Biomarkers of coagulation, endothelial function, and fibrinolysis in critically ill patients with COVID-19: A single-center prospective longitudinal study

BACKGROUND

Immunothrombosis and coagulopathy in the lung microvasculature may lead to lung injury and disease progression in coronavirus disease 2019 (COVID-19). We aim to identify biomarkers of coagulation, endothelial function, and fibrinolysis that are associated with disease severity and may have prognostic potential.

METHODS

We performed a single-center prospective study of 14 adult COVID-19(+) intensive care unit patients who were age- and sex-matched to 14 COVID-19(-) intensive care unit patients, and healthy controls. Daily blood draws, clinical data, and patient characteristics were collected. Baseline values for 10 biomarkers of interest were compared between the three groups, and visualized using Fisher's linear discriminant function. Linear repeated-measures mixed models were used to screen biomarkers for associations with mortality. Selected biomarkers were further explored and entered into an unsupervised longitudinal clustering machine learning algorithm to identify trends and targets that may be used for future predictive modelling efforts.

RESULTS

Elevated D-dimer was the strongest contributor in distinguishing COVID-19 status; however, D-dimer was not associated with survival. Variable selection identified clot lysis time, and antigen levels of soluble thrombomodulin (sTM), plasminogen activator inhibitor-1 (PAI-1), and plasminogen as biomarkers associated with death. Longitudinal multivariate k-means clustering on these biomarkers alone identified two clusters of COVID-19(+) patients: low (30%) and high (100%) mortality groups. Biomarker trajectories that characterized the high mortality cluster were higher clot lysis times (inhibited fibrinolysis), higher sTM and PAI-1 levels, and lower plasminogen levels.

CONCLUSIONS

Longitudinal trajectories of clot lysis time, sTM, PAI-1, and plasminogen may have predictive ability for mortality in COVID-19.

Factor XI as a Target for New Anticoagulants

Despite advances in anticoagulant therapy, thrombosis remains the leading cause of morbidity and mortality worldwide. Heparin and vitamin K antagonists (VKAs), the first anticoagulants to be used successfully for the prevention and treatment of thrombosis, are associated with a risk of bleeding. These agents target multiple coagulation factors. Thus, by activating antithrombin, heparin mainly inhibits factor Xa and thrombin, whereas VKAs lower the levels of the vitamin K-dependent clotting factors. Direct oral anticoagulants, which have replaced VKAs for many indications, inhibit only factor Xa or thrombin. Although the direct oral anticoagulants are associated with less bleeding than VKAs, bleeding remains their major side effect. Epidemiological and animal studies have identified factor XI as a target for potentially safer anticoagulant drugs because factor XI deficiency or inhibition protects against thrombosis and is associated with little or no bleeding. Several factor XI-directed strategies are currently under investigation. This article (1) reviews the rationale for the development of factor XI inhibitors, (2) identifies the agents in most advanced stages of development, (3) describes the results of completed clinical trials and provides a summary of those underway, and (4) highlights the opportunities and challenges for this next generation of anticoagulants.

Associations between model-predicted rivaroxaban exposure and patient characteristics and efficacy and safety outcomes in the prevention of venous thromboembolism

Anticoagulant plasma concentrations and patient characteristics might affect the benefit–risk balance of therapy. The study objective was to assess the impact of model-predicted rivaroxaban exposure and patient characteristics on outcomes in patients receiving rivaroxaban for venous thromboembolism (VTE) prophylaxis (VTE-P) after hip/knee replacement surgery. Post hoc exposure–response analyses were conducted using data from the phase 3 RECORD1–4 studies, in which 12,729 patients were randomized to rivaroxaban 10 mg once daily or enoxaparin for ≤ 39 days. Multivariate regression approaches were used to correlate model-predicted individual rivaroxaban exposures and patient characteristics with outcomes. In the absence of measured rivaroxaban exposure, exposure estimates were predicted based on individual increases in prothrombin time (PT) and by making use of the known correlation between rivaroxaban plasma concentration and dynamics of PT. No significant associations between rivaroxaban exposure and total VTE or major bleeding were identified. A significant association between exposure and a composite of major or non-major clinically relevant (NMCR) bleeding from day 4 after surgery was observed. The relationship was shallow, with an approximate predicted absolute increase in a composite of major or NMCR bleeding from 1.08 [95% confidence interval (CI) 0.76–1.54] to 2.18% (95% CI 1.51–3.17) at the 5th and 95th percentiles of trough plasma concentration, respectively. In conclusion, based on the underlying data and analysis, no reliable target window for exposure with improved benefit–risk could be identified within the investigated exposure range. Hence, monitoring rivaroxaban levels is unlikely to be beneficial in VTE-P.

Associations between model-predicted rivaroxaban exposure and patient characteristics and efficacy and safety outcomes in patients with non-valvular atrial fibrillation

Rivaroxaban exposure and patient characteristics may affect the rivaroxaban benefit–risk balance. This study aimed to quantify associations between model-predicted rivaroxaban exposure and patient characteristics and efficacy and safety outcomes in patients with non-valvular atrial fibrillation (NVAF), using data from the phase 3 ROCKET AF trial (NCT00403767). In ROCKET AF, 14,264 patients with NVAF were randomized to rivaroxaban (20 mg once daily [OD], or 15 mg OD if creatinine clearance was 30–49 mL/min) or dose-adjusted warfarin (median follow-up: 707 days); rivaroxaban plasma concentration was measured in a subset of 161 patients. In this post hoc exposure–response analysis, a multivariate Cox model was used to correlate individual predicted rivaroxaban exposures and patient characteristics with time-to-event efficacy and safety outcomes in 7061 and 7111 patients, respectively. There was no significant association between model-predicted rivaroxaban trough plasma concentration (C_trough) and efficacy outcomes. Creatinine clearance and history of stroke were significantly associated with efficacy outcomes. C_trough was significantly associated with the composite of major or non-major clinically relevant (NMCR) bleeding (hazard ratio [95th percentile vs. median]: 1.26 [95% confidence interval 1.13–1.40]) but not with major bleeding alone. The exposure–response relationship for major or NMCR bleeding was shallow with no clear threshold for an acceleration in risk. History of gastrointestinal bleeding had a greater influence on safety outcomes than C_trough. These results support fixed rivaroxaban 15 mg and 20 mg OD dosages in NVAF. Therapeutic drug monitoring is unlikely to offer clinical benefits in this indication beyond evaluation of patient characteristics.

Treatment-Dose LMWH versus Prophylactic/Intermediate Dose Heparins in High-Risk COVID-19 Inpatients: Rationale and Design of the HEP-COVID Trial

Coronavirus disease-2019 (COVID-19) has been associated with significant risk of venous thromboembolism (VTE), arterial thromboembolism (ATE), and mortality particularly among hospitalized patients with critical illness and elevated D-dimer (Dd) levels. Conflicting data have yet to elucidate optimal thromboprophylaxis dosing. HEP-COVID (NCT04401293) is a phase 3, multicenter, pragmatic, prospective, randomized, pseudo-blinded, active control trial to evaluate efficacy and safety of therapeutic-dose low-molecular-weight heparin (LMWH) versus prophylactic-/intermediate-dose LMWH or unfractionated heparin (UFH) for prevention of a primary efficacy composite outcome of VTE, ATE, and all-cause mortality 30 ± 2 days post-enrollment. Eligible patients have COVID-19 diagnosis by nasal swab or serologic testing, requirement for supplemental oxygen per investigator judgment, and Dd >4 × upper limit of normal (ULN) or sepsis-induced coagulopathy score ≥4. Subjects are randomized to enoxaparin 1 mg/kg subcutaneous (SQ)/two times a day (BID) (creatinine clearance [CrCl] ≥ 30 mL/min) or 0.5 mg/kg (CrCl 15-30 mL/min) versus local institutional prophylactic regimens including (1) UFH up to 22,500 IU (international unit) daily (divided BID or three times a day), (2) enoxaparin 30 and 40 mg SQ QD (once daily) or BID, or (3) dalteparin 2,500 IU or 5,000 IU QD. The principal safety outcome is major bleeding. Events are adjudicated locally. Based on expected 40% relative risk reduction with treatment-dose compared with prophylactic-dose prophylaxis, 308 subjects will be enrolled (assuming 20% drop-out) to achieve 80% power. Distinguishing design features include an enriched population for the composite endpoint anchored on Dd >4 × ULN, stratification by intensive care unit (ICU) versus non-ICU, and the ability to capture asymptomatic proximal deep venous thrombosis via screening ultrasonography prior to discharge.

