A review of global coagulation assays - Is there a role in thrombosis risk prediction?

Global coagulation assays detect an early prothrombotic state in children with acute lymphoblastic leukemia

BACKGROUND

Pediatric patients with acute lymphoblastic leukemia (ALL) are at highest risk of venous thromboembolism during the induction therapy (IT). These events are not predictable by conventional coagulation assays.

OBJECTIVES

To investigate the utility of global coagulation assays (GCAs) for assessing the hemostatic state in children with ALL during IT.

METHODS

We included children with ALL (n = 15) and healthy controls (n = 15). Analyses were performed at different time points during IT of the AIEOP-BFM protocols. In addition to prothrombotic biomarkers, natural anticoagulant proteins, and in vivo thrombin generation (TG) markers, ex vivo TG was measured using the gold standard calibrated automated thrombogram method, automated ST Genesia, and thrombodynamics analyzer (TD). The latter also provided measurement of fibrin clot formation.

RESULTS

Different from conventional coagulation assays and in vivo TG markers, ex vivo GCAs detected increasing prothrombotic changes during IT. Particularly, TG measured with TD as expressed by endogenous thrombin potential was already significantly elevated at days 8 to 12 (P < .01) and continued to increase during IT compared with prior to beginning treatment, indicating a very early shift toward a procoagulant state. A similar pattern was observed for the rate of fibrin clot formation (stationary rate of clot growth: P < .01 at days 8-12). Remarkably, in patients developing thrombotic complications (n = 5), both GCAs, ST Genesia and TD, showed a significantly higher endogenous thrombin potential very early (already at days 8-12, P < .05), well before clinical manifestation.

CONCLUSION

GCAs capture prothrombotic changes early during IT in ALL pediatric patients. If confirmed, this approach will allow tailoring thromboprophylaxis in children with ALL at highest risk for venous thromboembolism.

Characteristics of factor V and protein C based on results from Korean testing centers

OBJECTIVE

The global incidence of thrombosis is increasing. However, research on thrombosis in the context of Korea is scarce. We aimed to analyze the relationship between factor V and protein C test results and thrombosis in Koreans through a domestic commissioned testing institution conducting mass examinations.

METHODS

Results of factor V and protein C tests of 1386 individuals referred simultaneously to EONE Laboratories (Incheon, Republic of Korea) from January 2017 to July 2023 were analyzed retrospectively to identify the association with thrombotic disease. The tests were performed using a STAR MAX (Diagnostica Stago, Asnieres, France) automatic blood coagulation analyzer. The results were analyzed by age and sex.

RESULTS

The inspection rate increased gradually from 2017 to 2022. Women (70.0%) demonstrated a higher test rate than did men (30.0%). Young women reported high test rates; the test rate and age distribution differed by sex. Women aged between 20 and 49 years reported lower factor V and higher protein C concentrations than did men between 20 and 49 years of age.

CONCLUSIONS

The tests were more commonly performed in women than in men. Women aged between 20 and 49 years reported lower factor V concentrations and higher protein C concentrations than men between 20 and 49 years of age. This study will facilitate recognizing and preventing thrombotic diseases in women.

Overall haemostatic potential assay for prediction of outcomes in venous and arterial thrombosis and thrombo-inflammatory diseases

Thromboembolic diseases including arterial and venous thrombosis are common causes of morbidity and mortality globally. Thrombosis frequently recurs and can also complicate many inflammatory conditions through the process of 'thrombo-inflammation,' as evidenced during the COVID-19 pandemic. Current candidate biomarkers for thrombosis prediction, such as D-dimer, have poor predictive efficacy. This limits our capacity to tailor anticoagulation duration individually and may expose lower risk individuals to undue bleeding risk. Global coagulation assays, such as the Overall Haemostatic Potential (OHP) assay, that investigate fibrin generation and fibrinolysis, may provide a more accurate and functional assessment of hypercoagulability. We present a review of fibrin's critical role as a central modulator of thrombotic risk. The results of our studies demonstrating the OHP assay as a predictive biomarker in venous thromboembolism, chronic renal disease, diabetes mellitus, post-thrombotic syndrome, and COVID-19 are discussed. As a comprehensive and global measurement of fibrin generation and fibrinolytic capacity, the OHP assay may be a valuable addition to future multi-modal predictive tools in thrombosis.

Increased blood coagulation is associated with poor neurological outcome in aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Patients with aneurysmal subarachnoid hemorrhage (aSAH) have demonstrated increased blood coagulation which is thought to contribute to delayed cerebral ischemia (DCI) and to a worse outcome. Therefore, we sought to determine whether this increased blood coagulation, detectable with rotational thromboelastometry (ROTEM), was associated with DCI and neurological outcome.

METHODS

We conducted a prospective observational study of 60 consecutive adult aSAH patients. ROTEM's EXTEM and FIBTEM assays and D-dimer were analyzed at admission and post-bleed days (PBDs) 2-3, 4-5, 7-8, and 11-12. ROTEM's clot formation time (CFT) represents the stabilization of the clot, and the maximum clot firmness (MCF) the maximum clot strength. Glasgow Outcome Scale extended (GOSe) at three months determined the neurological outcome.

RESULTS

DCI incidence was 41.7%. EXTEM-CFT was significantly shorter in patients with unfavorable neurological outcome (GOSe 1-4) on PBDs 4-5 and 7-8, p < 0.05, respectively. FIBTEM-MCF was significantly higher in patients with unfavorable neurological outcomes on PBD 4-5 (p < 0.05), PBD 7-8 (p < 0.05), and PBD 11-12 (p < 0.05). EXTEM-CFT decreased, and FIBTEM-MCF rose during the study period in all patients. Patients with unfavorable neurological outcome had a higher D-dimer at all studied time points, p < 0.05. No difference was found in the ROTEM parameters or D-dimer when assessing patients with and without DCI.

CONCLUSIONS

Patients were in a state of increased blood coagulation after aSAH, with those with unfavorable neurological outcome being more coagulable than those with favorable outcome. However, increased blood coagulation was not associated with DCI.

