95% CI = 0.117-1.182, p = 0.094). Conclusion This study revealed that the incidence of potentially inappropriate medications was relatively high, number of medications and creatinine clearance differed significantly between potentially inappropriate medications and non-potentially inappropriate medications groups, and potentially inappropriate medications was associated with creatinine clearance (creatinine clearance < 30 mL/min), but there was no significant correlation between potentially inappropriate medications and adverse drug reactions after eliminating the confounding factors.

Prevention and treatment of venous thromboembolism in hospital and the community: a research programme including the ExACT RCT

Background

Deep-vein thrombosis and pulmonary embolism, collectively known as venous thromboembolism when clots are formed in the venous circulation, are common disorders that are often unprovoked (i.e. there is no obvious reason for the clot occurring). Some people, after having an unprovoked clot, are at a high risk of developing another, or at risk of developing a secondary clot, most importantly in the lungs. Furthermore, in the long term, some patients will develop circulation problems known as post-thrombotic syndrome. The aim of this programme was to improve the understanding of both the prevention and the treatment of thrombosis in people at the highest risk of recurrence.

Objectives

To clarify if it is possible to identify those people at the highest risk of having a recurrent venous thromboembolism, and if it is possible to prevent this happening by giving anticoagulation treatment for longer. To clarify if it is possible to identify those people at the highest risk of developing post-thrombotic syndrome. To document the current knowledge level about prevention and treatment of venous thromboembolism. To find what the barriers are to implementing measures to prevent venous thromboembolism. To find the most cost-effective means of treating venous thromboembolism.

Design

Mixed methods, comprising a randomised controlled trial, qualitative studies, cost-effectiveness analyses and questionnaire studies, including patient preferences.

Setting

UK general practices and hospitals, predominantly from the Midlands and Shropshire.

Participants

Adults attending participating anticoagulation clinics with a diagnosis of first unprovoked deep-vein thrombosis or pulmonary embolism, and health-care professionals, patients and other stakeholders who were involved in the prevention and treatment of venous thromboembolism.

Intervention

Extended treatment with oral anticoagulation therapy (2 years) versus standard care (treatment with oral anticoagulation therapy for at least 3 months).

Results

Work package 1 demonstrated that extended anticoagulation for up to 2 years was clinically effective and cost-effective in reducing the incidence of recurrent venous thromboembolism, with a small increase in the risk of bleeding. There was no difference in post-thrombotic syndrome incidence or severity, or quality of life, between those undergoing the extended treatment and those receiving the standard care. Work package 2 identified five common themes with regard to the prevention of hospital-acquired thrombosis: communication, knowledge, role of primary care, education and training, and barriers to patient adherence. Work package 3 suggested that extended anticoagulation with novel oral anticoagulants was cost-effective only at the £20,000-per-quality-adjusted life-year level for a recurrence rate of between 17.5% and 22.5%, depending on drug acquisition costs, while identifying a strong patient preference for extended anticoagulation based on a fear of recurrent venous thromboembolism.

Limitations

The major limitation was the failure to reach the planned recruitment target for work package 1.

Conclusions

Extended anticoagulation with warfarin for a first unprovoked venous thromboembolism is clinically effective and cost-effective and is strongly preferred by patients to the alternative of not having treatment. There are significant barriers to the implementation of preventative measures for hospital-acquired thrombosis. Further research is required on identifying patients in whom it is safe to discontinue anticoagulation, and at what time point following a first unprovoked venous thromboembolism this should be done.

Trial registration

Current Controlled Trials ISRCTN73819751 and EudraCT 2101-022119-20.

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full in Programme Grants for Applied Research; Vol. 8, No. 5. See the NIHR Journals Library website for further project information.

Thromboprophylactic Efficacy and Safety of Anticoagulants After Arthroscopic Knee Surgery: A Systematic Review and Meta-Analysis