Recent Randomized Trials of Antithrombotic Therapy for Patients With COVID-19: JACC State-of-the-Art Review

Endothelial injury and microvascular/macrovascular thrombosis are common pathophysiological features of coronavirus disease-2019 (COVID-19). However, the optimal thromboprophylactic regimens remain unknown across the spectrum of illness severity of COVID-19. A variety of antithrombotic agents, doses, and durations of therapy are being assessed in ongoing randomized controlled trials (RCTs) that focus on outpatients, hospitalized patients in medical wards, and patients critically ill with COVID-19. This paper provides a perspective of the ongoing or completed RCTs related to antithrombotic strategies used in COVID-19, the opportunities and challenges for the clinical trial enterprise, and areas of existing knowledge, as well as data gaps that may motivate the design of future RCTs.

Venous thromboembolism in Asia and worldwide: Emerging insights from GARFIELD-VTE

BACKGROUND

Although epidemiological studies report a lower risk of venous thromboembolism (VTE) than in the Western world, VTE rates in Asia may be underestimated. Furthermore, it is uncertain whether VTE outcomes differ in Asia and the rest of the world (ROW).

METHODS

GARFIELD-VTE is a global, prospective, non-interventional study of real-world treatment practices. In this study, we compared baseline characteristics, treatment patterns, and 12-month outcomes in Asia and ROW.

RESULTS

Of the 10,684 enrolled patients, 1822 (17.1%) were Asian (China n = 420, Hong Kong n = 98, Japan n = 148, Malaysia n = 244, South Korea n = 343, Taiwan n = 232, Thailand n = 337). Compared with ROW patients, those from Asia were more often female (57.4% vs. 48.0%), non-smokers (74.0% vs. 58.9%) and had a lower BMI (24.8 kg/m² vs. 29.1 kg/m²). Asian patients were more likely to be managed in the hospital (86.9% vs. 70.4%) and to have active cancer (19.8% vs. 8.1%) or a history of cancer (19.1% vs. 12.0%). Asian patients received no anticoagulation more frequently than ROW patients (6.5% vs. 2.1%). Over 12-months follow-up, the rate of all-cause mortality (per 100 person-years [95% confidence interval]) was higher in Asians (15.2 [13.4-17.3] vs. 5.9 [5.4-6.5]). Adjusted hazard ratios indicated a higher risk of all-cause mortality in Asian patients than the ROW (1.32 [1.08-1.62]). The frequencies of major bleeding and recurrent VTE were similar.

CONCLUSION

Asian patients have different risk profiles, treatment patterns and a higher risk of mortality compared with the ROW.

Association Between Asymptomatic Proximal Deep Vein Thrombosis and Mortality in Acutely Ill Medical Patients

Background Asymptomatic proximal deep vein thrombosis (DVT) is an end point frequently used to evaluate the efficacy of anticoagulant thromboprophylaxis in medical patients. Recently, the clinical relevance of asymptomatic DVT has been challenged. Methods and Results The objective of this study was to evaluate the relationship between asymptomatic proximal DVT and all-cause mortality (ACM) using a cohort analysis of a randomized trial for the prevention of venous thromboembolism (VTE) in acutely ill medical patients. Patients who received at least 1 dose of study drug and had an adequate compression ultrasound examination of the legs on either day 10 or day 35 were categorized into 1 of 3 cohorts: no VTE, asymptomatic proximal DVT, or symptomatic DVT. Cox proportional hazards model, with adjustment for significant independent predictors of mortality, were used to compare the incidences of ACM. Of the 7036 patients, 6776 had no VTE, 236 had asymptomatic DVT, and 24 had symptomatic VTE. The incidence of ACM was 4.8% in patients without VTE. Both asymptomatic proximal DVT (mortality, 11.4%; hazard ratio [HR], 2.31; 95% CI, 1.52-3.51; P<0.0001) and symptomatic VTE (mortality, 29.2%; HR, 9.42; 95% CI, 4.18-21.20; P<0.0001) were independently associated with significant increases in ACM. The analysis was post hoc, and ultrasound results were not available for all patients. Adjustment for baseline variables significantly associated with ACM may not fully compensate for differences. Conclusions Asymptomatic proximal DVT is associated with higher ACM than no VTE and remains a relevant end point to evaluate the efficacy of anticoagulant thromboprophylaxis in medical patients. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT00571649.

Polysiloxane Nanofilaments Infused with Silicone Oil Prevent Bacterial Adhesion and Suppress Thrombosis on Intranasal Splints

Like all biofluid-contacting medical devices, intranasal splints are highly prone to bacterial adhesion and clot formation. Despite their widespread use and the numerous complications associated with infected splints, limited success has been achieved in advancing their safety and surface biocompatibility, and, to date, no surface-coating strategy has been proposed to simultaneously enhance the antithrombogenicity and bacterial repellency of intranasal splints. Herein, we report an efficient, highly stable lubricant-infused coating for intranasal splints to render their surfaces antithrombogenic and repellent toward bacterial cells. Lubricant-infused intranasal splints were prepared by creating superhydrophobic polysiloxane nanofilament (PSnF) coatings using surface-initiated polymerization of n-propyltrichlorosilane (n-PTCS) and further infiltrating them with a silicone oil lubricant. Compared with commercially available intranasal splints, lubricant-infused, PSnF-coated splints significantly attenuated plasma and blood clot formation and prevented bacterial adhesion and biofilm formation for up to 7 days, the typical duration for which intranasal splints are kept. We further demonstrated that the performance of our engineered biointerface is independent of the underlying substrate and could be used to enhance the hemocompatibility and repellency properties of other medical implants such as medical-grade catheters.

Heavy menstrual bleeding in women on anticoagulant treatment for venous thromboembolism: Comparison of high- and low-dose rivaroxaban with aspirin

BACKGROUND

Rivaroxaban may induce heavy menstrual bleeding. It is unknown if this effect is dose related or if rivaroxaban is associated with more menstrual bleeding than aspirin.

OBJECTIVES

To demonstrate and compare menstrual patterns and actions taken among women receiving aspirin and two doses of rivaroxaban.

METHODS

The EINSTEIN-CHOICE trial compared once-daily rivaroxaban 20 mg, rivaroxaban 10 mg, and aspirin 100 mg for extended treatment of venous thromboembolism in patients who had completed 6 to 12 months of anticoagulant therapy. In 362 women with menstrual cycles, menstrual flow duration and intensity assessed at days 30, 90, 180, and 360 were compared with those before starting anticoagulant therapy.

RESULTS

Menstrual flow duration increased in 12%-18% of the 134 women given 20-mg rivaroxaban, in 6% to 12% of 120 women given 10-mg rivaroxaban, and in 9% to 12% of 108 women given aspirin. Corresponding increases in flow intensity were 19% to 24%, 14% to 21%, and 13% to 20%. The odds ratios (ORs) for increased menstrual flow duration were 1.36 (95% confidence interval [CI], 0.62-2.96) for rivaroxaban 20 mg versus aspirin, 0.77 (95% CI, 0.33-1.81) for rivaroxaban 10 mg versus aspirin, and 0.57 (95% CI, 0.26-1.25) for rivaroxaban 10 mg versus 20 mg. The ORs for increased menstrual flow intensity were 1.41 (95% CI, 0.67-2.99), 1.07 (95% CI, 0.49-2.34), and 0.76 (95% CI, 0.37- 1.57), respectively.

CONCLUSIONS

There were no statistically significant differences in menstrual hemorrhage patterns between women treated with 10 or 20 mg of rivaroxaban and aspirin. Compared with 10-mg rivaroxaban or aspirin, 20-mg rivaroxaban showed numerically more often increased menstrual flow duration and intensity.

Provoked versus unprovoked venous thromboembolism: Findings from GARFIELD-VTE

INTRODUCTION

Venous thromboembolism (VTE) has a long-term risk of recurrence, dependent on the presence or absence of provoking risk factors at the time of the event.

OBJECTIVE

To compare clinical characteristics, anticoagulant patterns, and 12-month outcomes in patients with transient provoking factors, active cancer, and unprovoked VTE.

METHODS

The Global Anticoagulant Registry in the FIELD (GARFIELD)-VTE is a prospective, observational study that enrolled 10 207 patients with objectively diagnosed VTE from 415 sites in 28 countries.

RESULTS

Patients with transient provoking factors were younger (53.0 years) and more frequently women (61.2%) than patients with unprovoked VTE (60.3 years; 43.0% women) or active cancer (63.6 years; 51.7% women). After 6 months, 59.1% of patients with transient provoking factors remained on anticoagulation, compared to 71.3% with unprovoked VTE and 47.3% with active cancer. At 12 months, this decreased to 36.7%, 51.5%, and 25.4%, respectively. The risk of mortality (hazard ratio [HR], 1.21; 95% confidence interval [CI], 0.90-1.62), recurrent VTE (HR, 0.84; 95% CI, 0.62-1.14), and major bleeding (HR, 1.26; 95% CI, 0.86-1.85) was comparable in patients with transient provoking factors and unprovoked VTE. Patients with minor and major transient provoking factors had a similar risk of recurrent VTE (HR, 0.99; 95% CI, 0.59-1.66), but those with major transient risk factors had a lower risk of death (HR, 0.61; 95% CI, 0.38-0.98).

