Pre-operative Plasma Levels of Thrombin-Antithrombin III Complexes Correlate with the Development of Venous Thrombosis after Major Hip or Knee Surgery

Targeted proteomics for evaluating risk of venous thrombosis following traumatic lower-leg injury or knee arthroscopy

INTRODUCTION

Patients with lower-leg cast immobilization and patients undergoing knee arthroscopy have an increased risk of venous thrombosis (VT). Guidelines are ambiguous about thromboprophylaxis use, and individual risk factors for developing VT are often ignored. To assist in VT risk stratification and guide thromboprophylaxis use, various prediction models have been developed. These models depend largely on clinical factors and provide reasonably good C-statistics of around 70%. We explored using protein levels in blood plasma measured by multiplexed quantitative targeted proteomics to predict VT. Our aim was to assess whether a VT risk prediction model based on absolute plasma protein quantification is possible.

METHODS

We used internal standards to quantify proteins in less than 10 μl plasma. We measured 270 proteins in samples from patients scheduled for knee arthroscopy or with lower-leg cast immobilization. The two prospective POT-(K)CAST trails allow complementary views of VT signature in blood, namely pre and post trauma, respectively. From approximately 3000 patients, 31 patients developed VT who were included and matched with double the number of controls.

RESULTS

Top discriminating proteins between cases and controls included APOC3, APOC4, APOC2, ATRN, F13B, and F2 in knee arthroscopy patients and APOE, SERPINF2, B2M, F13B, AFM, and C1QC in patients with lower-leg cast. A logistic regression model with cross-validation resulted in C-statistics of 88.1% (95% CI: 85.7-90.6%) and 79.6% (95% CI: 77.2-82.0%) for knee arthroscopy and cast immobilization groups respectively.

CONCLUSIONS

Promising C-statistics merit further exploration of the value of proteomic tests for predicting VT risk upon additional validation.

Changes in Biomarkers of Coagulation, Fibrinolytic, and Endothelial Functions for Evaluating the Predisposition to Venous Thromboembolism in Patients With Hereditary Thrombophilia

The changes in the coagulation, fibrinolytic, and endothelial functions are correlated with the pathophysiology of the thromboembolic diseases during acute illness. However, these changes in patients with hereditary thrombophilia who were not in the acute stage of venous thromboembolism (VTE) are unclear. A panel of 4 biomarkers, including thrombin–antithrombin complex (TAT), plasmin-α2-plasmin inhibitor complex (PIC), tissue-type plasminogen activator/plasminogen activator inhibitor-1 complex (t-PAIC), and soluble thrombomodulin (sTM), were assayed in 100 healthy controls and 100 patients with thrombophilia. Although significantly higher concentrations of TAT, PIC, t-PAIC, and sTM were observed in patients with thrombophilia than in healthy controls, 70 patients showed absolutely normal levels of the above 4 biomarkers. Among the other 30 patients who had at least 1 biomarker out of the corresponding reference interval, 26 of them presented elevated PIC with or without increased TAT. Except for sTM, other 3 biomarkers did not show significant differences in patients with previous VTE compared to those without. Patients with single episode of VTE had obviously lower t-PAIC than those with multiple episodes of VTE, whereas the levels of TAT, PIC, and sTM were unassociated with the number of thrombosis episodes. Most thrombophilia patients who were not in the acute stage of VTE showed normal coagulation, fibrinolytic, and endothelial functions. Thus, we were unable to show that the one-time response of this panel was clinically helpful in determining thrombosis risk in thrombophilia individuals. Future studies should focus on the dynamic monitoring during the chronic phase of VTE to offer special advantages for patients with thrombophilia.

Incidence and locations of deep venous thrombosis of the lower extremity following surgeries of tibial plateau fractures: a prospective cohort study

OBJECTIVE

To investigate the incidence of deep venous thrombosis (DVT) of the lower extremities following surgeries of tibial plateau fractures.