To examine the efficacy and safety of anticoagulants after knee arthroscopy (KA), PubMed, EMBASE, databases of Cochrane Central Register of Controlled Trials, and Chinese National Knowledge Infrastructure were searched up to August 2019 for randomized controlled trials (RCT). Seven RCTs including 4097 patients were demonstrated eligible according to the inclusion and exclusion criteria. The efficacy and safety of thromboprophylaxis were assessed and expressed using relative risk (RR) and 95% confidence intervals (95% CIs). The analysis of pooled data showed that anticoagulants group exhibited significant lower overall incidence of symptomatic and asymptomatic venous thromboembolism (VTE; RR = 0.35, 95% CIs: 0.22-0.55, P < .00001), significant higher incidence of all bleeding events (RR = 1.42, 95% CIs: 1.08-1.86, P = .01) compared to control group. However, no significant difference was found in terms of incidence of symptomatic VTE (RR = 0.43, 95% CIs: 0.15-1.21, P = .11) and incidence of major bleeding events (RR = 1.87, 95% CIs: 0.40-8.67, P = .42). The pooled number needed to treat to prevent one symptomatic or asymptomatic VTE was 26, while the pooled number needed to harm to cause one major bleeding event was 869. These results show that anticoagulants can effectively reduce the overall risk of VTE after KA; however, the increased risk of bleeding should be fully considered. Further studies are required to address the risk–benefit calculus and cost-effectiveness of anticoagulants after KA.

Angiotensin II promotes the anticoagulant effects of rivaroxaban via angiotensin type 2 receptor signaling in mice

Rivaroxaban is an oral direct factor Xa inhibitor approved for the treatment of stroke and systemic thromboembolism in patients with non-valvular atrial fibrillation. Despite its efficacy, rivaroxaban therapy results in adverse effects and complications, such as bleeding. Angiotensin II (AngII) is implicated in many cardiovascular conditions, such as hypertension and heart failure. In this study, we investigate whether AngII influences anticoagulant effects of rivaroxaban by using an experimental mouse model with type 2 diabetes mellitus and advanced glycation end product (AGE)-exposed human umbilical vein endothelial cells (HUVECs). We found that AngII promoted the anticoagulant effects of rivaroxaban in KKAy mice. The combination of rivaroxaban and AngII enhanced in vivo tissue factor pathway inhibitor (TFPI) activity and induced TFPI expression and activity in AGE-exposed HUVECs. Angiotensin type 2 receptor (AT2R) and Mas antagonists attenuated the AngII-enhanced anticoagulant action of rivaroxaban in vivo, and abolished the increased endothelial TFPI expression and activity. However, angiotensin type 1 receptor (AT1R) antagonist exerted no effects. Additionally, combination of rivaroxaban and AngII induced aortic AT2R and Mas expression. Our data suggest that the anticoagulant effects of rivaroxaban are promoted by AngII via AT2R and Mas signaling. These findings are significant for the clinical administration of rivaroxaban.

Platelets in cancer metastasis: To help the "villain" to do evil

Cancer progress is accompanied by platelet activation and thrombotic complications. Platelets are a dangerous alliance of cancer cells, and are a close engager in multiple processes of cancer metastasis. Platelet adhesion to cancer cells forms a protective cloak that helps cancer cells to escape immune surveillance and natural killer cell-mediated cytolysis. Platelets facilitate tethering and arrest of disseminated cancer cells in the vasculature, enhance invasive potentials and thus extravasation of cancer cells. Moreover, platelets recruit monocytes and granulocytes to the sites of cancer cell arrest, and collaborate with them to establish a pro-metastatic microenvironment and metastatic niches. Platelets also secret a number of growth factors to stimulate cancer cell proliferation, release various angiogenic regulators to regulate tumor angiogenesis and subsequently promote cancer growth and progress. Albeit platelets are helping the "villain" cancer to do evil, the close engagements of platelets in cancer metastasis and progress can be used as the intervention targets for new anti-cancer therapeutic developments. Platelet-targeted anti-cancer strategy may bring in novel anti-cancer treatments that can synergize the therapeutic effects of chemotherapies and surgical treatments of cancer.

Thrombosis: Novel nanomedical concepts of diagnosis and treatment

Intravascular thrombosis, a critical pathophysiological feature of many cardiovascular disorders, leads to the formation of life-threatening obstructive blood clots within the vessels. Rapid recanalization of occluded vessels is essential for the patients’ outcome, but the currently available systemic fibrinolytic therapy is associated with low efficacy and tremendous side effects. Additionally, many patients are ineligible for systemic thrombolytic therapy, either due to delayed admission to the hospital after symptom onset, or because of recent surgery, or bleeding. In order to improve the treatment efficacy and to limit the risk of hemorrhagic complications, both precise imaging of the affected vascular regions, and the localized application of fibrinolytic agents, are required. Recent years have brought about considerable advances in nanomedical approaches to thrombosis. Although these thrombus-targeting imaging agents and nanotherapies are not yet implemented in humans, substantial amount of successful in vivo applications have been reported, including animal models of stroke, acute arterial thrombosis, and pulmonary embolism. It is evident that the future progress in diagnosis and treatment of thrombosis will be closely bound with the development of novel nanotechnology-based strategies. This Editorial focuses on the recently reported approaches, which hold a great promise for personalized, disease-targeted treatment and reduced side effects in the patients suffering from this life-threatening condition.