CONCLUSION

At 1 year, nearly 40% of patients with transient provoking factors and slightly over half of patients with unprovoked VTE were on anticoagulant treatment. Event rates were comparable between the two groups. Risk of death was higher in patients with minor transient factors than in those with major transient factors.

Pregnancy-Associated Venous Thromboembolism: Insights from GARFIELD-VTE

Introduction  The risk of venous thromboembolism (VTE) increases during pregnancy and the puerperium such that VTE is a leading cause of maternal mortality.

Methods  We describe the clinical characteristics, diagnostic strategies, treatment patterns, and outcomes of women with pregnancy-associated VTE (PA-VTE) enrolled in the Global Anticoagulant Registry in the FIELD (GARFIELD)-VTE. Women of childbearing age (<45 years) were stratified into those with PA-VTE ( n  = 183), which included pregnant patients and those within the puerperium, and those with nonpregnancy associated VTE (NPA-VTE; n  = 1,187). Patients with PA-VTE were not stratified based upon the stage of pregnancy or puerperium.

Results  Women with PA-VTE were younger (30.5 vs. 34.8 years), less likely to have pulmonary embolism (PE) (19.7 vs. 32.3%) and more likely to have left-sided deep vein thrombosis (DVT) (73.9 vs. 54.8%) compared with those with NPA-VTE. The most common risk factors in PA-VTE patients were hospitalization (10.4%), previous surgery (10.4%), and family history of VTE (9.3%). DVT was typically diagnosed by compression ultrasonography (98.7%) and PE by chest computed tomography (75.0%). PA-VTE patients more often received parenteral (43.2 vs. 15.1%) or vitamin K antagonists (VKA) (9.3 vs. 7.6%) therapy alone. NPA-VTE patients more often received a DOAC alone (30.2 vs. 13.7%). The risk (hazard ratio [95% confidence interval]) of all-cause mortality (0.59 [0.18–1.98]), recurrent VTE (0.82 [0.34–1.94]), and major bleeding (1.13 [0.33–3.90]) were comparable between PA-VTE and NPA-VTE patients. Uterine bleeding was the most common complication in both groups.

Conclusion  VKAs or DOACs are widely used for treatment of PA-VTE despite limited evidence for their use in this population. Rates of clinical outcomes were comparable between groups.

New anticoagulants: Moving beyond the direct oral anticoagulants

Although anticoagulants have been in use for more than 80 years, heparin and vitamin K antagonists were the sole available options until recently. Although these agents revolutionized the prevention and treatment of thrombotic diseases, their use has been hampered by the necessity for coagulation monitoring and by bleeding complications resulting in part from their multiple sites of action. Owing to advances in basic science, animal models, and epidemiology, the arsenal of available anticoagulants has expanded in the past two decades. This evolution has yielded many novel compounds that target single coagulation enzymes. Initially, thrombin and factor Xa were targeted because of their critical roles in coagulation. However, attention has now shifted to compounds that target upstream reactions, particularly those catalyzed by factors XIIa and XIa, which are part of the contact system. This shift is predicated on epidemiological and experimental evidence suggesting that these factors are more important for thrombosis than for hemostasis. With the goal of developing a new class of anticoagulants associated with a lower risk of bleeding than currently available agents, dozens of drugs targeting the contact system are now in development. This article focuses on the rationale, development, and testing of these new agents with a concentration on those that have reached or completed phase 2 evaluation for at least one indication.

Anticoagulation for Patients with Venous Thromboembolism: When is Extended Treatment Required?

The need for extended venous thromboembolism (VTE) treatment beyond 3 to 6 months is usually determined by balancing the risk of recurrence if treatment is stopped against the risk of bleeding from continuing treatment. The risk of recurrence, and in turn the decision to extend, can be determined through the nature of the index event. Patients with VTE provoked by surgery or trauma (major transient risk factors) are recommended to receive 3 months of anticoagulation therapy because their risk of recurrence is low, whereas patients with VTE provoked by a major persistent risk factor, such as cancer, or those considered to have “unprovoked” VTE, are recommended to receive an extended duration of therapy based on an established high risk of recurrence. Nonetheless, recent evidence and new guidance identify that this approach fails to consider patients with risk factors classed as minor transient (e.g., impaired mobility and pregnancy) or minor persistent (e.g., inflammatory bowel disease and congestive heart disease). Indeed, the risk of recurrence with respect to VTE provoked by minor persistent risk factors has been demonstrated to be not dissimilar to that of VTE without identifiable risk factors. This review provides an overview of the available data on the risk of recurrence according to the underlying cause of VTE, a critical evaluation of evidence from clinical studies on the available anticoagulants for extended VTE treatment, models of risk prediction for recurrent VTE and bleeding, and guidance on how to apply the evidence in practice.

Treatment of cancer-associated thrombosis: The evolution of anticoagulant choice and clinical insights into practical management

Low-molecular-weight heparin (LMWH) therapy is recommended over vitamin K antagonists (VKAs) for the treatment of cancer-associated thrombosis (CAT) and extended therapy is recommended in those with active cancer to prevent recurrent thrombosis. However, the inconvenience of daily subcutaneous injections and the cost of LMWH therapy hinder long-term use. Observational data demonstrate that persistence with LMWH therapy is low in clinical practice and that many patients are switched to oral alternatives - namely VKAs and direct oral anticoagulants (DOACs). Recently, the efficacy and safety of apixaban, edoxaban, and rivaroxaban versus LMWH therapy for the treatment of CAT have been demonstrated in randomized trials. This review provides a critical evaluation of studies with DOACs in this setting and an update on the guidance regarding anticoagulant use for the treatment of CAT. In recognition of the heterogeneity of patients with cancer and the challenges of CAT, patient cases with expert clinical perspectives are presented.

Recent advances in understanding, diagnosing and treating venous thrombosis

Focusing on the current state of the art, this article (a) describes recent advances in the understanding of the pathogenesis of venous thromboembolism (VTE), (b) discusses current approaches for the prevention, diagnosis and treatment of VTE, (c) outlines the role of aspirin for VTE prevention and treatment, and (d) highlights the unmet needs in VTE management and describes novel approaches to address them.

Assessment of Outcomes Among Patients With Venous Thromboembolism With and Without Chronic Kidney Disease

IMPORTANCE

Patients with venous thromboembolism (VTE) and concomitant chronic kidney disease (CKD) have been reported to have a higher risk of thrombosis and major bleeding complications compared with patients without concomitant CKD. The use of anticoagulation therapy is challenging, as many anticoagulant medications are excreted by the kidney. Large-scale data are needed to clarify the impact of CKD for anticoagulant treatment strategies and clinical outcomes of patients with VTE.

OBJECTIVE

To compare clinical characteristics, treatment patterns, and 12-month outcomes among patients with VTE and concomitant moderate to severe CKD (stages 3-5) vs patients with VTE and mild to no CKD (stages 1-2) in a contemporary international registry.

DESIGN, SETTING, AND PARTICIPANTS

The Global Anticoagulant Registry in the Field-Venous Thromboembolism (GARFIELD-VTE) study is a prospective noninterventional investigation of real-world treatment practices. A total of 10 684 patients from 415 sites in 28 countries were enrolled in the GARFIELD-VTE between May 2014 and January 2017. This cohort study included 8979 patients (6924 patients with mild to no CKD and 2055 patients with moderate to severe CKD) who had objectively confirmed VTE within 30 days before entry in the registry. Chronic kidney disease stages were defined by estimated glomerular filtration rates. Data were extracted from the study database on December 8, 2018, and analyzed between May 1, 2019, and July 30, 2020.

EXPOSURE

Moderate to severe CKD vs mild to no CKD.

MAIN OUTCOMES AND MEASURES

The primary outcomes were all-cause mortality, recurrent VTE, and major bleeding. Event rates and 95% CIs were calculated and expressed per 100 person-years. Hazard ratios (HRs) were estimated with Cox proportional hazards regression models and adjusted for relevant confounding variables. All-cause mortality was considered a competing risk for other clinical outcomes in the estimation of cumulative incidences.