METHODS

Retrospective analysis of the prospectively collected data on patients undergoing surgeries of tibial plateau fractures between October 2014 and December 2018 was conducted. Duplex ultrasonography (DUS) was used to screen for postoperative DVT of the bilateral lower extremities. Data on demographics, comorbidities, injury, surgery, and laboratory biomarkers at admission were collected. Univariate analyses and multivariate logistic regression analyses were used to identify the independent risk factors associated with DVT.

RESULTS

Among 987 patients included, 46 (4.7%) had postoperative DVT, with incidence rate of 1.0% for proximal and 3.7% for distal DVT. The average interval between operation and DVT was 8.3 days (median, 5.8 days), ranging from 2 to 42 days. DVT involved the injured extremity in 39 (84.8%) patients, both the injured and uninjured extremity in 2 patients (4.3%) and only the uninjured extremity in 5 patients (10.9%). Five risk factors were identified to be associated with postoperative DVT, including age (≥ 41 vs < 41 years) (OR 3.08; 95% CI 1.43-6.61; p = 0.004), anesthesia (general vs regional) (OR 2.08; 95% CI 1.12-3.85; p = 0.021), hyponatremia (OR 2.21; 95% CI 1.21-4.06; p = 0.010), prolonged surgical time (OR 1.04; 95% CI 1.01-1.07; p = 0.017) and elevated D-dimer level (OR 2.79; 95% CI 1.34-4.83; p = 0.004).

CONCLUSION

These epidemiologic data may be helpful in individualized assessment, risk stratification, and development of targeted prevention programs.

From Classical Laboratory Parameters to Novel Biomarkers for the Diagnosis of Venous Thrombosis

Venous thrombosis is a common and potentially fatal disease, because of its high morbidity and mortality, especially in hospitalized patients. To establish the diagnosis of venous thrombosis, in the last years, a multi-modality approach that involves not only imaging modalities but also serology has been evolving. Multiple studies have demonstrated the use of some biomarkers, such as D-dimer, selectins, microparticles or inflammatory cytokines, for the diagnosis and treatment of venous thrombosis, but there is no single biomarker available to exclusively confirm the diagnosis of venous thrombosis. Considering the fact that there are some issues surrounding the management of patients with venous thrombosis and the duration of treatment, recent studies support the idea that these biomarkers may help guide the length of appropriate anticoagulation treatment, by identifying patients at high risk of recurrence. At the same time, biomarkers may help predict thrombus evolution, potentially identifying patients that would benefit from more aggressive therapies. This review focuses on classic and novel biomarkers currently under investigation, discussing their diagnostic performance and potential benefit in guiding the therapy for venous thrombosis.

Effects of plasma transfusions on antithrombin levels after paediatric liver transplantation

BACKGROUND AND OBJECTIVES

Thrombotic complications affect 3-10% of patients after liver transplantation (LT), leading to potentially life-threatening complications. In the days following LT, antithrombin (AT) is decreased longer than pro-coagulant factors, thus favouring a pro-thrombotic profile. Plasma transfusions are given empirically in some centres to correct AT levels following LT. We assessed the effect of plasma transfusion on AT levels after paediatric LT.

MATERIALS AND METHODS

Prospective single-centre observational study in 20 consecutive paediatric LT recipients over a 24-month period. Plasma was administered twice daily (10 ml/kg/dose) according to an existing protocol. AT levels were measured once daily, immediately prior to and one hour after the morning plasma transfusion. Sample size was calculated based on a non-inferiority hypothesis.

RESULTS

The median age and weight were 11.6 years (IQR 2.8; 14.7) and 40 kg (IQR 12.75; 44.8), respectively. We collected 85-paired blood samples. The median AT level prior to plasma transfusion was 58%. The median difference in AT levels before and after plasma transfusion was 4.2% (P = 0.001). Changes in AT levels after plasma transfusion were not correlated with baseline AT levels (R = 0.19) or patient weight (R = 0.18).

CONCLUSION

Plasma transfusions only marginally increase AT levels in children after LT. Therefore, prophylactic plasma transfusions probably do not seem to confer an advantage in the routine management of paediatric LT patients. Randomized controlled trials are needed to identify the optimal anticoagulation strategy in this specific population.