CLINICALTRIALS

gov, NCT03985176.

The Pitfalls of Global Hemostasis Assays in Myeloproliferative Neoplasms and Future Challenges

Venous and arterial thromboembolism are major complications of myeloproliferative neoplasms (MPNs), comprising polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Global hemostasis assays, including thrombin generation assay (TGA), rotational thromboelastometry (ROTEM), and thromboelastography (TEG), have been proposed as biomarkers to assess the hypercoagulability and thrombotic risk stratification in MPNs. We performed a systematic literature review on the parameters of TGA, ROTEM, and TEG and their association with thrombotic events and treatment strategies in MPNs. Thirty-two studies (all cross-sectional) were included, which collectively enrolled 1,062 controls and 1,608 MPN patients. Among the 13 studies that reported arterial or venous thrombosis, the overall thrombosis rate was 13.8% with 6 splanchnic thromboses reported. Out of the 27 TGA studies, there was substantial heterogeneity in plasma preparation and trigger reagents employed in laboratory assays. There was a trend toward increased peak height among all MPN cohorts versus controls and higher endogenous thrombin potential (ETP) between ET patients versus controls. There was an overall trend toward lower ETP between PV and PMF patients versus. controls. There were no substantial differences in ETP between JAK2-positive versus JAK2-negative MPNs, prior history versus negative history of thrombotic events, and among different treatment strategies. Of the three ROTEM studies, there was a trend toward higher maximum clot firmness and shorter clot formation times for all MPNs versus controls. The three TEG studies had mixed results. We conclude that the ability of parameters from global hemostasis assays to predict for hypercoagulability events in MPN patients is inconsistent and inconclusive. Further prospective longitudinal studies are needed to validate these biomarker tools so that thrombotic potential could be utilized as a primary endpoint of such studies.

Comparison of the Correlation Between Coagulation Indices and Rivaroxaban Concentrations

BACKGROUND

Rivaroxaban has predictable pharmacokinetics and pharmacodynamics. However, monitoring rivaroxaban concentrations should be provided for special patients with hepatic insufficiency, high bleeding risk, and high thrombotic risk.

OBJECTIVE

This study aimed to correlate chromogenic anti-Xa assay, prothrombin time (PT), activated partial thromboplastin time (APTT), thromboelastogram reaction time (TEG R-time), and rivaroxaban concentration measured by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) (MS-Riva).

METHODS

Peripheral venous blood was collected from recruited patients 30 minutes before and 2 to 4 hours after drug administration. High-performance liquid chromatography-tandem mass spectrometry and chromogenic anti-Xa assay measured rivaroxaban concentration. Different assays were compared by Pearson correlation coefficient and Bland-Altman analysis.

RESULTS

A total of 104 patients with 191 plasma were included in the study. Overall analysis shows that chromogenic anti-Xa assay, PT, APTT, and TEG R-time strongly correlated with MS-Riva (r = 0.986; r = 0.884; r = 0.741; r = 0.739; P < 0.001). Rivaroxaban peak concentration detected by HPLC-MS/MS (MS-peak) showed a very strong correlation with the chromogenic anti-Xa assay (r = 0.977, P < 0.001) and moderate correlation with PT, APTT, and TEG R-time (r = 0.670; r = 0.571; r = 0.481, P < 0.001). Rivaroxaban trough concentration detected by HPLC-MS/MS (MS-trough) correlated strongly with the chromogenic anti-Xa assay (r = 0.884, P < 0.001), weakly with APTT (r = 0.313; P = 0.043), and not significantly with PT and TEG R-time (P = 0.140; P = 0.341).

CONCLUSION AND RELEVANCE

High-performance liquid chromatography-tandem mass spectrometry/MS is the preferred choice for monitoring peak and tough concentrations, followed by anti-Xa, while PT is only suitable for peak concentrations. This study can help the clinicians to better adjust the medication regimen and reduce the risk of recurrence of thrombosis as well as the risk of bleeding.

Global coagulation assays in patients with chronic kidney disease and their role in predicting thrombotic risk

BACKGROUND

Despite cardiovascular diseases and thrombosis being major causes of death in patients with chronic kidney disease (CKD), there remains no effective biomarker to predict thrombotic risk in this population.

OBJECTIVE

To evaluate global coagulation assays in patients with CKD and correlate the biomarkers to clinical outcomes.

MATERIAL AND METHODS

Patients with eGFR<30 mL/min/1.73m² were recruited (n = 90) in this prospective observational study. Blood samples were collected for global coagulation assays, including thromboelastography, calibrated automated thrombogram (CAT), overall hemostatic potential (OHP) and tissue factor pathway inhibitor (TFPI).

RESULTS

Following adjustment for age and gender, CKD subjects (mean age 66 years, 36 % female) had increased maximum amplitude on thromboelastography (70.1 vs 60.2 mm, p < 0.001), higher peak thrombin (233.2 vs 219.7 mm, p = 0.030) and increased OHP (16.1 vs 6.4 units, p < 0.001) compared to healthy controls (n = 153). TFPI was also increased in CKD patients (36.4 vs 14.5 ng/mL, p < 0.001). Compared to hemodialysis patients (n = 43), peritoneal-dialysis patients (n = 25) had more hypercoagulable parameters. Thirty-five CKD patients reported thrombotic complications - key predictors included dialysis, higher fibrinogen, reduced endogenous thrombin potential, elevated D-dimer and increased TFPI. Using the dialysis cohort, the predictive risk model based on the key predictors performed better than Framingham heart score and number of cardiovascular risk factors (Harrell's C-stat 0.862 vs 0.585 vs 0.565).

CONCLUSION

CKD appears to confer a hypercoagulable state compared to healthy controls. Interestingly, reduced thrombin generation and raised TFPI was paradoxically associated with increased thrombotic risks, highlighting possible complex compensatory mechanisms within the coagulation system, which may be important in predicting clinical outcomes.