RESULTS

Of the 10 684 patients with objectively confirmed VTE, serum creatinine data were available for 8979 patients (84.0%). Of those, 4432 patients (49.4%) were female and 5912 patients (65.8%) were White; 6924 patients (77.1%; median age, 57 years; interquartile range [IQR], 44-69 years) were classified as having mild to no CKD, and 2055 patients (22.9%; median age, 70 years; IQR, 59-78 years) were classified as having moderate to severe CKD. Calculations using the equation from the Modification of Diet in Renal Disease study indicated that, among the 6924 patients with mild to no CKD, 2991 patients had stage 1 CKD, and 3933 patients had stage 2 CKD; among the 2055 patients with moderate to severe CKD, 1650 patients had stage 3 CKD, 190 patients had stage 4 CKD, and 215 patients had stage 5 CKD. The distribution of VTE presentation was comparable between groups. In total, 1171 patients (57.0%) with moderate to severe CKD and 4079 patients (58.9%) with mild to no CKD presented with deep vein thrombosis alone, 547 patients (26.6%) with moderate to severe CKD and 1723 patients (24.9%) with mild to no CKD presented with pulmonary embolism alone, and 337 patients (16.4%) with moderate to severe CKD and 1122 patients (16.2%) with mild to no CKD presented with both pulmonary embolism and deep vein thrombosis. Compared with patients with mild to no CKD, patients with moderate to severe CKD were more likely to be female (3259 women [47.1%] vs 1173 women [57.1%]) and older than 65 years (2313 patients [33.4%] vs 1278 patients [62.2%]). At baseline, the receipt of parenteral therapy alone was comparable between the 2 groups (355 patients [17.3%] with moderate to severe CKD vs 1253 patients [18.1%] with mild to no CKD). Patients with moderate to severe CKD compared with those with mild to no CKD were less likely to be receiving direct oral anticoagulant therapy, either alone (557 patients [27.1%] vs 2139 patients [30.9%]) or in combination with parenteral therapy (319 patients [15.5%] vs 1239 patients [17.9%]). Patients with moderate to severe CKD had a higher risk of all-cause mortality (adjusted hazard ratio [aHR], 1.44; 95% CI, 1.21-1.73), major bleeding (aHR, 1.40; 95% CI, 1.03-1.90), and recurrent VTE (aHR, 1.40; 95% CI, 1.10-1.77) than patients with mild to no CKD.

CONCLUSIONS AND RELEVANCE

In this study of patients with VTE, the presence of moderate to severe CKD was associated with increases in the risk of death, VTE recurrence, and major bleeding compared with the presence of mild to no CKD.

Activated thrombin-activatable fibrinolysis inhibitor (TAFIa) attenuates fibrin-dependent plasmin generation on thrombin-activated platelets

BACKGROUND

Thrombin-activated platelets can promote fibrinolysis by binding plasminogen in a fibrinogen-dependent manner and enhancing its activation by tissue-type plasminogen activator (t-PA). Whether t-PA also binds to activated platelets and the mechanism for regulation of platelet-dependent fibrinolysis remain unknown.

OBJECTIVES

Determine the mechanism of plasminogen and t-PA binding on thrombin-activated platelets and its regulation by activated thrombin-activatable fibrinolysis inhibitor (TAFIa).

METHODS

Plasminogen and t-PA binding with or without TAFIa treatment was quantified using flow cytometry. Plasmin generation on platelets was quantified using a plasmin-specific substrate. Mass spectrometry analyses identified fibrinogen as a potential target of TAFIa. Thrombus formation was studied in mice lacking fibrinogen (Fg-/- ) using intravital microscopy.

RESULTS

Plasminogen and t-PA bind to platelets activated by thrombin but not by other agonists, including protease-activated receptor agonists (PAR-AP). Plasminogen binds via its kringle domains because ε-aminocaproic acid eliminates binding, whereas t-PA binds via its finger and kringle domains. Plasminogen binding is fibrinogen-dependent because it is abolished on (a) Fg-/- platelets, and (b) thrombi in Fg-/- mice. Binding requires thrombin-mediated fibrinogen modification because addition of batroxobin to PAR-AP activated platelets has no effect on plasminogen binding but induces t-PA binding. TAFIa reduces plasminogen and t-PA binding to thrombin-activated platelets and attenuates plasmin generation in a concentration-dependent manner. Mass spectrometry identified K556 on the fibrinogen alpha-chain as a potential thrombin cleavage site that generates a TAFIa sensitive C-terminal lysine residue.

CONCLUSION

These findings provide novel mechanistic insights into how platelets activated by thrombin at sites of vascular injury can influence fibrinolysis.

Single and multi-functional coating strategies for enhancing the biocompatibility and tissue integration of blood-contacting medical implants

Device-associated clot formation and poor tissue integration are ongoing problems with permanent and temporary implantable medical devices. These complications lead to increased rates of mortality and morbidity and impose a burden on healthcare systems. In this review, we outline the current approaches for developing single and multi-functional surface coating techniques that aim to circumvent the limitations associated with existing blood-contacting medical devices. We focus on surface coatings that possess dual hemocompatibility and biofunctionality features and discuss their advantages and shortcomings to providing a biocompatible and biodynamic interface between the medical implant and blood. Lastly, we outline the newly developed surface modification techniques that use lubricant-infused coatings and discuss their unique potential and limitations in mitigating medical device-associated complications.

Impact of concomitant antiplatelet therapy on the efficacy and safety of direct oral anticoagulants for acute venous thromboembolism: Systematic review and meta-analysis

BACKGROUND

Direct oral anticoagulants (DOACs) are recommended over vitamin K antagonists (VKAs) for the treatment of venous thromboembolism (VTE). Concomitant antiplatelet therapy may potentiate the antithrombotic effects of DOACs.

OBJECTIVES

We evaluated the impact of concomitant antiplatelet therapy on the efficacy and safety of DOACs.

PATIENTS/METHODS

MEDLINE, EMBASE, and Clinicaltrial.gov were searched for randomized controlled trials of DOACs for the treatment of acute VTE. The efficacy outcome was symptomatic recurrent VTE and VTE-related death; the primary safety outcome was major bleeding.

RESULTS

Six randomized controlled trials included 26 924 patients of whom 3550 (13.2%) received concomitant antiplatelet therapy, mainly aspirin (67.7%). Concomitant antiplatelet therapy did not reduce the incidence of recurrent VTE and VTE-related death with any oral anticoagulant (odds ratio [OR] 1.17; 95% confidence interval [CI], 0.92-1.48), with DOACs (OR 1.21; 95% CI, 0.86-1.71), or VKAs alone (OR 1.16; 95% CI, 0.77-1.73). Compared with no antiplatelet therapy, concomitant antiplatelet therapy was associated with a higher risk of major bleeding in patients with any oral anticoagulant (OR 1.79; 95% CI, 1.22-2.63), DOACs (OR 1.89; 95% CI, 1.04-3.44), or VKAs (OR 1.73; 95% CI, 1.16-2.59). In patients receiving concomitant antiplatelet therapy, there were no statistically significant differences in efficacy or safety outcomes with DOACs or VKAs (OR 0.99; 95% CI, 0.64-1.51, and OR 0.68; 95% CI, 0.32-1.45, respectively).

CONCLUSIONS

Concomitant use of antiplatelet therapy with oral anticoagulants does not appear to affect the risk of recurrent VTE and increases the risk of major bleeding.

COVID-19 and Thrombotic or Thromboembolic Disease: Implications for Prevention, Antithrombotic Therapy, and Follow-Up: JACC State-of-the-Art Review

Coronavirus disease-2019 (COVID-19), a viral respiratory illness caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), may predispose patients to thrombotic disease, both in the venous and arterial circulations, because of excessive inflammation, platelet activation, endothelial dysfunction, and stasis. In addition, many patients receiving antithrombotic therapy for thrombotic disease may develop COVID-19, which can have implications for choice, dosing, and laboratory monitoring of antithrombotic therapy. Moreover, during a time with much focus on COVID-19, it is critical to consider how to optimize the available technology to care for patients without COVID-19 who have thrombotic disease. Herein, the authors review the current understanding of the pathogenesis, epidemiology, management, and outcomes of patients with COVID-19 who develop venous or arterial thrombosis, of those with pre-existing thrombotic disease who develop COVID-19, or those who need prevention or care for their thrombotic disease during the COVID-19 pandemic.

COVID-19 and Thrombotic or Thromboembolic Disease: Implications for Prevention, Antithrombotic Therapy, and Follow-Up: JACC State-of-the-Art Review

Coronavirus disease-2019 (COVID-19), a viral respiratory illness caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), may predispose patients to thrombotic disease, both in the venous and arterial circulations, because of excessive inflammation, platelet activation, endothelial dysfunction, and stasis. In addition, many patients receiving antithrombotic therapy for thrombotic disease may develop COVID-19, which can have implications for choice, dosing, and laboratory monitoring of antithrombotic therapy. Moreover, during a time with much focus on COVID-19, it is critical to consider how to optimize the available technology to care for patients without COVID-19 who have thrombotic disease. Herein, the authors review the current understanding of the pathogenesis, epidemiology, management, and outcomes of patients with COVID-19 who develop venous or arterial thrombosis, of those with pre-existing thrombotic disease who develop COVID-19, or those who need prevention or care for their thrombotic disease during the COVID-19 pandemic.