Targeting factor VIII expression to platelets for hemophilia A gene therapy does not induce an apparent thrombotic risk in mice

Essentials Platelet-Factor (F) VIII gene therapy is a promising treatment in hemophilia A. This study aims to evaluate if platelet-FVIII expression would increase the risk for thrombosis. Targeting FVIII expression to platelets does not induce or elevate thrombosis risk. Platelets expressing FVIII are neither hyper-activated nor hyper-responsive.

SUMMARY

Background Targeting factor (F) VIII expression to platelets is a promising gene therapy approach for hemophilia A, and is successful even in the presence of inhibitors. It is well known that platelets play important roles not only in hemostasis, but also in thrombosis and inflammation. Objective To evaluate whether platelet-FVIII expression might increase thrombotic risk and thereby compromise the safety of this approach. Methods In this study, platelet-FVIII-expressing transgenic mice were examined either in steady-state conditions or under prothrombotic conditions induced by inflammation or the FV Leiden mutation. Native whole blood thrombin generation assay, rotational thromboelastometry analysis and ferric chloride-induced vessel injury were used to evaluate the hemostatic properties. Various parameters associated with thrombosis risk, including D-dimer, thrombin-antithrombin complexes, fibrinogen, tissue fibrin deposition, platelet activation status and activatability, and platelet-leukocyte aggregates, were assessed. Results We generated a new line of transgenic mice that expressed 30-fold higher levels of platelet-expressed FVIII than are therapeutically required to restore hemostasis in hemophilic mice. Under both steady-state conditions and prothrombotic conditions induced by lipopolysaccharide-mediated inflammation or the FV Leiden mutation, supratherapeutic levels of platelet-expressed FVIII did not appear to be thrombogenic. Furthermore, FVIII-expressing platelets were neither hyperactivated nor hyperactivatable upon agonist activation. Conclusion We conclude that, in mice, more than 30-fold higher levels of platelet-expressed FVIII than are required for therapeutic efficacy in hemophilia A are not associated with a thrombotic predilection.

Thrombin-antithrombin III complex tests

PURPOSE

Patients with fractures of the pelvis and/or lower extremities are at a high risk of developing postoperative venous thromboembolism (VTE). The purpose of this study was to determine whether the thrombin-antithrombin III complex (TAT) tests could be used for postoperative screening of VTE in patients with lower limb or pelvic fractures.

METHODS

We enrolled 133 patients who underwent surgical treatment for fracture of the pelvis or lower extremities. TAT and D-dimer levels were compared in patients with and without VTE. Receiver operating characteristic (ROC) curve analysis was done and the appropriate TAT and D-dimer cutoff levels were determined for VTE screening.

RESULTS

VTE was diagnosed in 41 patients (30.8%). Patients with VTE had significantly higher levels of TAT and D-dimer on postoperative days 1, 3, and 7 than those without VTE, respectively. ROC curve analysis suggested that TAT test at postoperative day 7 had the highest accuracy for predicting postoperative VTE. With the optimal cutoff TAT level of 3.0 ng/mL, sensitivity and specificity were 93.3% and 70.1%, respectively. With the optimal cutoff D-dimer level of 7.4 µg/mL, sensitivity and specificity were 93.3% and 57.0%, respectively.

CONCLUSION

TAT levels measured at postoperative day 7 could be the most useful parameter for screening postoperative VTE. TAT can be used as a screening tool for screening postoperative VTE in patients with lower limb and pelvic fractures.

Deep venous thrombosis following different isolated lower extremity fractures: what is known about prevalences, locations, risk factors and prophylaxis?

INTRODUCTION

Deep venous thrombosis (DVT) offers a high risk of morbidity and mortality, especially in case of pulmonary embolism. Precise data as to DVT after isolated lower extremity fractures (ILEFs) are rare. Even organizations like the American Academy of Orthopaedic Surgeons or the American College of Chest Physicians do not state exact recommendations as to optimal DVT prophylaxis (ppx) after ILEFs.