Thrombosis Risk Assessment in Myeloproliferative Neoplasm-Is There a Role for Viscoelastic Testing?

Philadelphia chromosome-negative myeloproliferative neoplasms include polycythemia vera, essential thrombocythemia, and myelofibrosis. They are associated with increased thrombotic events, and the primary goal of therapy, in particular those with polycythemia vera and essential thrombocythemia, is the prevention of thrombotic complications typically with antiplatelet therapy and/or cytoreduction. While several patient-, disease-, and genomic-related factors have been identified to influence thrombotic risks, there are no routine laboratory investigations to date that are sufficiently accurate to assess the underlying procoagulant state and predict the thrombotic risks. Conventional coagulation testing only measures time to clot formation and cannot reliably predict bleeding and thrombotic risks. Global coagulation assays such as thromboelastography, thrombin, and fibrin generation may provide a more thorough assessment of hemostatic function. Thromboelastography and thromboelastometry are viscoelastic tests which measure the mechanical properties of the hemostatic process, including the global dynamics of clot formation, stabilization, and dissolution. While viscoelastic testing is gaining traction in the investigations of coagulopathies and goal-directed blood product replacement in trauma and massive transfusion settings, the role of these assays in thrombosis is less well defined. Here, we provide a review of the current evidence of the role of viscoelastic testing in myeloproliferative neoplasm, particularly in the thrombotic risk assessment.

The effect of rivaroxaban on biomarkers in blood and plasma: a review of preclinical and clinical evidence

Rivaroxaban is a direct, oral factor Xa inhibitor that is used for the prevention and treatment of various thromboembolic disorders. Several preclinical and clinical studies have utilized specific molecules as biomarkers to investigate the potential role of rivaroxaban beyond its anticoagulant activity and across a range of biological processes. The aim of this review is to summarize the existing evidence regarding the use of blood-based biomarkers to characterize the effects of rivaroxaban on coagulation and other pathways, including platelet activation, inflammation and endothelial effects. After a literature search using PubMed, almost 100 preclinical and clinical studies were identified that investigated the effects of rivaroxaban using molecular biomarkers. In agreement with the preclinical data, clinical studies reported a trend for reduction in the blood concentrations of D-dimers, thrombin-antithrombin complex and prothrombin fragment 1 + 2 following treatment with rivaroxaban in both healthy individuals and those with various chronic conditions. Preclinical and also some clinical studies have also reported a potential impact of rivaroxaban on the concentrations of platelet activation biomarkers (von Willebrand factor, P-selectin and thrombomodulin), endothelial activation biomarkers (matrix metalloproteinase-9, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) and inflammation biomarkers (interleukin-6, tumor necrosis factor-α and monocyte chemoattractant protein-1). Based on the results of biomarker studies, molecular biomarkers can be used in addition to traditional coagulation assays to increase the understanding of the anticoagulation effects of rivaroxaban. Moreover, there is preliminary evidence to suggest that rivaroxaban may have an impact on the biological pathways of platelet activation, endothelial activation and inflammation; however, owing to paucity of clinical data to investigate the trends reported in preclinical studies, further investigation is required to clarify these observations.

Thromboelastography Parameters do not Discriminate for Thrombotic Events in Hospitalized Patients With COVID-19

Background

Coronavirus disease 2019 (COVID-19) is associated with a prothrombotic state; leading to multiple sequelae. We sought to detect whether thromboelastography (TEG) parameters would be able to detect thromboembolic events in patients hospitalized with COVID-19.

Methods

We performed a retrospective multicenter case–control study of the Collaborative Research to Understand the Sequelae of Harm in COVID (CRUSH COVID) registry of 8 tertiary care level hospitals in the United States (US). This registry contains adult patients with COVID-19 hospitalized between March 2020 and September 2020.

Results

A total of 277 hospitalized COVID-19 patients were analyzed to determine whether conventional coagulation TEG parameters were associated with venous thromboembolic (VTE) and thrombotic events during hospitalization. A clotting index (CI) >3 was present in 45.8% of the population, consistent with a hypercoagulable state. Eighty-three percent of the patients had clot lysis at 30 min (LY30)  =  0, consistent with fibrinolysis shutdown, with a median of 0.1%. We did not find TEG parameters (LY30 area under the receiver operating characteristic [ROC] curve [AUC]  =  0.55, 95% CI: 0.44-0.65, P value  =  .32; alpha angle [α] AUC  =  0.58, 95% CI: 0.47-0.69, P value  =  .17; K time AUC  =  0.58, 95% CI: 0.46-0.69, P value  =  .67; maximum amplitude (MA) AUC  =  0.54, 95% CI: 0.44-0.64, P value  =  .47; reaction time [R time] AUC  =  0.53, 95% CI: 0.42-0.65, P value  =  .70) to be a good discriminator for VTE. We also did not find TEG parameters (LY30 AUC  =  0.51, 95% CI: 0.42-0.60, P value  =  .84; R time AUC  =  0.57, 95%CI: 0.48-0.67, P value .07; α AUC  =  0.59, 95%CI: 0.51-0.68, P value  =  .02; K time AUC  =  0.62, 95% CI: 0.53-0.70, P value  =  .07; MA AUC  =  0.65, 95% CI: 0.57-0.74, P value < .01) to be a good discriminator for thrombotic events.

Conclusions

In this retrospective multicenter cohort study, TEG in COVID-19 hospitalized patients may indicate a hypercoagulable state, however, its use in detecting VTE or thrombotic events is limited in this population.