Pharmacological Agents Targeting Thromboinflammation in COVID-19: Review and Implications for Future Research

Coronavirus disease 2019 (COVID-19), currently a worldwide pandemic, is a viral illness caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The suspected contribution of thrombotic events to morbidity and mortality in COVID-19 patients has prompted a search for novel potential options for preventing COVID-19-associated thrombotic disease. In this article by the Global COVID-19 Thrombosis Collaborative Group, we describe novel dosing approaches for commonly used antithrombotic agents (especially heparin-based regimens) and the potential use of less widely used antithrombotic drugs in the absence of confirmed thrombosis. Although these therapies may have direct antithrombotic effects, other mechanisms of action, including anti-inflammatory or antiviral effects, have been postulated. Based on survey results from this group of authors, we suggest research priorities for specific agents and subgroups of patients with COVID-19. Further, we review other agents, including immunomodulators, that may have antithrombotic properties. It is our hope that the present document will encourage and stimulate future prospective studies and randomized trials to study the safety, efficacy, and optimal use of these agents for prevention or management of thrombosis in COVID-19.

Dabigatran Reversal With Idarucizumab in Patients With Renal Impairment

BACKGROUND

Dabigatran and idarucizumab, its reversal agent, are renally cleared.

OBJECTIVES

The purpose of this study was to determine the extent of reversal and outcomes according to baseline renal function in dabigatran-treated nondialysis patients receiving idarucizumab.

METHODS

In 503 patients in RE-VERSE AD (Reversal of Effects of Idarucizumab in Patients on Active Dabigatran), the extent of dabigatran reversal and clinical outcomes were compared according to baseline renal function (creatinine clearance: normal ≥80, mild 50 to <80, moderate 30 to <50, and severe <30 ml/min).

RESULTS

Compared with patients with normal renal function, those with impaired renal function were older, were more often women, and had lower body mass indexes, more comorbidities, higher CHADS₂ scores, and higher dabigatran plasma levels despite more frequent use of lower-dose dabigatran regimens. Regardless of renal function, median reversal measured by dilute thrombin time was 100% within 4 h of idarucizumab administration, and over 98% of patients achieved this with corresponding undetectable levels of unbound dabigatran. By 12 or 24 h, 56% of patients with severe, 29.1% with moderate, and 9.2% with mild renal impairment had dabigatran levels >20 ng/ml compared with 8.3% of patients with normal renal function at baseline. Time to cessation of bleeding and the proportion with normal hemostasis with procedures were similar regardless of renal function, but patients with severe renal impairment had higher 30- and 90-day mortality rates.

CONCLUSIONS

Idarucizumab completely reverses dabigatran in >98% of patients regardless of renal function. Although re-elevation of dabigatran levels within 12 to 24 h is more common with renal impairment, the time to bleeding cessation and the extent of hemostasis during procedures are similar. (Reversal of Dabigatran Anticoagulant Effect With Idarucizumab; NCT02104947).

Variation in the Association between Antineoplastic Therapies and Venous Thromboembolism in Patients with Active Cancer

Background Venous thromboembolism (VTE) is a major cause of death in cancer patients. Although patients with cancer have numerous risk factors for VTE, the relative contribution of cancer treatments is unclear.

Objective The objective of this study is to evaluate the association between cancer therapies and the risk of VTE.

Methods From UK Clinical Practice Research Datalink, data on patients with first cancer diagnosis between 2008 and 2016 were extracted along with information on hospitalization, treatments, and cause of death. Primary outcome was active cancer-associated VTE. To establish the independent effects of risk factors, adjusted subhazard ratios (adj-SHR) were calculated using Fine and Gray regression analysis accounting for death as competing risk.

Results Among 67,801 patients with a first cancer diagnosis, active cancer-associated VTE occurred in 1,473 (2.2%). During a median observation time of 1.2 years, chemotherapy, surgery, hormonal therapy, radiation therapy, and immunotherapy were given to 71.1, 37.2, 17.2, 17.5, and 1.4% of patients with VTE, respectively. The active cancers associated with the highest risk of VTE—as assessed by incidence rates—included pancreatic cancer, brain cancer, and metastatic cancer. Chemotherapy was associated with an increased risk of VTE (adj-SHR: 3.17, 95% confidence interval [CI]: 2.76–3.65) while immunotherapy with a not significant reduced risk (adj-SHR: 0.67, 95% CI: 0.30–1.52). There was no association between VTE and radiation therapy (adj-SHR: 0.91, 95% CI: 0.65–1.27) and hormonal therapies.

Conclusion VTE risk varies with cancer type. Chemotherapy was associated with an increased VTE risk, whereas with radiation and immunotherapy therapy, an association was not confirmed.

The contact activation system as a potential therapeutic target in patients with COVID-19

Coronavirus disease 2019 (COVID-19) is predicted to overwhelm health care capacity in the United States and worldwide, and, as such, interventions that could prevent clinical decompensation and respiratory compromise in infected patients are desperately needed. Excessive cytokine release and activation of coagulation appear to be key drivers of COVID-19 pneumonia and associated mortality. Contact activation has been linked to pathologic upregulation of both inflammatory mediators and coagulation, and accumulating preclinical and clinical data suggest it to be a rational therapeutic target in patients with COVID-19. Pharmacologic inhibition of the interaction between coagulation factors XI and XII has been shown to prevent consumptive coagulopathy, pathologic systemic inflammatory response, and mortality in at least 2 types of experimental sepsis. Importantly, inhibition of contact activation also prevented death from Staphylococcus aureus-induced lethal systemic inflammatory response syndrome in nonhuman primates. The contact system is likely dispensable for hemostasis and may not be needed for host immunity, suggesting it to be a reasonably safe target that will not result in immunosuppression or bleeding. As a few drugs targeting contact activation are already in clinical development, immediate clinical trials for their use in patients with COVID-19 are potentially feasible for the prevention or treatment of respiratory distress.

Combination Antiplatelet and Oral Anticoagulant Therapy in Patients With Coronary and Peripheral Artery Disease

Antiplatelet therapy is the mainstay for the treatment of acute and chronic arterial disease involving the coronary and peripheral beds. However, questions remain about optimal antithrombotic therapy for long-term treatment of chronic vascular disease. The observation that dual antiplatelet therapy with acetylsalicylic acid and clopidogrel was associated with lower thrombotic event rates than acetylsalicylic acid monotherapy in patients with acute coronary syndromes and those undergoing percutaneous coronary intervention changed the treatment paradigm. Moreover, the demonstration that more pharmacodynamically potent P2Y₁₂ inhibitors than clopidogrel were associated with fewer thrombotic event occurrences further solidified the dual antiplatelet therapy approach. However, recurrent thrombotic events occur in ≈1 in 10 patients in the first year following an acute coronary syndrome event, despite treatment with the most potent P2Y₁₂ inhibitors, a limitation that has stimulated interest in exploring the efficacy and safety of approaches using anticoagulants on top of antiplatelet therapy. These investigations have included treatment with very-low-dose oral anticoagulation, and even its replacement of acetylsalicylic acid in the presence of a P2Y₁₂ inhibitor, in patients stabilized after an acute coronary syndrome event. Recent basic and translational studies have suggested noncanonical effects of coagulation factor inhibition that may further modulate clinical benefits. This in-depth review will discuss developments in our understanding of the roles that platelets and coagulation factors play in atherothrombosis and review the rationale and clinical evidence for combining antiplatelet and oral anticoagulant therapy in patients with coronary and peripheral artery disease.