Rivaroxaban, a novel oral anticoagulant, attenuates atherosclerotic plaque progression and destabilization in ApoE-deficient mice

OBJECTIVE

Activated factor X (FXa) plays a key role in the coagulation cascade, whereas accumulating evidence suggests that it also contributes to the pathophysiology of chronic inflammation on the vasculature. In this study, we assessed the hypothesis that rivaroxaban (Riv), a direct FXa inhibitor, inhibits atherogenesis by reducing macrophage activation.

METHODS AND RESULTS

Expression levels of PAR-1 and PAR-2, receptors for FXa, increased in the aorta of apolipoprotein E-deficient (ApoE(-/-)) mice compared with wild-type mice (P < 0.01, P < 0.05, respectively). Administration of Riv (5 mg/kg/day) for 20 weeks to 8-week-old ApoE(-/-) mice reduced atherosclerotic lesion progression in the aortic arch as determined by en-face Sudan IV staining compared with the non-treated group (P < 0.05) without alteration of plasma lipid levels and blood pressure. Histological analyses demonstrated that Riv significantly decreased lipid deposition, collagen loss, macrophage accumulation and matrix metallopeptidase-9 (MMP-9) expression in atherosclerotic plaques in the aortic root. Quantitative RT-PCR analyses using abdominal aorta revealed that Riv significantly reduced mRNA expression of inflammatory molecules, such as MMP-9, tumor necrosis factor-α (TNF-α). In vitro experiments using mouse peritoneal macrophages or murine macrophage cell line RAW264.7 demonstrated that FXa increased mRNA expression of inflammatory molecules (e.g., interleukin (IL)-1β and TNF-α), which was blocked in the presence of Riv.

CONCLUSIONS

Riv attenuates atherosclerotic plaque progression and destabilization in ApoE(-/-) mice, at least in part by inhibiting pro-inflammatory activation of macrophages. These results indicate that Riv may be particularly beneficial for the management of atherosclerotic diseases, in addition to its antithrombotic activity.

Current practice of venous thromboembolism prevention in acute trusts: a qualitative study

OBJECTIVE

To explore the current practice of venous thromboembolism (VTE) prevention in acute trusts.

DESIGN

A qualitative research design was used to explore the perceived current practice of thromboprophylaxis, and knowledge and experience of VTE prevention. Data were collected via interviews with personnel from acute trusts and other relevant organisations and charities. Constant comparison was used to generate themes grounded in the data.

SETTING

The UK.

PARTICIPANTS

17 participants, sampled due to their expertise and knowledge in the field of VTE, were interviewed for the study.

RESULTS

No one felt directly responsible for VTE risk assessment and treatment in acute trusts. There were concerns whether any action takes place based on the risk assessment. Low levels of VTE knowledge existed throughout the system.

CONCLUSIONS

Our study highlights the importance of continuous training to prevent VTE risk assessment being considered a tick box exercise and for clinicians to understand the significance of the procedure to ensure that VTE preventative measures are administered. It is essential that acute trust staff acknowledge that VTE prevention is the responsibility of everyone involved in a patient's care. Concerns remain around prophylaxis treatment, administration and contraindications.

Heparin for the prevention of venous thromboembolism in acutely ill medical patients (excluding stroke and myocardial infarction)

BACKGROUND

Venous thromboembolic disease has been extensively studied in surgical patients. The benefit of thromboprophylaxis is now generally accepted, but it is medical patients who make up the greater proportion of the hospital population. Medical patients differ from surgical patients with regard to their health and the pathogenesis of thromboembolism and the impact that preventative measures can have. The extensive experience from thromboprophylaxis studies in surgical patients is therefore not necessarily applicable to non-surgical patients. This is an update of a review first published in 2009.

OBJECTIVES

To determine the effectiveness and safety of heparin (unfractionated heparin or low molecular weight heparin) thromboprophylaxis in acutely ill medical patients admitted to hospital, excluding those admitted to hospital with an acute myocardial infarction or stroke (ischaemic or haemorrhagic) or those requiring admission to an intensive care unit.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched November 2013) and CENTRAL (2013, Issue 10).