Thrombin generation assays to personalize treatment in bleeding and thrombotic diseases

Treatment of bleeding and thrombotic disorders is highly standardized and based on evidence-based medicine guidelines. These evidence-based treatment schemes are well accepted but may lead to either insufficient treatment or over-dosing, because the individuals' hemostatic properties are not taken into account. This can potentially introduce bleeding or thrombotic complications in individual patients. With the incorporation of pharmacokinetic (PK) and pharmacodynamic (PK-PD) parameters, based on global assays such as thrombin generation assays (TGAs), a more personalized approach can be applied to treat either bleeding or thrombotic disorders. In this review, we will discuss the recent literature about the technical aspects of TGAs and the relation to diagnosis and management of bleeding and thrombotic disorders. In patients with bleeding disorders, such as hemophilia A or factor VII deficiency, TGAs can be used to identify patients with a more severe bleeding phenotype and also in the management with non-replacement therapy and/or bypassing therapy. These assays have also a role in patients with venous thrombo-embolism, but the usage of TGAs in patients with arterial thrombosis is less clear. However, there is a potential role for TGAs in the monitoring of (long-term) antithrombotic therapy, for example with the use of direct oral anticoagulants. Finally this review will discuss controversies, limitations and knowledge gaps in relation to the introduction of TGAs to personalize medicine in daily medical practice.

Plasma Angiotensin Converting Enzyme 2 (ACE2) Activity in Healthy Controls and Patients with Cardiovascular Risk Factors and/or Disease

Angiotensin converting enzyme 2 (ACE2) is an endogenous negative regulator of the renin-angiotensin system, a key factor in the development of cardiovascular disease (CVD). ACE2 is also used by SARS-CoV-2 for host cell entry. Given that COVID-19 is associated with hypercoagulability, it is timely to explore the potential relationship between plasma ACE2 activity and the coagulation profile. In this cross-sectional study, ACE2 activity and global coagulation assays (GCA) including thromboelastography, thrombin, and fibrin generation were measured in adult healthy controls (n = 123; mean age 41 ± 17 years; 35% male) and in patients with cardiovascular risk factors and/or disease (n = 258; mean age 65 ± 14 years; 55% male). ACE2 activity was significantly lower in controls compared to patients with cardiovascular risk factors and/or disease (median 0.10 (0.02, 3.33) vs. 5.99 (1.95, 10.37) pmol/mL/min, p < 0.001). Of the healthy controls, 48% had undetectable ACE2 activity. Controls with detectable ACE2 had lower maximum amplitude (p < 0.001). In patients with cardiovascular risk factors and/or disease, those in the 3rd tertile were older and male (p = 0.002), with a higher Framingham grade and increased number of cardiovascular risk factors (p < 0.001). In conclusion, plasma ACE2 activity is undetectable to very low in young healthy controls with minimal clinically relevant associations to GCA. Patients with cardiovascular risk factors and/or disease have increased plasma ACE2 activity, suggesting that it may be an important biomarker of endothelial dysfunction and atherosclerosis.

Risk stratification for pregnancy-associated venous thromboembolism: Potential role for global coagulation assays

Risk assessment for venous thromboembolism in pregnancy and the puerperium is currently limited to stratifying clinical surrogate risk factors without high-quality evidence. While the absolute risk of pregnancy-associated venous thromboembolism is low for the vast majority of women, associated morbidity and mortality remains significant. As guidelines for thromboprophylaxis vary widely, some women may be under- or over-anticoagulated, contributing to poor outcomes. New global coagulation assays provide a holistic view of coagulation and may have the potential to detect hypercoagulability in pregnancy, unlike clinically available coagulation assays. However, there are major technical challenges to overcome before global coagulation assays can be realistically proposed as an adjunct to risk assessment for pregnancy-associated venous thromboembolism. This review summarises the literature and controversies in the prediction and prevention of pregnancy-associated venous thromboembolism and outlines the new tools in haematology that may assist in our future understanding of hypercoagulability in pregnancy.

The Need for Individualized Risk Assessment in Cardiovascular Disease

Cardiovascular disease remains the leading cause of death in the era of modern medicine despite major advancements in this field. Current available clinical surrogate markers and blood tests do not adequately predict individual risk of cardiovascular disease. A more precise and sophisticated tool that can reliably predict the thrombosis and bleeding risks at an individual level is required in order for clinicians to confidently recommend early interventions with a favorable risk–benefit profile. Critical to the development of this tool is the assessment and understanding of Virchow’s triad and its complex interactions between hypercoagulability, endothelial dysfunction and vessel flow, a fundamental concept to the development of thrombosis. This review explores the pathophysiology of cardiovascular disease stemming from the triad of factors and how individualized risk assessment can be improved through the multimodal use of tools such as global coagulation assays, endothelial biomarkers and vessel flow assessment.

Global coagulation assays in hypercoagulable states

Thrombosis is one of the major global causes of morbidity and mortality, and predicting the risk of thrombotic and cardiovascular complications remains one of the key challenges in modern medicine. Conventional coagulation testing does not provide sufficient information, primarily because they measure the time to start of blood clotting and do not evaluate total thrombin generation. Possible adjunctive tools that may be helpful are global coagulation assays, which includes the assessment of the final products of the coagulation cascade, namely thrombin and fibrin. Whilst these assays have been more widely investigated in bleeding states, their role in thrombotic disorders is less established. We have previously investigated the use of assays such as thromboelastography, calibrated automated thrombogram and overall haemostatic potential assay in several hypercoagulable states including cardiovascular disease, haematological disorders and influence of hormone status as well as healthy controls. We provide a review of the use and limitations of global coagulation assays in healthy controls as well as hypercoagulable conditions.