Thromboprophylaxis with Rivaroxaban in Acutely Ill Medical Patients with Renal Impairment: Insights from the MAGELLAN and MARINER Trials

Patients with renal impairment are at higher risk of thrombosis and bleeding than those with normal renal function. The optimal rivaroxaban dose for thromboprophylaxis in acutely ill medical patients with renal impairment is unknown. MARINER and MAGELLAN were multicenter, randomized clinical trials of rivaroxaban in acutely ill medical patients. Efficacy and safety outcomes in patients with renal impairment in MARINER (7.5 mg once daily) were compared with those in patients with normal renal function in MARINER (10 mg once daily) and in a subpopulation of MAGELLAN that excluded patients at high risk for bleeding at baseline (10 mg once daily). Compared with enoxaparin/placebo in the MAGELLAN subpopulation, the relative risk (RR) of symptomatic venous thromboembolism (VTE) and VTE-related death with rivaroxaban 10 mg in patients with renal impairment (RR = 0.62; 95% confidence interval [CI] 0.27–1.44) was similar to that in those with normal renal function (RR = 0.78; 95% CI 0.44–1.40), while in MARINER, the 7.5 mg dose did not reduce the risk in patients with renal impairment (hazard ratio = 1.00; 95% CI 0.52–1.92). Major bleeding with rivaroxaban 10 mg once daily was higher in patients with renal impairment than in those with normal renal function in MAGELLAN (1.54% vs. 0.98%) and in the MAGELLAN subpopulation (0.94% vs. 0.61%). At a dose of 10 mg once daily, rivaroxaban is effective for thromboprophylaxis in acutely ill medical patients with impaired or normal renal function. The safety of this regimen is enhanced without loss of efficacy by excluding patients at high risk for bleeding, but not by using a reduced-dose strategy.

Trial Registration ClinicalTrials.gov identifiers: NCT00571649 for the MAGELLAN trial, NCT02111564 for the MARINER trial.

Dual-pathway inhibition for secondary and tertiary antithrombotic prevention in cardiovascular disease

Advances in antiplatelet therapies for patients with cardiovascular disease have improved patient outcomes over time, but the challenge of balancing the risks of ischaemia and bleeding remains substantial. Moreover, many patients with cardiovascular disease have a residual risk of ischaemic events despite receiving antiplatelet therapy. Therefore, novel strategies are needed to prevent clinical events through mechanisms beyond platelet inhibition and with an acceptable associated risk of bleeding. The advent of non-vitamin K antagonist oral anticoagulants, which attenuate fibrin formation by selective inhibition of factor Xa or thrombin, has renewed the interest in dual-pathway inhibition strategies that combine an antiplatelet agent with an anticoagulant drug. In this Review, we highlight the emerging pharmacological rationale and clinical development of dual-pathway inhibition strategies for the prevention of atherothrombotic events in patients with different manifestations of cardiovascular disease, such as coronary artery disease, cerebrovascular disease and peripheral artery disease.

Effect of Osocimab in Preventing Venous Thromboembolism Among Patients Undergoing Knee Arthroplasty: The FOXTROT Randomized Clinical Trial

IMPORTANCE

The efficacy of factor XIa inhibition for thromboprophylaxis is unknown. Osocimab is a long-acting, fully human monoclonal antibody that inhibits factor XIa.

OBJECTIVE

To compare different doses of osocimab with enoxaparin and apixaban for thromboprophylaxis in patients who have undergone knee arthroplasty.

DESIGN, SETTING, AND PARTICIPANTS

Randomized, open-label, adjudicator-blinded, phase 2 noninferiority trial with observer blinding for osocimab doses, conducted at 54 hospitals in 13 countries. Adult patients undergoing unilateral knee arthroplasty were randomized from October 2017 through August 2018 and followed up until January 2019.

INTERVENTIONS

Single intravenous osocimab postoperative doses of 0.3 mg/kg (n = 107), 0.6 mg/kg (n = 65), 1.2 mg/kg (n = 108), or 1.8 mg/kg (n = 106); preoperative doses of 0.3 mg/kg (n = 109) or 1.8 mg/kg (n = 108); or 40 mg of subcutaneous enoxaparin once daily (n = 105) or 2.5 mg of oral apixaban twice daily (n = 105) for at least 10 days or until venography.

MAIN OUTCOMES AND MEASURES

The primary outcome was venous thromboembolism incidence between 10 and 13 days postoperatively (assessed by mandatory bilateral venography performed 10 to 13 days after surgery or confirmed symptomatic deep vein thrombosis or pulmonary embolism). A 5% noninferiority margin compared with enoxaparin was chosen. The primary safety outcome of major or clinically relevant nonmajor bleeding was assessed until 10 to 13 days postoperatively.

RESULTS

Of 813 randomized participants (mean [SD] age, 66.5 years [8.2 years]; body mass index, 32.7 [5.7]; and 74.2% women), 600 were included in the per-protocol population used for the primary analysis. The primary outcome occurred in 18 patients (23.7%) receiving 0.3 mg/kg, 8 (15.7%) receiving 0.6 mg/kg, 13 (16.5%) receiving 1.2 mg/kg, and 14 (17.9%) receiving 1.8 mg/kg of osocimab postoperatively; 23 (29.9%) receiving 0.3 mg/kg and 9 (11.3%) receiving 1.8 mg/kg of osocimab preoperatively; 20 (26.3%) receiving enoxaparin; and 12 (14.5%) receiving apixaban. Osocimab given postoperatively met criteria for noninferiority compared with enoxaparin with risk differences (1-sided 95% CIs) of 10.6% (95% CI, -1.2% to ∞) at the 0.6-mg/kg dose; 9.9% (95% CI, -0.9% to ∞) at the 1.2-mg/kg dose, and 8.4% (95% CI, -2.6 to ∞) at the 1.8-mg/kg dose. The preoperative dose of 1.8 mg/kg of osocimab met criteria for superiority compared with enoxaparin with a risk difference of 15.1%; 2-sided 90% CI, 4.9% to 25.2%). Postoperative and preoperative doses of 0.3 mg/kg of osocimab did not meet the prespecified criteria for noninferiority, with risk differences (1-sided 95% CIs) of 2.6% (95% CI, -8.9% to ∞) and -3.6% (95% CI, -15.5% to ∞), respectively. Major or clinically relevant nonmajor bleeding was observed in up to 4.7% of those receiving osocimab, 5.9% receiving enoxaparin, and 2% receiving apixaban.

CONCLUSIONS AND RELEVANCE

Among patients undergoing knee arthroplasty, postoperative osocimab 0.6 mg/kg, 1.2 mg/kg, and 1.8 mg/kg met criteria for noninferiority compared with enoxaparin, and the preoperative 1.8-mg/kg dose of osocimab met criteria for superiority compared with enoxaparin for the primary outcome of incidence of venous thromboembolism at 10 to 13 days postoperatively. Further studies are needed to establish efficacy and safety of osocimab relative to standard thromboprophylaxis.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03276143.

Rivaroxaban and Dabigatran for Suppression of Mechanical Heart Valve-Induced Thrombin Generation

BACKGROUND

Patients with mechanical heart valves (MHVs) require warfarin to prevent thromboembolism. Dabigatran was less effective than warfarin in patients with MHVs, which prompted a black box warning against the use of direct oral anticoagulants for this indication. However, rivaroxaban and apixaban, which inhibit factor Xa, have not been evaluated in patients with MHVs. To determine whether rivaroxaban and apixaban would be effective, we used MHV-induced thrombin generation assays to compare them with warfarin either alone or in combination with dabigatran.

METHODS

Thrombin generation in the absence or presence of MHV leaflets or sewing ring segments (SRSs) was quantified. Studies were done in control plasma; plasma from patients on warfarin; plasma containing varying concentrations of rivaroxaban, apixaban, or dabigatran alone; or plasma containing rivaroxaban plus dabigatran.

RESULTS

Mean endogenous thrombin potential (ETP) increased 1.2-fold, 1.5-fold, and 1.8-fold in the presence of leaflets, Teflon (Terumo Aortic (Sunrise, FL)) SRSs, or Dacron (Terumo Aortic (Sunrise, FL)) SRSs, respectively. Rivaroxaban and apixaban reduced ETP at concentrations above 50 ng/mL but were less effective than warfarin. When rivaroxaban and dabigatran were combined, they suppressed ETP in a more than additive manner.

CONCLUSIONS

Whereas warfarin suppresses MHV-induced thrombin generation, MHVs induce the generation of factor Xa in concentrations that overwhelm clinically relevant concentrations of rivaroxaban or apixaban. When used in combination, rivaroxaban and dabigatran are more effective than either agent is alone, suggesting that concomitant inhibition of factor Xa and thrombin is better than inhibition of either clotting enzyme alone.

Lubricant-Infused PET Grafts with Built-In Biofunctional Nanoprobes Attenuate Thrombin Generation and Promote Targeted Binding of Cells

New surface coatings that enhance hemocompatibility and biofunctionality of synthetic vascular grafts such as expanded poly(tetrafluoroethylene) (ePTFE) and poly(ethylene terephthalate) (PET) are urgently needed. Lubricant-infused surfaces prevent nontargeted adhesion and enhance the biocompatibility of blood-contacting surfaces. However, limited success has been made in incorporating biofunctionality onto these surfaces and generating biofunctional lubricant-infused coatings that both prevent nonspecific adhesion and enhance targeted binding of biomolecules remains a challenge. Here, a new generation of fluorosilanized lubricant-infused PET surfaces with built-in biofunctional nanoprobes is reported. These surfaces are synthesized by starting with a self-assembled monolayer of fluorosilane that is partially etched using plasma modification technique, thereby creating a hydroxyl-terminated fluorosilanized PET surface. Simultaneously, silanized nanoprobes are produced by amino-silanizing anti-CD34 antibody in solution and directly coupling the anti-CD34-aminosilane nanoprobes onto the hydroxyl terminated, fluorosilanized PET surface. The PET surfaces are then lubricated, creating fluorosilanized biofunctional lubricant-infused PET substrates. Compared with unmodified PET surfaces, the designed biofunctional lubricant-infused PET surfaces significantly attenuate thrombin generation and blood clot formation and promote targeted binding of endothelial cells from human whole blood.

