Direct Oral Anticoagulants Form Thrombus Different From Warfarin in a Microchip Flow Chamber System

The Utility of Total Thrombus-Formation Analysis System (T-TAS) in the Thrombosis and Hemostasis Field: A Scoping Review

BACKGROUND

A wide variety of laboratory hemostasis tests is available, but the majority is plasma-based, static and unable to assess platelet function and fibrin formation simultaneously. The Total Thrombus-Formation Analysis System (T-TAS) is a microchip-based flow chamber system that simulates in vivo conditions for evaluating whole blood thrombogenicity.

AIM

A comprehensive overview of its applicability in different thrombosis and hemostasis related clinical situations is lacking and therefore this scoping review was performed.

MATERIALS & METHODS

A literature search was done using the electronic databases PubMed, Scopus and Embase on January 7, 2024. Original studies assessing the usefulness of the T-TAS in thrombosis and hemostasis related clinical situations were eligible for this scoping review.

RESULTS

A total of 28 studies were included; six studies investigating the role of the T-TAS in congenital bleeding disorders, five studies using the T-TAS to assess 1-year bleeding risk in patients on antiplatelet or anticoagulant medications, four studies investigating the effects of thrombocytopenia and hemodialysis on thrombus formation as measured by the T-TAS, 11 studies testing the applicability of the T-TAS in the monitoring of anticoagulant and antiplatelet therapies and eventually two studies on the ability of the T-TAS to assess the thrombogenicity in different disease entities.

DISCUSSION & CONCLUSION

The T-TAS method is an interesting technology that mimics the complex biological coagulation process using shear forces, creating a "blood vessel component on a chip". More research is needed, but it could eventually function as a screening test for platelet function and coagulation. Moreover, it could be used to detect the presence of anticoagulant and/or antiplatelet medication.

PECAM-1/Thrombus Ratio Correlates with Blood Loss during Off-Pump Coronary Artery Bypass Grafting (OPCAB) Surgery: A Preliminary Study

Platelet endothelial cell adhesion molecule 1 (PECAM-1) is considered an antiplatelet molecule. Previously, we introduced a new parameter called the PECAM-1/thrombus ratio, which indicates the proportion of PECAM-1 in the thrombus and provides a precise description of human platelet activity (in vitro). The aim of this study was to determine whether the PECAM-1/thrombus ratio could serve as a predictive factor for bleeding events during off-pump coronary artery bypass grafting (OPCAB). To achieve this, we collected blood samples from 20 patients scheduled to undergo OPCAB surgery. We assessed the PECAM-1/thrombus ratio by evaluating thrombus formation on collagen fibers under flow conditions. Subsequently, we compared the ability of the PECAM-1/thrombus ratio in predicting bleeding risk with other methods that evaluate hemostasis activity. These methods included assessing platelet P-selectin secretion, platelet exposure of phosphatidylserine, plasma coagulation and fibrinolysis system activity, and thrombus formation using the T-TAS assay. Our findings revealed a positive correlation between the PECAM-1/thrombus ratio and the amount of blood component units transfused (BCUT) during the OPCAB surgery. Furthermore, BCUT did not show any significant correlation with other measured hemostasis parameters. This preliminary study suggests that the PECAM-1/thrombus ratio might be a good predictor of bleeding risk during the OPCAB procedure.

Utility of the Total Thrombus-Formation Analysis System as a Tool for Evaluating Thrombogenicity and Monitoring Antithrombotic Therapy in Pediatric Fontan Patients

BACKGROUND

There is no consensus regarding thromboprophylaxis after Fontan procedure, and novel tools to assess thrombogenicity are needed to establish optimal thromboprophylaxis. The Total Thrombus-formation Analysis System (T-TAS) was developed for the quantitative analysis of thrombus formation using microchips with thrombogenic surfaces. This prospective study evaluated the utility of T-TAS in the assessment of thrombogenicity in pediatric Fontan patients.

METHODS AND RESULTS

The participants included 20 consecutive Fontan patients who underwent cardiac catheterization and 30 healthy controls. Blood samples collected without and with antithrombotic therapy (aspirin or aspirin and warfarin) were used for T-TAS to compute the area under the curve (AUC) in the atheroma (AR₁₀-AUC₃₀) and platelet (PL₁₈-AUC₁₀) chips. A higher AUC indicates higher thrombogenicity. T-TAS values showed that patients in the Fontan group without antithrombotic therapy had lower thrombogenicity than those in the control group [PL₁₈-AUC₁₀, median (interquartile range) 356 (313-394) vs. 408 (392-424); AR₁₀-AUC₃₀, median (interquartile range) 1270 (1178-1351) vs. 1382 (1338-1421)]. Aspirin and warfarin therapies significantly decreased PL₁₈-AUC₁₀ and AR₁₀-AUC₃₀, respectively, compared with those of patients without antithrombotic therapy (P < 0.001 for each comparison). Subgroup analysis divided by low (< 9 mmHg) or high (≥ 9 mmHg) central venous pressure (CVP) showed that CVP affects the reduction in AR₁₀-AUC₃₀ with antithrombotic therapy.