Effect of remote ischemic preconditioning on fibrin formation and metabolism in patients undergoing hip fracture surgery: a randomized clinical trial

Remote ischemic preconditioning (RIPC) prior to surgery has recently been shown to reduce the risk of myocardial injury and myocardial infarction after hip fracture surgery. This study investigated whether RIPC initiated antithrombotic mechanisms in patients undergoing hip fracture surgery. This trial was a predefined sub-study of a multicentre randomized clinical trial. Adult patients with cardiovascular risk factors undergoing hip fracture surgery between September 2015 and September 2017 were randomized 1 : 1 to RIPC or control. RIPC was initiated before surgery with a tourniquet applied to the upper arm and it consisted of four cycles of 5 min of forearm ischemia followed by five minutes of reperfusion. The outcomes such as surgery-induced changes in thrombin generation, fibrinogen/fibrin turnover, tissue plasminogen activator, plasminogen activator inhibitor-1 and fibrin structure measurements were determined preoperatively (prior to RIPC) and 2 h postoperatively. One hundred and thirty-seven patients were randomized to RIPC (n = 65) or control (n = 72). There were no significant changes in thrombin generation, fibrinogen/fibrin turnover or fibrin structure measurements determined pre and postoperatively between patients in the RIPC and control groups. Subgroup analyses on patients not on anticoagulant therapy (n = 103), patients receiving warfarin (n = 17) and patients receiving direct oral anticoagulant therapy (n = 18) showed no significant changes between the RIPC-patients and controls. RIPC did not affect changes in thrombin generation, fibrin turnover or fibrin structure in adult patients undergoing hip fracture surgery suggesting that the cardiovascular effect of RIPC in hip fracture surgery is not related to alterations in fibrinogen/fibrin metabolism.

Clinical use of thrombin generation assays

Determining patient's coagulation profile, i.e. detecting a bleeding tendency or the opposite, a thrombotic risk, is crucial for clinicians in many situations. Routine coagulation assays and even more specialized tests may not allow a relevant characterization of the hemostatic balance. In contrast, thrombin generation assay (TGA) is a global assay allowing the dynamic continuous and simultaneous recording of the combined effects of both thrombin generation and thrombin inactivation. TGA thus reflects the result of procoagulant and anticoagulant activities in blood and plasma. Because of this unique feature, TGA has been widely used in a wide array of settings from both research, clinical and pharmaceutical perspectives. This includes diagnosis, prognosis, prophylaxis, and treatment of inherited and acquired bleeding and thrombotic disorders. In addition, TGA has been shown to provide relevant information for the diagnosis of coagulopathies induced by infectious diseases, comprising also disturbance of the coagulation system in COVID-19, or for the assessment of early recurrence in breast cancer. This review article aims to document most clinical applications of TGA.

Global coagulation assays in patients with diabetes mellitus

BACKGROUND

There is significant heterogeneity in the incidence and severity of diabetes-associated vascular complications and there is no routine biomarker that accurately predicts these outcomes. This pilot study investigates the role of global coagulation assays in patients with diabetes mellitus.

METHODS

In this cross-sectional study, patients with diabetes not on anticoagulation or dialysis and without active malignancy were recruited from endocrinology clinics. Blood samples were collected for global coagulation assays including thromboelastography (TEG), thrombin generation using calibrated automated thrombogram (CAT), and fibrin generation and fibrinolysis using the overall hemostatic potential (OHP) assay. The results were compared with healthy controls.

RESULTS

A total of 147 adult patients including 19 with type 1 diabetes (T1DM), 120 with type 2 diabetes (T2DM), and eight with latent autoimmune diabetes were recruited. Compared with 153 healthy controls, patients with diabetes demonstrated higher maximum amplitude (68.6 vs 60.2 mm, p < 0.001) on TEG, and higher OHP (9.3 vs 6.4, p < 0.001) with comparable CAT parameters. Patients with T2DM were more hypercoagulable than those with T1DM on most biomarkers. Higher maximum amplitude, velocity index, and OHP were associated with increased risk of complications (C-stat 0.82). Patients with history of microvascular complications appear to have more hypercoagulable thrombin and fibrin generation than those without.

CONCLUSION

Patients with diabetes have more hypercoagulable profiles on global coagulation assays, particularly patients with T2DM and those with microvascular complications. Further studies with longitudinal follow-up are ongoing to evaluate the utility of global coagulation assays in predicting long-term patient outcomes.

Thrombin generation in children using ThromboScreen reagent kit with ST Genesia-A pilot study

INTRODUCTION

Thrombin generation assays assess overall coagulation system and are widely used in research; however, they still need standardization and clinical validation. The new ST Genesia is a benchtop, automated analyzer that normalizes each thrombin generation parameter using a reference plasma. The ThromboScreen reagent kit has two triggers, one of which contains thrombomodulin to assess the effect of the protein C pathway. This study aimed to make a pilot approach to the ThromboScreen reference range in children and evaluate the impact of sex, age, and pro- and anticoagulant plasma proteins on thrombin generation parameters.

METHODS

This study included 55 healthy children from the following age groups: 1-6 years (n = 14), 7-11 years (n = 15), and 12-17 years (n = 26). Children younger than 1 year were excluded from the study. We measured thrombin generation using ThromboScreen, coagulation routine and test, pro- and anticoagulant proteins.

RESULTS

Age did not influence ThromboScreen results. Males showed significantly lower endogenous thrombin potential and peak height values than females. The strongest determinants of endogenous thrombin potential were von Willebrand factor parameters, whereas for endogenous thrombin potential inhibition, the strongest determinants were protein C and protein S. No statistically significant differences were found between groups on temporal parameters.

CONCLUSIONS

For the ThromboScreen reagent kit, it may not be necessary to subdivide reference ranges according to age for children (>1 year).

Pulmonary arterial hypertension patients display normal kinetics of clot formation using thrombelastography