SELECTION CRITERIA

Randomised controlled trials comparing unfractionated heparin (UFH) or low molecular weight heparin (LMWH) with placebo or no treatment, or comparing UFH with LMWH.

DATA COLLECTION AND ANALYSIS

One review author identified possible trials and a second review author confirmed their eligibility for inclusion in the review. Two review authors extracted the data. Disagreements were resolved by discussion. We performed the meta-analysis using a fixed-effect model with the results expressed as odds ratios (ORs) with 95% confidence intervals (CIs).

MAIN RESULTS

Sixteen studies with a combined total of 34,369 participants with an acute medical illness were included in this review. We identified 10 studies comparing heparin with placebo or no treatment and six studies comparing LMWH to UFH. Just under half of the studies had an open-label design, putting them at a risk of performance bias. Descriptions of random sequence generation and allocation concealment were missing in most of the studies. Heparin reduced the odds of deep vein thrombosis (DVT) (OR 0.38; 95% CI 0.29 to 0.51; P < 0.00001). The estimated reductions in symptomatic non-fatal pulmonary embolism (PE) (OR 0.46; 95% CI 0.19 to 1.10; P = 0.08), fatal PE (OR 0.71; 95% CI 0.43 to 1.15; P = 0.16) and in combined non-fatal PE and fatal PE (OR 0.65; 95% CI 0.42 to 1.00; P = 0.05) associated with heparin were imprecise. Heparin resulted in an increase in major haemorrhage (OR 1.81; 95% CI 1.10 to 2.98; P = 0.02). There was no clear evidence that heparin had an effect on all-cause mortality and thrombocytopaenia. Compared with UFH, LMWH reduced the risk of DVT (OR 0.77; 95% CI 0.62 to 0.96; P = 0.02) and major bleeding (OR 0.43; 95% CI 0.22 to 0.83; P = 0.01). There was no clear evidence that the effects of LMWH and UFH differed for the PE outcomes, all-cause mortality and thrombocytopaenia.

AUTHORS' CONCLUSIONS

The data from this review describe a reduction in the risk of DVT in patients presenting with an acute medical illness who receive heparin thromboprophylaxis. This needs to be balanced against an increase in the risk of bleeding associated with thromboprophylaxis. The analysis favoured LMWH compared with UFH, with a reduced risk of both DVT and bleeding.

Administration of enoxaparin 24 h after total knee arthroplasty: safer for bleeding and equally effective for deep venous thrombosis prevention

BACKGROUND

The purpose of this study was to determine the safety and effectiveness, as assessed by risk of bleeding and incidence of deep venous thrombosis (DVT), of administering delayed low-molecular-weight heparin (LMWH) after total knee arthroplasty.

METHODS

A prospective study of 210 consecutive patients undergoing primary unilateral total knee arthroplasty was undertaken. The patients were randomized into two groups: one of which was managed according to a standard LMWH program (LMWH-s group) and the other with delayed LMWH (LMWH-p). LMWH was initiated 12 h after wound closure in the LMWH-s group, and 24 h after wound closure in the LMWH-p group.

RESULTS

The total blood loss in the first three postoperative days was calculated and all complications were recorded. The mean total blood loss was 435 and 387 mL in the LMWH-s group and LMWH-p group, respectively (p < 0.01). No significant difference in the incidence of symptomatic DVT was observed. The mean length of hospital stay was 7.29 days in the LMWH-s group and 6.56 days in the LMWH-p group (p < 0.05).

CONCLUSIONS

After total knee arthroplasty, LMWH-p is safer for bleeding than LMWH-s and equally effective concerning prevention of DVT.

Pharmacokinetics of recombinant human antithrombin in delivery and surgery patients with hereditary antithrombin deficiency

Population pharmacokinetic (PK) analyses were conducted to refine dosing recommendations for recombinant human anti-thrombin therapy in surgery and delivery patients with hereditary antithrombin deficiency (HD). Single-dose PK data from patients with HD and nonlinear mixed-effects modeling were used to devise a dosing regimen to target antithrombin (AT) activity levels between 80% and 120% of normal. External validation with data from a phase 3 trial confirmed the correctness of a covariate-free model for surgery patients, but dosing adjustment was necessary for delivery patients. After different covariates were tested, the model was updated to incorporate the influential covariate, delivery. Simulations were used to develop a therapeutic drug-monitoring scenario that results in steady state AT activity levels within the target range as quickly as practically feasible. Data from a second clinical trial provided additional external validation and confirmed the accuracy of the dosing model for both groups of patients.