CONCLUSIONS

T-TAS may be a useful tool for monitoring thrombogenicity and antithrombotic therapy in Fontan patients.

Malnutrition-associated high bleeding risk with low thrombogenicity in patients undergoing percutaneous coronary intervention

BACKGROUND AND AIMS

Although antithrombotic treatments are established for coronary artery disease (CAD), they increase the bleeding risk, especially in malnourished patients. The total thrombus-formation analysis system (T-TAS) is useful for the assessment of thrombogenicity in CAD patients. Here, we examined the relationships among malnutrition, thrombogenicity and 1-year bleeding events in patients undergoing percutaneous coronary intervention (PCI).

METHODS AND RESULTS

This was a retrospective analysis of 300 consecutive CAD patients undergoing PCI. Blood samples obtained on the day of PCI were used in the T-TAS to compute the thrombus formation area under the curve. We assigned patients to two groups based on the geriatric nutritional risk index (GNRI): 102 patients to the lower GNRI group (≤98), 198 patients to the higher GNRI group (98<). The primary endpoint was the incidence of 1-year bleeding events defined by Bleeding Academic Research Consortium criteria types 2, 3, or 5. The T-TAS levels were lower in the lower GNRI group than in the higher GNRI group. Kaplan-Meier analysis showed worse 1-year bleeding event-free survival in the lower GNRI group compared with the higher GNRI group. The combined model of the GNRI and the Academic Research Consortium for High Bleeding Risk (ARC-HBR) had good calibration and discrimination for bleeding risk prediction. In addition, having a lower GNRI and ARC-HBR positivity was associated with 1-year bleeding events.

CONCLUSION

A lower GNRI could reflect low thrombogenicity evaluated by the T-TAS and determine bleeding risk in combination with ARC-HBR positivity.

Increased thrombogenicity is associated with revascularization outcomes in patients with chronic limb-threatening ischemia

OBJECTIVES

Clinically driven target lesion revascularization (CD-TLR) frequently occurs after endovascular therapy (EVT) in patients with chronic limb-threatening ischemia (CLTI). The total thrombus-formation analysis system (T-TAS) can quantitatively evaluate thrombogenicity. Therefore, we aimed to elucidate the association of T-TAS parameters with CD-TLR.

METHODS

We analyzed 34 CLTI patients and 62 Non-CLTI patients who underwent EVT. Blood samples collected on the day of EVT were used in T-TAS to compute the thrombus formation area under the curve (PL₂₄-AUC₁₀ in the platelet chip and AR₁₀-AUC₃₀ in the atheroma chip). After the EVT procedure, clinical follow-up was performed, and the presence of CD-TLR was assessed.

RESULTS

During the follow-up period (median 574 days), 10 patients (29%) in the CLTI group and 11 patients (18%) in the Non-CLTI group showed CD-TLR. In the CLTI group, patients who showed CD-TLR had a higher AR₁₀-AUC₃₀ than those who did not (1694 [1657, 1799] vs. 1561 [1412, 1697], p=0.01). In contrast, the PL₂₄-AUC₁₀ showed no significant differences depending on CD-TLR in both groups. For the CLTI patients, multivariable Cox regression analysis using propensity scores revealed that the AR₁₀-AUC₃₀ was an independent predictor of CD-TLR even after adjusting for baseline demographics, lesion characteristics, and anticoagulant use (HR=2.04, 95%CI=1.18-3.88, p=0.01; per 100 increase). In contrast, in Non-CLTI patients, neither the AR₁₀-AUC₃₀ and nor the PL₂₄-AUC₁₀ was significantly associated with CD-TLR. Receiver operating characteristics curve analysis identified an AR₁₀-AUC₃₀ level of 1646 as an optimal cutoff value to predict CD-TLR (AUC = 0.85, sensitivity = 0.93, specificity = 0.56).

CONCLUSIONS

In CLTI patients, but not in Non-CLTI patients, the AR₁₀-AUC₃₀ showed a potential to predict CD-TLR. This finding suggests that hypercoagulability may play a predominant role in the progression of CLTI and anticoagulants may be useful in preventing revascularization.