Pulmonary arterial hypertension is characterized by endothelial dysfunction and microthrombi formation. The role of anticoagulation remains controversial, with studies demonstrating inconsistent effects on pulmonary arterial hypertension mortality. Clinical anticoagulation practices are currently heterogeneous, reflecting physician preference. This study uses thrombelastography and hematology markers to evaluate whether clot formation and fibrinolysis are abnormal in pulmonary arterial hypertension patients. Venous blood was collected from healthy volunteers (n = 20) and patients with pulmonary arterial hypertension (n = 20) on stable medical therapy for thrombelastography analysis. Individual thrombelastography parameters and a calculated coagulation index were used for comparison. In addition, hematologic markers, including fibrinogen, factor VIII activity, von Willebrand factor activity, von Willebrand factor antigen, and alpha2-antiplasmin, were measured in pulmonary arterial hypertension patients and compared to healthy volunteers. Between group differences were analyzed using t tests and linear mixed models, accounting for repeated measures when applicable. Although the degree of fibrinolysis (LY30) was significantly lower in pulmonary arterial hypertension patients compared to healthy volunteers (0.3% ± 0.6 versus 1.3% ± 1.1, p = 0.04), all values were within the normal reference range (0–8%). All other thrombelastography parameters were not significantly different between pulmonary arterial hypertension patients and healthy volunteers (p ≥ 0.15 for all). Similarly, alpha2-antiplasmin activity levels were higher in pulmonary arterial hypertension patients compared to healthy volunteers (103.7% ± 13.6 versus 82.6% ± 9.5, p < 0.0001), but all individual values were within the normal range (75–132%). There were no other significant differences in hematologic markers between pulmonary arterial hypertension patients and healthy volunteers (p ≥ 0.07 for all). Sub-group analysis comparing thrombelastography results in patients treated with or without prostacyclin pathway targeted therapies were also non-significant. In conclusion, treated pulmonary arterial hypertension patients do not demonstrate abnormal clotting kinetics or fibrinolysis by thrombelastography.

Thromboelastography and rotational thromboelastometry in bleeding patients with coagulopathy: Practice management guideline from the Eastern Association for the Surgery of Trauma

BACKGROUND

Assessment of the immediate need for specific blood product transfusions in acutely bleeding patients is challenging. Clinical assessment and commonly used coagulation tests are inaccurate and time-consuming. The goal of this practice management guideline was to evaluate the role of the viscoelasticity tests, which are thromboelastography (TEG) and rotational thromboelastometry (ROTEM), in the management of acutely bleeding trauma, surgical, and critically ill patients.

METHODS

Systematic review and meta-analyses of manuscripts comparing TEG/ROTEM with non-TEG/ROTEM-guided blood products transfusions strategies were performed. The Grading of Recommendations Assessment, Development and Evaluation methodology was applied to assess the level of evidence and create recommendations for TEG/ROTEM-guided blood product transfusions in adult trauma, surgical, and critically ill patients.

RESULTS

Using TEG/ROTEM-guided blood transfusions in acutely bleeding trauma, surgical, and critically ill patients was associated with a tendency to fewer blood product transfusions in all populations. Thromboelastography/ROTEM-guided transfusions were associated with a reduced number of additional invasive hemostatic interventions (angioembolic, endoscopic, or surgical) in surgical patients. Thromboelastography/ROTEM-guided transfusions were associated with a reduction in mortality in trauma patients.

CONCLUSION

In patients with ongoing hemorrhage and concern for coagulopathy, we conditionally recommend using TEG/ROTEM-guided transfusions, compared with traditional coagulation parameters, to guide blood component transfusions in each of the following three groups: adult trauma patients, adult surgical patients, and adult patients with critical illness.

LEVEL OF EVIDENCE

Systematic Review/Meta-Analysis, level III.

Global coagulation assays in healthy controls: are there compensatory mechanisms within the coagulation system?

Global coagulation assays (GCAs) may provide a more comprehensive individual hemostatic profiling. We aim to evaluate GCAs (thromboelastography, thrombin generation) in healthy controls, and correlate results with age, gender, lipid status, tissue factor pathway inhibitor (TFPI) and P-selectin. Blood samples were collected from healthy controls (> 18 years of age) not taking anticoagulation or antiplatelet agents and without known cardiovascular disease. Thromboelastography (TEG) was performed on citrated whole blood while calibrated automated thrombogram (CAT), P-selectin (endothelial marker) and TFPI (principle inhibitor of tissue factor-initiated coagulation) were performed on platelet-poor plasma. 153 healthy controls (mean age 42 years, 98 females (64%)) were recruited. Female controls demonstrated more hypercoagulable TEG and CAT parameters while those over 50 years of age demonstrated more hypercoagulable TEG parameters despite comparable thrombin generation. Paradoxically, individuals with "flattened" thrombin curves (lower velocity index (rate of thrombin generation) despite preserved endogenous thrombin potential (amount of thrombin)) were more likely to be male (49% vs 20%, p = 0.003) with increased low-density lipoprotein cholesterol (3.3 vs 2.6 mmol/L, p = 0.003), P-selectin (54.2 vs 47.3 ng/mL, p = 0.038) and TFPI (18.7 vs 8.6 ng/ml, p = 0.001). In addition to reduced velocity index and thrombin peak, controls in the highest TFPI tertile also demonstrated a poorer lipid profile. GCAs can detect subtle changes of the hemostatic profile. Interestingly, reduced thrombin generation was paradoxically associated with increased cardiovascular risk factors, possibly attributable to increased TFPI. This finding may suggest compensation by the coagulation system in response to endothelial activation and represent a biomarker for early cardiovascular disease. A larger prospective study evaluating these assays in the cardiovascular disease population is ongoing.

Individualised Risk Assessments for Recurrent Venous Thromboembolism: New Frontiers in the Era of Direct Oral Anticoagulants

Venous thromboembolism (VTE) is a leading cause of morbidity and mortality and is associated with high recurrence rates. The introduction of direct oral anticoagulants (DOACs) in the 2010s has changed the landscape of VTE management. DOACs have become the preferred anticoagulant therapy for their ease of use, predictable pharmacokinetics, and improved safety profile. Increasingly, guidelines have recommended long term anticoagulation for some indications such as following first unprovoked major VTE, although an objective individualised risk assessment for VTE recurrence remains elusive. The balance of preventing VTE recurrence needs to be weighed against the not insignificant bleeding risk, which is cumulative with prolonged use. Hence, there is a need for an individualised, targeted approach for assessing the risk of VTE recurrence, especially in those patients in whom the balance between benefit and risk of long-term anticoagulation is not clear. Clinical factors alone do not provide the level of discrimination required on an individual level. Laboratory data from global coagulation assays and biomarkers may provide enhanced risk assessment ability and are an active area of research. A review of the prediction models and biomarkers for assessing VTE recurrence risk is provided, with an emphasis on contemporary developments in the era of DOACs and global coagulation assays.

