Evolving Treatments for Arterial and Venous Thrombosis: Role of the Direct Oral Anticoagulants

Direct Oral Anticoagulants in Older and Frail Patients with Atrial Fibrillation: A Decade of Experience

INTRODUCTION

Both the prevalence of atrial fibrillation (AF) and its subsequent use of direct oral anticoagulants (DOACs) are rapidly increasing in patients of older age. In the absence of contra-indications, guidelines advocate anticoagulation based on the CHA2DS2-VASc score for all AF patients aged 75 and above. However, some practitioners are hesitant to prescribe anticoagulants to older and frail patients due to perceived elevated bleeding risks. This review delves into the comparative treatment outcomes of DOACs versus vitamin K antagonists (VKAs) in older patients with AF, particularly focusing on those of advanced age, frailty, increased risk of falling, chronic kidney disease (CKD), or with a history of major bleeding. Additionally, considerations on the use of off-label DOAC doses, the role of left atrial appendage (LAA) closure and future developments in factor XIa-inhibitors will be discussed.

RESULTS

While strong evidence supports the use of DOACs in the vital older patients with nonvalvular AF, it remains scant in frail patient groups. There is some evidence from non-randomized studies suggesting that the effect of DOACs compared with VKAs is consistent between frail and nonfrail patients. However, recent findings from a single randomized trial showed increased bleeding risks but comparable thromboembolic outcomes in frail individuals switching from VKAs to DOACs. In patients with an increased risk of falling, data suggest no relevant interaction of increased risk of falling on the effectiveness and safety of DOACs compared with warfarin. Resuming oral anticoagulants in patients with Af after major bleeding seems to be beneficial. Off-label low-dose DOAC is often prescribed to patients who were underrepresented in larger randomized trails because of an elevated risk of bleeding or overexposure to DOACs, but its effect on clinical outcomes remains uncertain.

CONCLUSIONS

DOACs are the recommended oral anticoagulant for vital older patients with AF. The scarcity of data backing DOAC use in frail individuals, those with renal impairments, or significant bleeding history underscores the necessity for further investigation. However, existing evidence suggests at least similar effectiveness and safety and potential benefits for DOACs in these patient subsets. Therefore, there is no reason to suggest these patients should be treated differently than the established guidelines regarding anticoagulation.

Prescription and switching patterns of direct oral anticoagulants in patients with atrial fibrillation

Background

The patterns of direct oral anticoagulant (DOAC) selection and switching to a different oral anticoagulant (OAC) in patients with atrial fibrillation (AF) are unknown.

Objectives

To describe temporal patterns in first DOAC prescriptions, estimate the incidence, and identify predictors of switching to a different OAC within 1 year in OAC-naive AF patients.

Methods

In this retrospective cohort study, using a near-nationwide prescription registry (IQVIA, the Netherlands), we determined the number of patients per month initiated on each DOAC and identified predictors of switching within 1 year with robust Poisson regression.

Results

We included 94,874 patients. From November 2015 to November 2019, the monthly use of apixaban (n = 366 to n = 1066, +191%), rivaroxaban (n = 379 to n = 868, +129%), and edoxaban (n = 2 to n = 305, +15,150%) increased, whereas that of dabigatran decreased (n = 317 to n = 179, -44%). In the 66,090 patients with ≥1 year of available calendar time, 7% switched to a different OAC within 1 year. Strong predictors of switching to a different DOAC were using dabigatran (adjusted risk ratio [aRR], 3.33; 95% CI, 3.02-3.66) or edoxaban (aRR, 1.56; 95% CI, 1.34-1.82) rather than apixaban and using a standard DOAC dose (aRR, 2.54; 95% CI, 2.23-2.88). Strong predictors of switching to a vitamin K antagonist were using rivaroxaban (aRR, 1.36; 95% CI, 1.19-1.54 vs apixaban) and using a standard DOAC dose (aRR, 1.49; 95% CI, 1.26-1.77).

Conclusion

In the Netherlands, factor Xa inhibitors are increasingly being selected for OAC-naive AF patients. Seven percent of patients switch to a different OAC within 1 year, and the initial DOAC type and dose are strong predictors of switching.