PREVALENCE

The incidence of DVT ranges from 5 to 86 % depending on the fracture whereas femur fractures offer the highest risk for clotting. The incidence seems to decrease in more distal fractures.

LOCATION

The risk to develop proximal clots is likely low, however, especially these are feared by surgeons. DVT can occur in both the injured and uninjured leg with a trend for higher incidences in the injured leg.

RISK FACTORS

Risk factors for DVT after ILEF seem to be similar to risk factors for DVT development after orthopaedic surgery and in general. Risk factors caused by surgeons are the use of a tourniquet, prolonged operative time and a delay from injury to surgery.

PROPHYLAXIS

Low molecular weight heparin is favoured by many authors, however, warfarin and acetylsalicylic acid are also used. Clear recommendations are still missing.

CONCLUSION

The rate of morbidity caused by DVT after ILEF is poorly understood so far. Exact data on prevalences are missing and optimal DVT prophylaxis still has to be defined.

Markers of thrombin generation during resurfacing and noncemented total hip arthroplasty: a pilot study

BACKGROUND

Hip resurfacing arthroplasty (HRA) could be associated with an increased risk of deep vein thrombosis (DVT) compared to traditional noncemented THA because it involves greater dissection, increased kinking and distortion of the femoral vessels, takes longer to perform, and involves insertion of some cement into the femur.

QUESTIONS/PURPOSES

Does HRA lead to greater risk of thromboembolism compared with noncemented THA?

METHODS

We prospectively studied 20 patients receiving HRA and 20 receiving THA. All patients were younger than 67 years old and were similar in height, weight, American Society of Anesthesiologists status, and gender mix. Patients undergoing HRA were younger (mean, 50 versus 59 years), their surgery was longer (mean, 87 versus 65 minutes), and they required more crystalloid during surgery (mean, 2160 versus 1662 mL). Radial artery blood samples were taken at six events during surgery and assayed for prothrombin fragment F1 + 2 and thrombin-antithrombin III complex (TAT) using enzyme-linked immunosorbent assays.

RESULTS

We observed no differences in the intraoperative increases in F1 + 2 and TAT between the two groups and no differences in surgical events.

CONCLUSION

Based on these data, HRA and THA should have similar risk of thromboembolism as THA based on the parameters we measured.

LEVEL OF EVIDENCE

Level I, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Early changes in the haemostatic and procoagulant systems after chemotherapy for breast cancer

Venous thromboembolism (VTE) following breast cancer chemotherapy is common. Chemotherapy-induced alterations in markers of haemostasis occur during chemotherapy. It is unclear how rapidly this occurs, whether this is upregulated in patients developing VTE and whether changes predict for VTE. Markers of haemostasis, functional clotting assays and vascular endothelial growth factor were measured before chemotherapy and at 24 h, 4 days, 8 days and 3 months following commencement of chemotherapy in early and advanced breast cancer patients and in age- and sex-matched controls. Duplex ultrasound imaging was performed after 1 month or if symptomatic. Of 123 patients, 9.8% developed VTE within 3 months. Activated partial thromboplastin time (APTT), prothrombin time (PT), D-dimer, fibrinogen, platelet count, VEGF and fibrinogen were increased in cancer. Fibrinogen, D-dimer, VEGF and tissue factor were increased, at baseline, in patients subsequently developing VTE. D-dimer of less than 500 ng ml⁻¹ has a negative predictive value of 97%. Activated partial thromboplastin time, PT and thrombin–antithrombin showed significantly different trends, as early as within 24 h, in response to chemotherapy in patients subsequently developing VTE. Markers of coagulation and procoagulants are increased, before chemotherapy, in patients who subsequently develop VTE. A group of patients at minimal risk of VTE can be identified, allowing targeted thrombopropylaxis to the higher risk group.