Study of thrombin generation with St Genesia to evaluate xaban pharmacodynamics: Analytical performances over 18 months

INTRODUCTION

ST Genesia is a new automated system enabling quantitative standardized evaluation of thrombin generation (TG), for example, in patients receiving anti-Xa direct inhibitors (xabans). Data on its analytical performances are scarce.

METHODS

Over an 18-month period, repeatability, reproducibility, and accuracy were assessed using STG-ThromboScreen (without or with thrombomodulin) or STG-DrugScreen reagents (corresponding to intermediate/high tissue-factor concentration, respectively), and controls. Furthermore, reproducibility was assessed using commercialized lyophilized and frozen normal pooled plasmas. Rivaroxaban and apixaban impacts on TG parameters were assessed using spiking experiments. Finally, a comparison with the Calibrated Automated Thrombogram method (CAT) (PPP reagent) was performed using plasma from healthy volunteers enrolled in the DRIVING-studyNCT01627665) before and after rivaroxaban intake.

RESULTS

For all dedicated quality control (QC) levels, inter-series coefficients of variations (CV) were <7% for temporal TG parameters, peak height (PH), and endogenous thrombin potential (ETP), whether results were normalized with a dedicated reference plasma STG-RefPlasma or not. Noteworthy, STG-RefPlasma used for normalization displayed substantially high PH and ETP. Mean biases between the observed and manufacturer's assigned QC values were mostly <7%. Both rivaroxaban/apixaban plasma concentrations were significantly associated with TG parameters. Finally, Bland-Altman plots showed a good agreement between ST Genesia-STG-ThromboScreen and CAT method within the explored range of values, although biases could be observed (PH: 16.4 ± 13.2%, ETP: 17.8 ± 11.9%).

CONCLUSION

ST Genesia^® enables the reliable measurement of TG parameters in both in vitro and ex vivo xaban plasma samples using either STG-ThromboScreen or STG-DrugScreen according to xaban concentrations. The use of reference plasma, despite not completely reflecting a normal pooled plasma behavior, likely improves standardization and inter-laboratory comparisons.

Assessing maternal clotting function with novel global coagulation assays: A prospective pilot study

INTRODUCTION

Women are at higher risk of venous thromboembolism (VTE) during pregnancy and the puerperium. Global coagulation assays (GCAs), including thromboelastography (TEG), thrombin generation using the calibrated automated thrombogram (CAT) and fibrin generation using the overall haemostatic potential assay (OHP), provide a more comprehensive assessment of the coagulation process than conventional coagulation assays. We aimed to evaluate the ability of these GCAs to analyse the coagulability among pregnant women of varying VTE risk profile.

METHODS

Women undergoing term elective caesarean delivery provided a single predelivery blood sample for conventional and novel coagulation testing (TEG, CAT and OHP). Data from 47 healthy nonpregnant women aged 18-45 years were used as controls.

RESULTS

Sixty women with term singleton pregnancies were included. Samples from pregnant women were hypercoagulable on most GCA parameters compared to nonpregnant controls, demonstrating increased maximum amplitude (clot strength) (71.5 vs 60.6 mm, P < .001) on whole blood TEG and increased endogenous thrombin potential (1895.22 vs 1399.33 nmol/L·min, P < .001) and overall coagulation potential (fibrin generation) (57.58 vs 36.21 units, P < .001) on platelet-poor plasma. Pregnant women with booking BMI ≥ 30 kg/m² had significantly higher maximum amplitude compared to pregnant women of normal BMI (18.5-25 kg/m² ) (73.2 vs 66.1 mm, P < .001).

CONCLUSIONS

Global coagulation assays reliably detect the physiological hypercoagulability of pregnancy. Thromboelastography in particular appears to correlate with obesity in the pregnant population. GCAs may be potential adjuncts to risk factor-based criteria to guide VTE thromboprophylaxis during pregnancy and the puerperium.

Thromboelastography Profiles of Critically Ill Patients With Coronavirus Disease 2019

OBJECTIVES

The rate of thromboembolic events among patients with coronavirus disease 2019 is high; however, there is no robust method to identify those at greatest risk. We reviewed thromboelastography studies in critically ill patients with coronavirus disease 2019 to characterize their coagulation states.

DESIGN

Retrospective.

SETTING

Tertiary ICU in New York City.

PATIENTS

Sixty-four patients with coronavirus disease 2019 admitted to the ICU with thromboelastography performed.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Fifty percent of patients had a clotting index in the hypercoagulable range (clotting index > 3) (median 3.05). Reaction time and K values were below the lower limit of normal in 43.8% of the population consistent with a hypercoagulable profile. The median α angle and maximum amplitude (75.8° and 72.8 mm, respectively) were in the hypercoagulable range. The α angle was above reference range in 70.3% of patients indicative of rapid clot formation. Maximum amplitude, a factor of fibrinogen and platelet count and function, and a measure of clot strength was above reference range in 60.1% of patients. Thirty-one percent had thromboembolic events; thromboelastography parameters did not correlate with events in our cohort. Those with D-dimer values greater than 2,000 were more likely to have shorter reaction times compared with those with D-dimer levels less than or equal to 2,000 (4.8 vs 5.6 min; p = 0.001).

CONCLUSIONS

A large proportion of critically ill patients with coronavirus disease 2019 have hypercoagulable thromboelastography profiles with additional derangements related to fibrinogen and platelet function. As the majority of patients have an elevated thromboelastography maximum amplitude, a follow-up study evaluating platelet aggregation would be instructive.

Diagnostic Accuracy in Acute Venous Thromboembolism: Comparing D-Dimer, Thrombin Generation, Overall Hemostatic Potential, and Fibrin Monomers

Introduction  For acute venous thromboembolism (VTE), a biomarker with higher specificity than D-dimer would be of great clinical use. Thrombin generation and overall hemostatic potential (OHP) reflect the hemostatic balance by globally assessing multiple coagulation factors and inhibitors. These tests discriminate between healthy controls and patients with a prothrombotic tendency but have yet to be established as clinical biomarkers of VTE.