Vascular fingerprint tool to identify patients with testicular cancer treated with cisplatin-based chemotherapy at high risk of early cardiovascular events

BACKGROUND

Patients with testicular cancer treated with chemotherapy have an increased risk of developing early cardiovascular events. Identification of patients with testicular cancer at a high risk of these events enables the development of preventative strategies. This study validates the vascular fingerprint tool to identify these patients.

PATIENTS AND METHODS

We carried out a multicenter prospective study in patients with metastatic testicular cancer [International Germ Cell Cancer Collaborative Group (IGCCCG) good or intermediate risk; retroperitoneal mass <5 cm]. In eligible patients, the vascular fingerprint was assessed before the start of cisplatin-based chemotherapy, which consists of five risk factors, namely, smoking, overweight (body mass index >25 kg/m2), hypertension (blood pressure >140/90 mmHg), dyslipidemia (fasting cholesterol >5.1 mmol/l or low-density lipoprotein-cholesterol >2.5 mmol/l), and diabetes mellitus (fasting glucose ≥7.0 mmol/l). The presence of three or more risk factors was defined as high-risk vascular fingerprints. A log-rank test was carried out with a cardiovascular event within 1 year after the start of chemotherapy as the primary endpoint.

RESULTS

A total of 196 patients with metastatic testicular cancer were included; 15 patients (8%) developed a cardiovascular event: 4 (2%) arterial events and 11 (6%) venous thrombotic events. Overall, 189 vascular fingerprint scores were available. Patients with a high-risk vascular fingerprint (62/189) had a higher risk of developing a cardiovascular event (hazard ratio 3.27, 95% confidence interval 1.16-9.18; log-rank: P = 0.017). Histological diagnosis, prognosis group, cumulative chemotherapy dose, and retroperitoneal mass size did not differ between patients with or without a cardiovascular event. All patients with an arterial event had a high-risk vascular fingerprint compared with 5/11 patients with a venous event. Overweight was more prevalent in patients with cardiovascular events (87% versus 59%; P = 0.037).

CONCLUSIONS

The vascular fingerprint is a validated tool to identify patients with testicular cancer at a high risk of developing early cardiovascular events. This tool can be used to develop preventative strategies with anticoagulant treatment.

IVC filter - assessing the readability and quality of patient information on the Internet

OBJECTIVE

The internet is an increasingly favorable source of information regarding health-related issues. The aim of this study is to apply appropriate evaluation tools to assess the evidence available online about inferior vena cava (IVC) filters with a focus on quality and readability.

METHODS

A search was performed during December 2022 using three popular search engines, namely Google, Yahoo, and Bing. Websites were categorized into academic, physician, commercial, and unspecified websites according to their content. Information quality was determined using Journal of the American Medical Association (JAMA) criteria, the DISCERN scoring tool, and whether a Health On the Net Foundation certification (HONcode) seal was present. Readability was established using the Flesch Reading Ease Score (FRES) and Flesch-Kincaid Grade Level (FKGL). Statistical significance was accepted as P < .05.

RESULTS

In total, 110 websites were included in our study. The majority of websites were categorized as commercial (25%), followed by hospital (24%), academic (21%), unspecified (16%), and physician (14%). Average scores for all websites using JAMA and DISCERN were 1.93 ± 1.19 (median, 1.5; range, 0-4) and 45.20 ± 12.58 (median, 45.5; range, 21-75), respectively. The highest JAMA mean score of 3.07 ± 1.16 was allocated to physician websites, and the highest DISCERN mean score of 52.85 ± 12.66 was allocated to hospital websites. The HONcode seal appeared on two of the selected websites. Physician, hospital, and unspecified websites had a significantly higher mean JAMA score than academic and commercial websites (all with P < .001). Hospital websites had a significantly higher mean DISCERN score than academic (P = .007), commercial (P < .001), and unspecified websites (P = .017). Readability evaluation generated a mean FRES score of 51.57 ±12.04, which represented a 10th to 12th grade reading level and a mean FKGL score of 8.20 ± 1.70, which represented an 8th to 10th grade reading level. Only 12 sources were found to meet the ≤6th grade target reading level. No significant correlation was found between overall DISCERN score and overall FRES score.