Randomized phase 2 trial comparing JNJ-9375, a thrombin-directed antibody, with apixaban for prevention of venous thrombosis

BACKGROUND

JNJ-9375 is an antibody against exosite 1 on thrombin, inhibits substrate binding but not catalytic activity.

OBJECTIVE

To examine the possibility that JNJ-9375 attenuates thrombosis without affecting hemostasis, we compared the efficacy and safety of JNJ-9375 and apixaban.

METHODS

In this double-blind, double-dummy phase 2 trial, 308 patients undergoing knee arthroplasty were randomized to receive either a single postoperative intravenous infusion of JNJ-9375 in doses ranging from 0.3 to 1.8 mg/kg or apixaban (2.5 mg twice daily). The primary efficacy endpoint was the incidence of venous thromboembolism (assessed by mandatory unilateral venography or confirmed symptomatic events). The primary safety outcome was the composite of major, clinically relevant nonmajor, and minimal bleeding. Thrombin times were measured to assess JNJ-9375 activity.

RESULTS

A total of 239 of the 308 patients (77.6%) were included in the modified intention-to-treat analysis. Of these, 238 had evaluable venograms and one had symptomatic deep-vein thrombosis confirmed by ultrasound. Despite dose-dependent thrombin time prolongation, the primary efficacy outcome occurred in 59 of 190 patients (31.1%) in the combined JNJ-9375 groups as compared with 6 of 49 patients (12.2%) given apixaban (odds ratio 3.2; two-sided 80% confidence interval 1.8-5.8; P = .011). The excess events with JNJ-9375 compared with apixaban were consistent across all JNJ-9375 dosing cohorts and there was no evidence of improved efficacy with higher JNJ-9375 doses. There were no major bleeds with JNJ-9375 or apixaban, and rates of any bleeding were similar with the highest and lowest JNJ-9375 doses.

CONCLUSIONS

JNJ-9375 was safe but less effective than apixaban. This may reflect weak thrombin inhibition or inability of JNJ-9375 to attenuate the growth of thrombi that formed before drug administration.

Rivaroxaban plus aspirin for cardiovascular protection: Rationale for the vascular dose and dual pathway inhibition

This review provides the rationale for dual pathway inhibition with the combination of low-dose rivaroxaban (2.5 mg twice daily) to attenuate thrombin generation and aspirin (100 mg once daily) to reduce platelet activation. Such therapy has been licensed for secondary prevention in patients with coronary or peripheral artery disease.

Antithrombotic Agents

Recent advances in our understanding of the contribution of thrombin generation to arterial thrombosis and the role of platelets in venous thrombosis have prompted new treatment paradigms. Nonetheless, bleeding remains the major side effect of such treatments spurring the quest for new antithrombotic regimens with better benefit-risk profiles and for safer anticoagulants for existing and new indications. The aims of this article are to review the results of recent trials aimed at enhancing the benefit-risk profile of antithrombotic therapy and explain how these findings are changing our approach to the management of arterial and venous thrombosis. Focusing on these 2 aspects of thrombosis management, this article discusses 4 advances: (1) the observation that in some indications, lowering the dose of some direct oral anticoagulants reduces the risk of bleeding without compromising efficacy, (2) the recognition that aspirin is not only effective for secondary prevention of atherothrombosis but also for prevention of venous thromboembolism, (3) the finding that dual pathway inhibition with the combination of low-dose rivaroxaban to attenuate thrombin generation plus aspirin to reduce thromboxane A2-mediated platelet activation is superior to aspirin or rivaroxaban alone for prevention of atherothrombosis in patients with coronary or peripheral artery disease, and (4) the development of inhibitors of factor XI or XII as potentially safer anticoagulants.

Synergy of Dual Pathway Inhibition in Chronic Cardiovascular Disease

Although acetylsalicylic acid is of proven benefit for secondary prevention in patients with cardiovascular disease, the risk of recurrent ischemic events remains high. Intensification of antithrombotic therapy with more potent antiplatelet drugs, dual antiplatelet therapy, or vitamin K antagonists further reduces the risk of major adverse cardiovascular events compared with acetylsalicylic acid alone but increases the risk of bleeding without reducing mortality. In patients with prior coronary artery disease or peripheral arterial disease the COMPASS (Cardiovascular Outcomes for People Using Anticoagulation Strategies) trial revealed that compared with acetylsalicylic acid alone, dual pathway inhibition with low-dose rivaroxaban (2.5 mg twice-daily), an oral factor Xa inhibitor, plus acetylsalicylic acid reduced major adverse cardiovascular event by 24%, major adverse limb events by 47%, and mortality by 18%. Major bleeding was increased by 70%, but there was no increase in fatal or intracranial bleeding. This article (1) reviews the results of the COMPASS trial, (2) explains why dual pathway inhibition is superior to antiplatelet or anticoagulant therapy alone, (3) compares the results with rivaroxaban plus aspirin with those with other antithrombotic regimens, and (4) provides insight into how best to apply the COMPASS results into practice.

Clinical implications of incidental venous thromboembolism in cancer patients

Introduction

In cancer patients, current guidance suggests similar treatment for incidental and symptomatic venous thromboembolism (VTE), mainly based on retrospective data. We aimed to evaluate anticoagulant therapy in cancer patients with incidental and symptomatic VTE.

Methods

The Hokusai VTE Cancer Study was a randomised controlled trial comparing edoxaban with dalteparin for cancer-associated VTE. The primary outcome was the composite of first recurrent VTE or major bleeding. Secondary outcomes included major bleeding, recurrent VTE and mortality. Outcomes in patients with incidental and symptomatic VTE were evaluated during the 12-month study period.

Results

331 patients with incidental VTE and 679 patients with symptomatic VTE were enrolled, of whom the index event was confirmed by an independent radiologist. Median durations of anticoagulant treatment were 195 and 189 days, respectively. In patients with incidental VTE, the primary outcome occurred in 12.7% of patients, major bleeding in 6.6% of patients and recurrent VTE in 7.9% of patients. Out of the 26 VTE recurrences in patients with incidental VTE, five (31%) were incidental, seven (44%) were symptomatic and four (25%) were deaths for which pulmonary embolism could not be ruled out. In patients with symptomatic VTE, the primary outcome occurred in 13.8% of patients, major bleeding in 4.9% of patients and recurrent VTE in 10.9% of patients. All-cause mortality was similar in both groups.

Conclusion

Clinical adverse outcomes are substantial in both cancer patients with incidental and symptomatic VTE, supporting current guideline recommendations that suggest treating incidental VTE in the same manner as symptomatic VTE.

Edoxaban for treatment of venous thromboembolism in patient groups with different types of cancer: Results from the Hokusai VTE Cancer study

BACKGROUND

The safety and efficacy of edoxaban and dalteparin is unclear for several cancer groups.

METHODS

We evaluated the occurrence of the primary outcome in large cancer groups. The primary outcome was the composite of recurrent VTE or major bleeding over 12 months.

RESULTS

In patients with gastrointestinal cancer, the primary outcome occurred in 19.4% patients given edoxaban and in 15.0% given dalteparin (risk difference [RD], 4.4%; 95%-CI, -4.1% to 12.8%). The corresponding rates for edoxaban and dalteparin were 10.4% and 10.7% for lung cancer (RD, -0.3%; 95%-CI, -10.0% to 9.5%), 13.6% and 12.5% for urogenital cancer (RD, 1.1; 95%-CI, -10.1-12.4), 3.1% and 11.7% for breast cancer (RD, -8.6; 95%-CI, -19.3-2.2), 8.9% and 10.9% for hematological malignancies (RD, -2.0; 95%-CI, -13.1-9.1), and 10.4% and 17.4% for gynecological cancer (RD, -7.0; 95%-CI, -19.8-5.7). In the subgroup of gastrointestinal cancer, edoxaban was associated with a 3.5% lower absolute risk of recurrent VTE and a 7.9% higher risk of major bleeding.