Prevention of venous thromboembolism in acutely ill medical patients after the results of recent trials with the new oral anticoagulants

Venous thromboembolism (VTE) is a common potentially life-threatening complication in acutely ill medical patients; over 70 % of the fatal episodes of pulmonary embolism during hospitalization occur in non-surgical patients. In the absence of thromboprophylaxis, the incidence of venographically detected deep vein thrombosis is about 15 % in medical patients. Several trials and meta-analyses have clearly demonstrated the prophylactic role of unfractionated heparin, low molecular weight heparin and fondaparinux. Although over the past few years the knowledge of epidemiology, clinical features and prophylaxis in medical patients has significantly improved, there remain a number of controversial areas that require further investigation. Newer VTE risk assessment models have been proposed to select high risk hospitalized medical patients, but they still require external validation; scarce data are available to stratify patients to identify their individual bleeding risk. The optimal duration of thromboprophylaxis in medical patients is still a matter of debate; currently, extended prophylaxis after discharge is not recommended, but it may be required for subgroup of patients with persistently high VTE risk and a negligible risk of bleeding. Based on the results of recent studies, the new oral anticoagulants appear to have a very limited role, if any. However, a better risk stratification of patients who have a persistently increased risk of VTE is warranted to improve the risk to benefit profile of any anticoagulant drug to be used in this setting.

The study of the thrombin generation mechanism and the effect of low molecular weight heparin as thromboprophylaxis in patients undergoing total knee and hip replacement

INTRODUCTION

The recommended duration of post-operative Low-Molecular-Weight-Heparins (LMWHs) thromboprophylaxis in Total-Hip-Replacement (THR) and Total-Knee-Replacement (TKR) surgery is controversial. Our aim is to study the thrombin generation (TG) modifications induced by surgery and to evaluate the effect of LMWH on TG during and after the recommended duration.

PATIENTS/METHODS

Thirty-one patients received 4000IU anti-Xa/day of enoxaparin, 8-hours post-operatively (15 THR for 30-days and 16 TKR for 15-days). TG assay sensitive to enoxaparin was performed, pre-operatively (D0), 7-hours post-surgery (D1), 8-days post-surgery (D8), and 2-days after thromboprophylaxis withdrawal (D32 and D17), evaluating: lag-time, endogenous thrombin potential (ETP), peak amount of generated thrombin (Peak), time-to-Peak (tt-Peak), and the Mean-Rate-Index [MRI=Peak/(tt-Peak-lag-time)].

RESULTS

TKR surgery decreased lag-time and tt-Peak and increased MRI on D1 vs D0 (p<0.05). In contrast, THR did not significantly modify TG. Enoxaparin effectively reduced thrombin generation in both groups. Thromboprophylaxis withdrawal resulted in rebound increase of TG in the TKR patients (ETP, Peak & MRI significantly increased on D17 vs D0; p<0.05, and vs. D1; p<0.05) but not in THR patients. Variability in the response to enoxaparin was observed among patients of the same group.

CONCLUSIONS

TKR surgery is more thrombogenic than THR surgery. In THR patients TG was efficiently inhibited by 30-day thromboprophylaxis, whereas, in TKR patients treated for 15-days TG was not effectively inhibited. Individual variability of the response to enoxaparin was observed in both groups revealing some form of biological resistance to enoxaparin. TG assay may represent the breakthrough step to efficient antithrombotic strategy in clinical settings with high thrombotic risk.

The incidence of pulmonary embolism during deep vein thrombosis

Among life-threatening cardiovascular diseases, pulmonary embolism (PE) is the third most common after myocardial infarction and stroke. PE is a manifestation of venous thromboembolism (VTE). PE shares risk factors with deep vein thrombosis (DVT) and is regarded as a consequence of DVT rather than a separate clinical entity. Risk factors for VTE include major surgery, major trauma, high age, myocardial infarction, chronic heart failure, prolonged immobility, malignancy, thrombophilia and prior VTE. It is, however, important to recognize that these factors are not equally important and not equally common in patients with PE and DVT, respectively. Compared with DVT, PE is more often associated with major surgery, major trauma, high age, myocardial infarction and chronic heart failure, whereas malignancy and thrombophilia primarily are clinical predictors of DVT. In patients with prior VTE the initial clinical manifestation strongly predicts the manifestation of recurrent episodes, i.e. patients with previous PE are more likely to develop recurrent PE than DVT while patients with DVT predominantly are at risk of recurrent DVT.