CONCLUSIONS

The study results demonstrate that the quality of online information about IVC filters is suboptimal, and academic and commercial websites, in particular, must enhance their content quality regarding the use of IVC filters. Considering the discontinuation of the HONcode as a standardized quality assessment marker, it is recommended that a similar certification tool be developed and implemented for the accreditation of patient information online.

New Therapeutic Targets for the Prevention and Treatment of Venous Thromboembolism With a Focus on Factor XI Inhibitors

FXI (factor XI) and FXII (factor XII) have emerged as targets for new anticoagulants that have the potential to be both more efficacious and safer than the currently available direct oral anticoagulants for the prevention and treatment of venous thromboembolism. In this review, we discuss the role of FXI and FXII in the pathogenesis of venous thromboembolism, explain why FXI is a better target, and explain why FXI inhibitors have potential advantages over currently available anticoagulants. Finally, we describe the FXI inhibitors under development and discuss their potential to address unmet needs in venous thromboembolism management.

The Safety, Pharmacokinetics, and Pharmacodynamics of SHR2285, an Oral Small Molecule Factor XIa Inhibitor, in Healthy Chinese Volunteers

BACKGROUND AND OBJECTIVE

There is an unmet need for a safer anticoagulant since bleeding remains a concern with currently approved anticoagulants. Coagulation factor XI (FXI) is an attractive anticoagulant drug target with limited a role in physiological hemostasis. The objective of this study was to evaluate the safety, pharmacokinetics, and pharmacodynamics of SHR2285, a novel small molecule FXIa inhibitor, in healthy Chinese volunteers.

METHODS

The study consisted of single ascending doses part (part 1: 25-600 mg) and multiple ascending doses part (part 2: 100, 200, 300, and 400 mg). In both parts, subjects were randomized in a 3:1 ratio to receive SHR2285 or placebo orally. Blood, urine and feces samples were collected to describe its pharmacokinetic and pharmacodynamic profile.

RESULTS

In total, 103 healthy volunteers completed the study. SHR2285 was well tolerated. SHR2285 was absorbed rapidly with median time to maximum plasma concentration (T_max) of 1.50 to 3.00 h. The geometric median half-life (t_1/2) of SHR2285 varied from 8.74 to 12.1 h across 25-600 mg single dose. Total systemic exposure of metabolite SHR164471 was approximately 1.77- to 3.61-fold that of the parent drug. The plasma concentration of SHR2285 and SHR164471 reached steady state by the morning of Day 7, with low accumulation ratio (0.956-1.20 and 1.18-1.56, respectively). The increase in pharmacokinetic exposure of SHR2285 and SHR164471 was less than dose proportional. Food has minimal effect on the pharmacokinetics of SHR2285 and SHR164471. SHR2285 produced an exposure-dependent prolongation of activated partial thromboplastin time (APTT) and a decrease in FXI activity. The maximum FXI activity inhibition rate (geometric mean) at steady state was 73.27%, 85.58%, 87.77% and 86.27% for 100-400 mg, respectively.

CONCLUSIONS

SHR2285 was generally safe and well tolerated in healthy subjects across a wide range of doses. SHR2285 exhibited a predictable pharmacokinetic profile and an exposure-related pharmacodynamic profile.

CLINICALTRIALS

gov Identifier NCT04472819; registered on July 15, 2020.

Profibrinolytic effects of rivaroxaban are mediated by thrombin-activatable fibrinolysis inhibitor and are attenuated by a naturally occurring stabilizing mutation in enzyme

Rivaroxaban is a direct factor Xa inhibitor, recently implemented as a favorable alternative to warfarin in anticoagulation therapy. Rivaroxaban effectively reduces thrombin generation, which plays a major role in the activation of thrombin activatable fibrinolysis inhibitor (TAFI) to TAFIa. Based on the antifibrinolytic role of TAFIa, we hypothesized that rivaroxaban would consequently induce more rapid clot lysis. In vitro clot lysis assays were used to explore this hypothesis and additionally determine the effects of varying TAFI levels and a stabilizing Thr325Ile polymorphism (rs1926447) in the TAFI protein on the effects of rivaroxaban. Rivaroxaban was shown to decrease thrombin generation, resulting in less TAFI activation, thus enhancing lysis. These effects were also shown to be less substantial in the presence of greater TAFI levels or the more stable Ile325 enzyme. These findings suggest a role for TAFI levels and the Thr325Ile polymorphism in the pharmacodynamics and pharmacogenomics of rivaroxaban.