The Use of Total Thrombus Formation Analysis System as a Tool to Assess Platelet Function in Bleeding and Thrombosis Risk-A Systematic Review

BACKGROUND

Today there are many devices that can be used to study blood clotting disorders by identifying abnormalities in blood platelets. The Total Thrombus Formation Analysis System is an automated microchip flow chamber system that is used for the quantitative analysis of clot formation under blood flow conditions. For several years, researchers have been using a tool to analyse various clinical situations of patients to identify the properties and biochemical processes occurring within platelets and their microenvironment.

METHODS

An investigation of recent published literature was conducted based on PRISMA. This review includes 52 science papers directly related to the use of the Total Clot Formation Analysis System in relation to bleeding, surgery, platelet function assessment, anticoagulation monitoring, von Willebrand factor and others.

CONCLUSION

Most available studies indicate that The Total Thrombus Formation Analysis System may be useful in diagnostic issues, with devices used to monitor therapy or as a significant tool for predicting bleeding events. However, T-TAS not that has the potential for diagnostic indications, but allows the direct observation of the flow and the interactions between blood cells, including the intensity and dynamics of clot formation. The device is expected to be of significant value for basic research to observe the interactions and changes within platelets and their microenvironment.

Hemodialysis-related low thrombogenicity measured by total thrombus-formation analysis system in patients undergoing percutaneous coronary intervention

BACKGROUND

Established antithrombotic therapies can increase bleeding risk, especially in hemodialysis (HD) patients. The Total Thrombus-formation Analysis System (T-TAS) is useful for evaluating thrombogenicity. The aim of this study was to examine the relationship between HD and thrombogenicity, or bleeding events in patients undergoing percutaneous coronary intervention (PCI).

METHODS

In this retrospective cohort study, 300 patients undergoing elective PCI were enrolled between April 2017 and March 2019. Blood samples obtained on the day of PCI were analyzed with T-TAS to compute the thrombus formation area under the curve (AUC; PL₁₈-AUC₁₀ for platelet chip; AR₁₀-AUC₃₀ for atheroma chip). The patients were divided into three groups according to estimated glomerular filtration rate (eGFR): 33 HD patients, 124 non-HD patients with eGFR <60 mL/min/1.73m², and 143 non-HD patients with eGFR ≥60. We examined the thrombogenicity and spontaneous bleeding events within 1-year post-PCI.

RESULTS

HD was significantly associated with both low PL₁₈-AUC₁₀ and AR₁₀-AUC₃₀ levels determined by T-TAS. Bleeding events defined by the Bleeding Academic Research Consortium criteria types 2, 3, or 5 occurred during follow-up in 27 patients (9.0%): 7 in HD, 10 in non-HD with eGFR <60, and 10 in non-HD with eGFR ≥60. Both T-TAS parameters in the patients with bleeding were lower compared with those in the patients without bleeding, and HD was significantly associated with 1-year bleeding events.

CONCLUSIONS

The results suggested that HD patients undergoing PCI might be a predictor for low thrombogenicity measured by T-TAS and 1-year bleeding risk.

Development and assessment of total thrombus-formation analysis system-based bleeding risk model in patients undergoing percutaneous coronary intervention

BACKGROUND

Antithrombotic therapy is established for the treatment of various cardiovascular events. However, it has been shown to increase the bleeding risk. Total Thrombus-formation Analysis System (T-TAS) is reported to be useful for evaluating thrombogenicity. Here, we estimated whether T-TAS is useful for predicting bleeding events risk in patients undergoing percutaneous coronary intervention (PCI).

METHODS

This was a retrospective, observational study at Kumamoto University Hospital between April 2017 and March 2019. Blood samples obtained on the day of PCI were used in T-TAS to compute the thrombus formation area under the curve (AUC) (AR₁₀-AUC₃₀, AUC for AR chip). We divided the study population into 2 groups according to the Academic Research Consortium for High Bleeding Risk (ARC-HBR) (182 patients in ARC-HBR positive, 118 in ARC-HBR negative). The primary endpoint was 1-year bleeding events that were defined by Bleeding Academic Research Consortium type2, 3, or 5.