Objective  This study compares endogenous thrombin potential (ETP) and OHP to D-dimer and fibrin monomers (FM) in outpatients with suspected VTE.

Methods  A cross-sectional diagnostic study where 954 patients with suspected pulmonary embolism or deep venous thrombosis were recruited consecutively from the medical emergency department at Karolinska University Hospital. D-dimer, FM, OHP, and ETP were analyzed in a subpopulation of 60 patients with VTE and 98 matched controls without VTE. VTE was verified either by ultrasonography or computed tomography and clinical data were collected from medical records.

Results  Compared with healthy controls, both VTE and non-VTE patients displayed prothrombotic profiles in OHP and ETP. D-dimer, FM, ETP area under the curve (AUC), and ETP T _lag were significantly different between patients with VTE and non-VTE. The largest receiver-operating characteristic AUCs for discrimination between VTE and non-VTE, were found in D-dimer with 0.94, FM 0.77, and ETP AUC 0.65. No useful cutoff could be identified for the ETP or the OHP assay.

Conclusion  Compared with D-dimer, neither ETP nor OHP were clinically viable biomarkers of acute venous thrombosis. The data indicated that a large portion of the emergency patients with suspected VTE were in a prothrombotic state.

A critical review on the occurrence of resistomes in the environment and their removal from wastewater using apposite treatment technologies: Limitations, successes and future improvement

Recent reports are pointing towards the potential increasing risks of resistomes in human host. With no permissible limit in sight, resistomes are continually multiplying at an alarming rate in the ecosystem, with a disturbing level in drinking water source. The morphology and chemical constituent of resistomes afford them to resist degradation, elude membrane and counter ionic charge, thereby, rendering both conventional and advanced water and wastewater treatment inefficient. Water and wastewater matrix may govern the propagation of individual resistomes sub-type, co-selection and specific interaction towards precise condition may have enhanced the current challenge. This review covers recent reports (2011-2019) on the occurrence of ARB/ARGs and ease of spread of resistance genes in the aquatic ecosystem. The contributions of water matrix to the spread and mitigation, treatment options, via bulk removal or capture, and intracellular and extracellular DNA lysis were discussed. A complete summary of recent occurrences of ARB/ARGs, fate after disinfection and optimum conditions of individual treatment technology or in tandem, including process limitations, with a brief assessment of removal or degradation mechanism were highlighted.

Global Coagulation Assays in Transgender Women on Oral and Transdermal Estradiol Therapy

CONTEXT

The thrombotic effects of estradiol therapy in transgender women are unclear. Global coagulation assays (GCA) may be better measures of hemostatic function compared with standard coagulation tests.

OBJECTIVE

To assess the GCA profiles of transgender women in comparison to cisgender controls and to compare how GCA differ between routes of estradiol therapy in transgender women.

DESIGN

Cross-sectional case-control study.

SETTING

General community.

PARTICIPANTS

Transgender women, cisgender male and cisgender female controls.

MAIN OUTCOME MEASURES

Citrated blood samples were analyzed for (i) whole blood thromboelastography (TEG®5000), (ii) platelet-poor plasma thrombin generation (calibrated automated thrombogram); and (iii) platelet-poor plasma fibrin generation (overall hemostatic potential assay). Mean difference (95% confidence intervals) between groups are presented.

RESULTS

Twenty-six transgender women (16 oral estradiol, 10 transdermal estradiol) were compared with 98 cisgender women and 55 cisgender men. There were no differences in serum estradiol concentration (P = 0.929) and duration of therapy (P = 0.496) between formulations. Transgender women demonstrated hypercoagulable parameters on both thromboelastography (maximum amplitude + 6.94 mm (3.55, 10.33); P < 0.001) and thrombin generation (endogenous thrombin potential + 192.62 nM.min (38.33, 326.91); P = 0.009; peak thrombin + 38.10 nM (2.27, 73.94); P = 0.034) but had increased overall fibrinolytic potential (+4.89% (0.52, 9.25); P = 0.024) compared with cisgender men. No significant changes were observed relative to cisgender women. Route of estradiol delivery or duration of use did not influence the GCA parameters.

CONCLUSION

Transgender women on estradiol therapy demonstrated hypercoagulable GCA parameters compared with cisgender men with a shift towards cisgender female parameters. Route of estradiol delivery did not influence the GCA parameters.

Thrombin generation in a woman with heterozygous factor V Leiden and combined oral contraceptives: A case report

Combined oral contraceptives and factor V Leiden mutation are multiplicative risk factors for venous thromboembolism. However, it remains unknown whether this multiplicative effect is reflected in thrombin generation assays. We report here the evolution of the thrombin generation profile while taking combined oral contraceptives and after their discontinuation in a woman with heterozygous factor V Leiden mutation. The proband exhibited a distinctly prothrombotic thrombin generation profile including markedly decreased thrombomodulin (TM) sensitivity, compared to the control population. This profile possibly reflected a high thrombotic risk. After discontinuation of combined oral contraceptives, thrombin generation and TM sensitivity improved greatly, leaving only a slightly prothrombotic profile. Therefore, the multiplied thrombotic risk occurring with simultaneous combined oral contraceptives and factor V Leiden mutation is reflected by a thrombin generation assay performed without and with TM. This could be a promising tool to identify women taking combined oral contraceptives at high risk for venous thromboembolism. Further studies are needed to verify this hypothesis.

[Platelets, hemostasis and mental disorders]

Platelets are an easily accessible model for the study of biochemical mechanisms of mental diseases, including schizophrenia and depression. This literature review addresses a role of platelet activation in the pathogenesis of mental diseases. Platelet activation observed in patients with schizophrenia, depression and other mental illnesses is associated with the development of cardiovascular disease and an increased risk of thrombotic complications, which can be the main cause of morbidity and mortality in patients with mental disorders. A deeper understanding of the biochemical mechanisms of mental disorders will help in the study of clinical consequences of these disorders and in choosing the right therapeutic strategy for patients.