Altered regulation of in-vivo coagulation in orthopedic patients prior to knee or hip replacement surgery

Up to 20% of patients develop venographically proven deep-vein thrombosis after elective orthopedic surgery even under the cover of heparin or low molecular weight heparin. The extent to which the chronic inflammation of osteoarthritis requiring elective orthopedic surgery alters in-vivo coagulation and whether any specific alteration influences the development of postoperative thrombosis are unknown. This study compared the concentrations of activated factor VII (FVIIa), tissue factor pathway inhibitor (TFPI), activated factor X (FXa)-TFPI, thrombin-antithrombin, and prothrombin fragment 1+2 (F1+2) in plasmas of 535 healthy individuals (ages 17-76) with those in the preoperative plasmas of 306 arthritis patients (ages 30-92) scheduled for elective knee or hip replacement surgery. C-reactive protein was also measured in the plasmas of approximately 15% of the participants. Age-adjusted concentrations of FVIIa, F1+2, and C-reactive protein were higher in patients than controls, while the concentrations of thrombin-antithrombin, TFPI and FXa-TFPI were similar. Chronic inflammation in the patients was thus associated with increased coagulation in vivo. Without compensatory increases in the concentrations of TFPI (natural inhibitor of prothrombinase), the elevated concentrations of FVIIa in the preoperative plasmas and the trauma associated with surgery may enhance the risk for developing postoperative deep-vein thrombosis.

Rationale for the use of antifactor Xa in the treatment and prevention of venous and arterial thromboembolic events

The design and synthesis of new antithrombotic agents have led to numerous recent clinical trials to investigate their efficacy and safety. Analysis of the data from these trials, especially when the results were not totally expected, has provided interesting information, allowing a better understanding of the pathophysiology of thrombosis in various clinical situations. The aim of the present manuscript is to present the hypotheses on thrombogenesis generated by some of these recent clinical trials, notably those investigating the antithrombotic efficacy of a new synthetic and selective factor Xa inhibitor, fondaparinux. The antithrombotic efficacy of fondaparinux was recently investigated in a number of trials in the prevention and treatment of venous and arterial thrombotic disorders. In each case, the concept of the clinical efficacy of a selective factor Xa inhibitor has been proven. These trials have also clarified the implication and mode of action of factor Xa in these various types of thrombotic events. In the light of these trials, we discuss the clinical efficacy of such a selective factor Xa inhibitor, and other specific points such as the apparent lack of dose-dependency of its antithrombotic effect.

Short-term effects of estrogen, tamoxifen and raloxifene on hemostasis: a randomized-controlled study and review of the literature

INTRODUCTION

Estrogen therapy (ET), tamoxifen and raloxifene are associated with a two- to three-fold increased risk of venous thrombosis (VT); however, the mechanisms by which each drug increases venous thrombosis propensity are not fully understood. The objectives of this investigation were to compare the effects of these three treatments on hemostasis in a head to head randomized placebo-controlled trial.

PATIENTS/METHODS

Ninety-four postmenopausal women were assigned to receive oral estrogen (conjugated equine estrogen [CEE] 0.625 mg, n=23), tamoxifen 20 mg (n=24), raloxifene 60 mg (n=24) or placebo (n=23) daily for 6 months. Blood samples were analyzed for procoagulant factors (prothrombin, factors VII [fVII], VIII [fVIII], IX [fIX] and XI [fXI], D-dimer and von Willebrand factor [vWf]), anticoagulant factors (antithrombin [AT], total and free protein S, protein C and activated protein C [APC] resistance) and fibrinolytic factors (thrombin activatable fibrinolysis inhibitor [TAFI] and plasminogen activator inhibitor-1 [PAI-1]), at baseline and at 6 months of treatment.

RESULTS

Estrogen increased factor VII and D-dimer, and decreased antithrombin, total and free protein S and PAI-1. Changes with tamoxifen were distinct from estrogen with increases in factors VIII, IX, vWf and free protein S, and decreases in AT, total protein S, protein C and plasminogen activator inhibitor-1. Raloxifene produced similar effects as tamoxifen, but did not increase factor IX or decrease protein C.

CONCLUSIONS

Estrogen, tamoxifen and raloxifene affected hemostasis favoring procoagulation and impairing anticoagulation. The biochemical effects of the selective estrogen receptor modulators (SERMs) were distinct from those of estrogen and differed only subtly from each other.