RESULTS

The AR₁₀-AUC₃₀levels were significantly lower in the ARC-HBR positive group than in the ARC-HBR negative group (median [interquartile range] 1571.4 [1277.0-1745.3] vs. 1726.2 [1567.7-1799.6], p < 0.001). The combination of ARC-HBR and AR₁₀-AUC₃₀ could discriminate the bleeding risk, and improved predictive capacity compared with ARC-HBR by c-statistics. Decision-curve analysis also revealed that combining AR₁₀-AUC₃₀ with ARC-HBR ameliorated bleeding risk-prediction. In multivariate Cox hazards analyses, combining ARC-HBR with lower AR₁₀-AUC₃₀ levels was significantly associated with 1-year bleeding events.

CONCLUSIONS

The results highlight that AR₁₀-AUC₃₀ evaluated by T-TAS could be a potentially useful marker for predicting high bleeding risk in patients undergoing PCI.

Effects of glycemic control and hypoglycemia on Thrombus formation assessed using automated microchip flow chamber system: an exploratory observational study

Background

Thrombus formation is an important factor affecting cardiovascular events and venous thromboembolism in type 2 diabetes. However, it is unclear whether glycemic control reduces thrombogenicity. We investigated the effect of short-term glycemic control (STUDY 1) and hypoglycemia (STUDY 2) on thrombus formation using an automated microchip flow chamber system.

Methods

For STUDY 1, we recruited 10 patients with type 2 diabetes. Before and after 2 weeks of treatment, blood glucose was analyzed with a continuous glucose monitoring system, and thrombogenicity was analyzed with an automated microchip flow chamber system. For STUDY 2, we recruited 10 subjects without diabetes who underwent an insulin tolerance test. We evaluated the change in thrombogenic potential with hypoglycemia.

Results

STUDY1: The mean blood glucose level reduced from 10.1 ± 2.6 to 6.9 ± 0.97 mM (P < 0.01). T10, an indicator of thrombogenicity, significantly attenuated after glycemic control (338 ± 65 vs. 425 ± 117 s, P < 0.05). The attenuation in T10 was significantly correlated with changes in mean blood glucose level after treatment (r = - 0.718, P < 0.05). STUDY 2: Platelet function was enhanced with decreasing blood glucose; increased platelet function was strongly correlated with an increase in epinephrine.

Conclusions

We demonstrated attenuation in thrombogenicity with short-term comprehensive diabetes care and enhancement in thrombogenicity with hypoglycemia, using a new flow chamber system.

Trial registration

UMIN-CTR UMIN 000019899, registered 26-Jan-2015 (STUDY 2).

Reduction in thrombogenic activity and thrombocytopenia after transcatheter aortic valve implantation - The ATTRACTIVE-TTAS study

Introduction

Bleeding complications after transcatheter aortic valve implantation (TAVI) is a major problem in clinical practice. However, there is few information on thrombogenicity after TAVI. The aim of this study was to establish a monitoring of total thrombogenicity in perioperative TAVI using the Total Thrombus-formation Analysis System (T-TAS), a microchip-based flow chamber system for analysis of thrombus formation under flow condition.

Methods

Twenty-three patients with severe aortic stenosis who underwent TAVI between August 2017 and March 2018 at Kumamoto university hospital were enrolled. After exclusion, data of 21 patients were analyzed. Blood samples were obtained before, 2, 7, and 30 days after TAVI. Thrombogenicity were assessed by the T-TAS to compute the area under the curve (AUC) (AR₁₀-AUC₃₀) in the AR chip. We also measured platelet count, high-molecular-weight von Willebrand factor (HMW-vWF) multimers, and plasma thrombopoietin. Computational fluid dynamics (CFD) analysis was performed to calculate the wall shear stress (WSS).

Results

The AR₁₀-AUC₃₀ levels and platelet counts were significantly lower at 2 days post-TAVI, and then increased gradually. HMW-vWF multimers, and plasma thrombopoietin, were significantly higher at 2 days post-TAVI, compared with before TAVI. CFD analysis showed that WSS of the aortic valve and posterior ascending aortic wall were significantly lower after TAVI than before-TAVI. Multivariate analysis identified max velocity measured by echocardiography, platelet count, and D-dimer as significant determinants of AR₁₀-AUC₃₀, representing total thrombogenicity.

Conclusions

Although HMW-vWF multimers improved earlier after TAVI, total thrombogenic activity evaluated by T-TAS remained relatively low followed by improvement in thrombogenic activity at 30 days after TAVI.Clinical Trial Registration: https://clinicaltrials.gov. Unique identifiers: NCT03248232.