CONCLUSION

Edoxaban has a similar risk-benefit ratio to dalteparin in most cancer groups. In those with gastrointestinal cancer, the lower risk of recurrent VTE and the advantages of oral therapy need to be balanced against the increased risk of major bleeding.

2350Evaluation of the pharmacodynamics of a ticagrelor reversal agent PB2452

Background

Ticagrelor is a P2Y12 antagonist used in combination with aspirin to reduce the risk of recurrent thrombotic cardiovascular events in patients with acute coronary syndrome. Ticagrelor is associated with a risk for spontaneous major bleeding or bleeding associated with invasive procedures, particularly cardiac surgery. A rapid-acting reversal agent for ticagrelor would be advantageous. The pharmacodynamic effects of ticagrelor and a ticagrelor reversal agent are best evaluated using a panel of platelet function tests that have different sensitivities and methodologies and using a variety of agonists at different concentrations.

Purpose

In a first-in-human randomized, double-blind, placebo-controlled, healthy volunteer Phase 1 study, intravenous (IV) PB2452, a monoclonal antibody fragment that binds ticagrelor with high affinity, was evaluated as a ticagrelor reversal agent.

Methods

Platelet function was assessed using light transmission aggregometry (LTA) and 5 and 20 μM adenosine diphosphate (ADP), 1.6 mM arachidonic acid (AA), and 15 μM thrombin receptor agonist peptide (TRAP-6) as agonists. The VerifyNow P2Y12 cartridges, which assess whole blood platelet function, were evaluated as a point-of-care test. A modified vasodilator-stimulated phosphoprotein (VASP) ELISA was used to assess the extent of P2Y12 signaling. These assessments were performed 48 h prior to ticagrelor administration and at multiple time points up to 48 h after administration of PB2452 or placebo.

Results

64 subjects were randomized; 48 received PB2452 and 16 received placebo. After ticagrelor administration, LTA response to 20 μM ADP was inhibited by 87% compared to the pre-ticagrelor values. Platelet function as measured by the VerifyNow P2Y12 cartridge was completely inhibited (<10 platelet reactivity units [PRU]). The VASP platelet reactivity index (PRI) was inhibited by 82%. Ticagrelor reduced TRAP-6 induced LTA by 30% reflecting the effect of ADP on platelet aggregate stability. PB2452 administered as a 10 min IV bolus followed by 16 h infusion, significantly restored platelet function to >80% and >90% of baseline as measured by LTA using ADP and TRAP-6, respectively, to >180 PRU using VerifyNow, and to >90% PRI as measured by VASP. The VASP assay enabled batch analyses in a central laboratory, eliminating the need for special equipment on-site and reducing operator variability. When platelet function was assessed by VASP, PB2452 administration produced rapid ticagrelor reversal within 5 min consistent with restoration of P2Y12 signaling. Onset of reversal by all measurements occurred within 15 min of PB2452 administration and was sustained for 20–24 h.

Conclusions

PB2452 is a specific reversal agent for ticagrelor and produces a rapid and sustained reversal of ticagrelor inhibition of platelets. Utilizing multiple platelet function assays provided a broader understanding of the PB2452 pharmacodynamics in this first-in-human Phase 1 study.

Acknowledgement/Funding

PhaseBio Pharmaceuticals

Anticoagulation therapy patterns for acute treatment of venous thromboembolism in GARFIELD-VTE patients

BACKGROUND

Parenteral anticoagulants and vitamin K antagonists (VKAs) have constituted the cornerstone of venous thromboembolism (VTE) treatment. Meanwhile, direct oral anticoagulants (DOACs) provide physicians with an alternative. The Global Anticoagulant Registry in the FIELD (GARFIELD)-VTE observes real-world treatment practices.

OBJECTIVES

Describe initial anticoagulation (AC) treatment patterns in VTE patients who received parenteral AC, VKAs, and/or DOACs within ±30 days of diagnosis.

METHODS

VTE patients were categorized into parenteral AC only, parenteral AC with transition to VKA, VKA only, parenteral AC with transition to DOAC, and DOAC only.

RESULTS

A total of 9647 patients were initiated on AC treatment alone. 4781 (49.6%) patients received DOACs ± parenteral ACs; 3187 (33.0%), VKA ± parenteral ACs; and 1679 (17.4%) parenteral ACs alone. Rivaroxaban was the most frequently used DOAC (79.4%). DOACs were more frequently used in North America/Australia (58.1%), Europe (52.2%), and Asia (47.6%) than in Latin America (29.7%) and the Middle East/South Africa (32.5%). In patients with suspected VTE, most received parenteral AC monotherapy (67.7%). Patients with deep vein thrombosis were more likely to receive DOACs alone than those with pulmonary embolism with or without deep vein thrombosis (36.2% vs 25.9%). Active cancer patients received parenteral AC alone (58.9%), with 25.5% receiving DOAC ± parenteral AC and 12.8% parenteral AC and VKA. A total of 46.5% of pregnant patients received parenteral AC monotherapy, 34.0% were treated with VKA ± parenteral AC, and 19.5% received a DOAC (± parenteral AC).

CONCLUSION

AC treatment patterns vary by patient population, geographic region and site of VTE. Guidelines for AC therapy are not always adhered to.

Influence of model-predicted rivaroxaban exposure and patient characteristics on efficacy and safety outcomes in patients with acute coronary syndrome

Background:

This analysis aimed to evaluate the impact of rivaroxaban exposure and patient characteristics on efficacy and safety outcomes in patients with acute coronary syndrome (ACS) and to determine whether therapeutic drug monitoring might provide additional information regarding rivaroxaban dose, beyond what patient characteristics provide.

Methods:

A post hoc exposure–response analysis was conducted using data from the phase III ATLAS ACS 2 Thrombolysis in Myocardial Infarction (TIMI) 51 study, in which 15,526 randomized ACS patients received rivaroxaban (2.5 mg or 5 mg twice daily) or placebo for a mean of 13 months (maximum follow up: 31 months). A multivariate Cox model was used to correlate individual predicted rivaroxaban exposures and patient characteristics with time-to-event clinical outcomes.

Results:

For the incidence of myocardial infarction (MI), ischemic stroke, or nonhemorrhagic cardiovascular death, hazard ratios (HRs) for steady-state maximum plasma concentration (C_max) in the 5th and 95th percentiles versus the median were statistically significant but close to 1 for both rivaroxaban doses. For TIMI major bleeding events, a statistically significant association was observed with C_max [HR, 1.08; 95% CI, 1.06–1.11 (95th percentile versus median, 2.5 mg twice daily)], sex [HR, 0.56; 95% CI, 0.38–0.84 (female versus male)], and previous revascularization [HR, 0.62; 95% CI, 0.44–0.87 (no versus yes)].

Conclusions:

The shallow slopes of the exposure–response relationships and the lack of a clear therapeutic window render it unlikely that therapeutic drug monitoring in patients with ACS would provide additional information regarding rivaroxaban dose beyond that provided by patient characteristics.

Effect of Different Doses of Acetylsalicylic Acid on the Antithrombotic Activity of Clopidogrel in a Mouse Arterial Thrombosis Model

Objective- Dual-antiplatelet therapy with acetylsalicylic acid and a P2Y₁₂ antagonist, such as clopidogrel, is the standard of care for acute coronary syndromes. However, the drugs have divergent effects on the formation of cAMP, an inhibitory second messenger. Thus, by inhibiting the synthesis of prostacyclin, acetylsalicylic acid reduces cAMP formation, whereas clopidogrel potentiates it. Therefore, with higher doses of acetylsalicylic acid, the potentiation of cAMP production by clopidogrel may be attenuated, which could limit the antithrombotic potential of the drug combination. The purpose of this study was to examine this possibility in vivo. Approach and Results- Mice were given oral acetylsalicylic acid at varying doses, oral clopidogrel (5 mg/kg body weight), or both. At doses of 0.15 and 0.6 mg/kg, acetylsalicylic acid inhibited arachidonic acid-induced platelet aggregation, but only 0.6 mg/kg acetylsalicylic acid, or higher, decreased the plasma levels of 6-keto-prostaglandin-F_1α, the stable metabolite of prostacyclin. When given with clopidogrel, laser injury-induced arterial thrombi were significantly larger with the 0.6 mg/kg dose of acetylsalicylic acid than with the 0.15 mg/kg dose. Thrombi in mice treated with clopidogrel and the 0.15 mg/kg dose of acetylsalicylic acid were smaller than in mice treated with clopidogrel alone, suggesting that acetylsalicylic acid can add to the antithrombotic effect of clopidogrel but that higher doses of acetylsalicylic acid blunt the antithrombotic effect of clopidogrel. Conclusions- These findings support the use of lower, prostacyclin-preserving, doses of acetylsalicylic acid in conjunction with clopidogrel.