Hemostatic effects of third- and second-generation oral contraceptives: absence of a causal mechanism for a difference in risk of venous thromboembolism

Some observational studies have found a difference in the risk of nonfatal venous thromboembolism (VTE) with low-dose, oral contraceptives (OCs) containing desogestrel (DSG) or gestodene (GSD) and those containing levonorgestrel (LNG). However, this does not agree with current pathophysiological concepts. This review compares all 17 comparative studies on the hemostatic effects of DSG/GSD- and LNG- or norgestimate (NGM)-containing OCs, and comments on two recent cross-sectional studies on the effects of third- and second-generation OCs on activated protein C (APC) sensitivity. In the comparative studies, the only difference in hemostatic parameters between DSG/GSD- and LNG- or NGM-containing OC users was a tendency towards higher factor VII (FVII) levels with DSG/GSD OCs. Differential effects on APC sensitivity were observed with the endogenous thrombin generation potential (ETP) assay, but not with the classical APC resistance test. FVII is not a risk marker for VTE, but is affected by dietary fat, estrogens and androgens and may interfere with the ETP assay. As no differences in established VTE risk markers were observed, there is no plausible reason for a differential risk of VTE with DSG/GSD- and LNG-containing OCs. In fact, the lack of differences with regard to established risk markers of VTE gives further support to the findings of the most recent epidemiological studies, which have not found any difference in the risk of VTE between third- and second-generation OCs.

Dose-adjusted thrombosis prophylaxis in trauma surgery according to levels of D-Dimer

In 234 trauma surgery patients, thrombosis prophylaxis with Nadroparin-Calcium low-molecular-weight heparin (LMWH) was adjusted according to levels of D-Dimer. Basic prophylaxis was 2,850 IU per day. If D-Dimer concentrations rose above 2 mg/L after the fourth postoperative (p.o.) day, LMWH was administered twice a day. Color Doppler ultrasound was performed between the fifth and seventh p.o. days. Patients were divided into a high-risk (group 1: hip, femur, or knee replacement surgery, n=102) and a moderate-risk group (group 2: other surgery of the knee, tibia, fibula, or foot, n=132). Group 1 showed significantly higher D-Dimer levels than group 2 (p<0.001). Measurement of D-Dimer on days 2 and 4 p.o. showed a sensitivity of 100% and a specificity of 72.8% in identifying patients at risk (i.e., D-Dimer>2 mg/L after day 4 p.o.). The overall deep vein thrombosis (DVT) rate in group 1 was 3.9%, and the rate of proximal DVT was 1.96%. In group 2, one distal DVT (0.8%) occurred. The results show that D-Dimer is a useful marker to monitor p.o. coagulation activation and to manage LMWH prophylaxis in trauma surgery patients.

Effects on hemostatic variables of desogestrel- and gestodene-containing oral contraceptives in comparison with levonorgestrel-containing oral contraceptives: a review

In some studies third-generation oral contraceptives have been reported to be associated with a higher risk of venous thromboembolism than are second-generation oral contraceptives, whereas recent, more refined studies have not confirmed this. The reasons for the alleged differences are under discussion, and differential effects on hemostasis have been proposed. Eighteen studies comparing second- and third-generation oral contraceptives with respect to their effects on hemostasis were analyzed. Significant changes from baseline were reported for many variables with both second- and third-generation oral contraceptives without significant between-group differences. Also, in a combined analysis of nonsignificant changes, no consistent pattern of change emerged for any marker, with the exception of higher factor VII levels associated with third-generation oral contraceptives. However, factor VII is not related to venous thromboembolism risk. In addition, 1 cross-sectional study with an unvalidated assay reported a higher ratio of activated protein C sensitivity with third-generation oral contraceptives. Only 2 components of the hemostatic system (factor VII and activated protein C sensitivity ratio) emerged as potentially differentially affected by second- and third-generation oral contraceptives; the association with venous thromboembolism risk is questionable in the former case and unknown in the latter.