Inhibitory mechanisms of very low-dose rivaroxaban in non-ST-elevation myocardial infarction

Very low-dose (VLD) factor Xa (FXa) inhibition, in combination with acetylsalicylic acid (ASA) and clopidogrel, is associated with improved outcomes in patients with acute coronary syndrome (ACS) with a tolerable bleeding risk profile. To date, there are no data documenting platelet inhibition and the anticoagulatory effects of VLD FXa inhibition on top of guideline-adherent dual-antiplatelet therapy (DAPT) in patients with ACS. Patients with non-ST-elevation myocardial infarction (NSTEMI) receiving oral DAPT (ASA + clopidogrel, n = 20; or ASA + ticagrelor, n = 20) were prospectively enrolled in a nonrandomized study. Coagulation- and platelet-dependent thrombin generation (TG), measured by means of the calibrated automated thrombogram, were significantly decreased after in vitro and in vivo addition of rivaroxaban. As shown by a total thrombus-formation analysis approach, rivaroxaban treatment led to a significantly decreased coagulation-dependent (AR-chip) thrombus formation in patients treated with ASA plus P2Y₁₂ inhibitor (clopidogrel/ticagrelor), whereas the pure platelet-dependent (PL-chip) thrombus formation was not affected at all. Adjunctive rivaroxaban therapy was not associated with significant differences in platelet aggregation assessed by light-transmission aggregometry (LTA). Nevertheless, according to fluorescence-activated cell sorter analysis, VLD rivaroxaban treatment resulted in a significantly reduced expression of platelet HMGB-1, whereas P-selectin exposure was not affected. Furthermore, an enhanced effect of rivaroxaban on total thrombus formation and TG was observed in particular in clopidogrel nonresponder patients defined as adenosine 5'-diphosphate-induced LTA ≥40%. VLD rivaroxaban reduces thrombus formation and platelet-dependent TG in patients with ACS receiving DAPT, which can be of potential ischemic benefit. This trial was registered at www.clinicaltrials.gov as #NCT01417884.

Non-vitamin K antagonist oral anticoagulants for pulmonary embolism: who, where and for how long?

INTRODUCTION

Acute pulmonary embolism (PE) is a relatively common cardiopulmonary emergency that is a major cause of hospitalization and morbidity and is the primary cause of mortality associated with venous thromboembolism (VTE). During the last decade, one of the biggest changes in the management of PE has been the approval of four non-vitamin K antagonist oral anticoagulants (NOACs; apixaban, dabigatran, edoxaban and rivaroxaban) for the treatment of PE and deep vein thrombosis and secondary prevention of VTE. Areas covered: This article reviews the evolving management of PE in the NOAC era and addresses three fundamental questions: who should receive NOACs over conventional heparin/vitamin K antagonist regimens for the treatment of acute PE; should patients be treated as inpatients or outpatients; and how long should patients be treated to reduce the risk of recurrence? Expert commentary: The management of PE is changing. NOACs provide new anticoagulant treatment options for patients with PE, based on Phase III clinical study results. The consistent efficacy and safety profile of NOACs across many PE patient subgroups, including the elderly, fragile patients, those with active cancer and high-risk (right ventricular dysfunction) patients, suggests NOAC use will increase among these patients.

Edoxaban Enhances Thromboprophylaxis by Physiotherapy After Total Knee Arthroplasty - The Randomized Controlled ESCORT-TKA Trial

BACKGROUND

The pharmacological advantage of combining physiotherapy with anticoagulants for the prevention of venous thromboembolism (VTE) after total knee arthroplasty (TKA) is not fully known. Herein we investigated the potential benefit of this combination therapy in patients undergoing TKA.

METHODS AND RESULTS

The 38 patients were randomly assigned to a physiotherapy group (n=19) or a physiotherapy plus 30 mg/day edoxaban group (n=19). The occurrence of VTE was evaluated, as were serial changes in parameters measured by the Total Thrombus-formation Analysis System, a novel system for quantitatively analyzing thrombus formation using microchips with thrombogenic surfaces (collagen plus tissue factor, atheroma [AR]-chip). Combination therapy significantly reduced the incidence of VTE after TKA compared with monotherapy (P=0.038). The area under the curve (AUC) of thrombus formation for the AR-chip (AR10-AUC30) was significantly lower in the combination group (P=0.001) on Day 7 after TKA than before TKA, but no significant change was observed with monotherapy (P=0.809). In 13 VTE-positive patients, AR10-AUC30was significantly lower in the combination group (n=3) than in the monotherapy group (n=10) on Day 7 (P=0.045).

CONCLUSIONS

The combination of physiotherapy and edoxaban significantly reduced the incidence of VTE after TKA compared with physiotherapy alone. However, it is possible that VTE occurrence after TKA is not only associated with thrombogenicity, but also rheological factors.