Impact of venous thromboembolism on incidence of arterial thromboembolism - An analysis of German outpatient claims data

BACKGROUND

Venous thromboembolism (VTE) and arterial thromboembolism (ATE) are considered as two separate disease-entities. In recent years, studies have reported clear associations between VTE and atherosclerosis. We aimed to evaluate the long-term risk of ATE in VTE patients in comparison to controls without VTE.

METHODS

Nationwide outpatient claims data of all inhabitants with statutory health insurance in Germany were used for secondary data analysis between the years 2011 and 2020. Patients treated in 2013 were stratified by VTE event, and groups were 1:2-matched by age and sex. The hazard for an ATE event in a 5-year follow-up period between patients with and without VTE was calculated with multivariable Cox regression adjusted for age, sex, cardiovascular risk factors, and comorbidities.

RESULTS

Of 69,699,277 individuals treated in the year 2013 by German physicians in outpatient care, in total 686,382 individuals (age 59.8 ± 17.5 years, 65.4 % females) were included comprising 228,794 patients with VTE and 457,588 controls without VTE. VTE patients more often had cardiovascular risk factors (81.6 % vs. 62.2 %) and traditional VTE risk factors. The occurrence of ATE events during follow-up was 1.8 %-points higher in VTE patients in comparison to the controls (9.7 % vs. 7.9 %). VTE events were independently associated with increased occurrence of ATE events within follow-up (HR_adjusted 1.19 [99%CI 1.16-1.23], p < 0.0001).

CONCLUSIONS

Patients with a VTE event have an increased long-term risk for subsequent arterial cardiovascular events. Large prospective cohorts are needed to identify patient subgroups with a very high ATE risk after VTE.

Platelet-Neutrophil Crosstalk in Thrombosis

Platelets are essential for the formation of a haemostatic plug to prevent bleeding, while neutrophils are the guardians of our immune defences against invading pathogens. The interplay between platelets and innate immunity, and subsequent triggering of the activation of coagulation is part of the host system to prevent systemic spread of pathogen in the blood stream. Aberrant immunothrombosis and excessive inflammation can however, contribute to the thrombotic burden observed in many cardiovascular diseases. In this review, we highlight how platelets and neutrophils interact with each other and how their crosstalk is central to both arterial and venous thrombosis and in COVID-19. While targeting platelets and coagulation enables efficient antithrombotic treatments, they are often accompanied with a bleeding risk. We also discuss how novel approaches to reduce platelet-mediated recruitment of neutrophils could represent promising therapies to treat thrombosis without affecting haemostasis.

Fibrinogen, Coagulation, and Ageing

The World Health Organization estimates that the world's population over 60 years of age will nearly double in the next 30 years. This change imposes increasing demands on health and social services with increased disease burden in older people, hereafter defined as people aged 60 years or more. An older population will have a greater incidence of cardiovascular disease partly due to higher levels of blood fibrinogen, increased levels of some coagulation factors, and increased platelet activity. These factors lead to a hypercoagulable state which can alter haemostasis, causing an imbalance in appropriate coagulation, which plays a crucial role in the development of cardiovascular diseases. These changes in haemostasis are not only affected by age but also by gender and the effects of hormones, or lack thereof in menopause for older females, ethnicity, other comorbidities, medication interactions, and overall health as we age. Another confounding factor is how we measure fibrinogen and coagulation through laboratory and point-of-care testing and how our decision-making on disease and treatment (including anticoagulation) is managed. It is known throughout life that in normal healthy individuals the levels of fibrinogen and coagulation factors change, however, reference intervals to guide diagnosis and management are based on only two life stages, paediatric, and adult ranges. There are no specific diagnostic guidelines based on reference intervals for an older population. How ageing relates to alterations in haemostasis and the impact of the disease will be discussed in this chapter. Along with the effect of anticoagulation, laboratory testing of fibrinogen and coagulation, future directions, and implications will be presented.

Impact of the COVID-19 pandemic on England's national prescriptions of oral vitamin K antagonist (VKA) and direct-acting oral anticoagulants (DOACs): an interrupted time series analysis (January 2019-February 2021)

BACKGROUND

Direct-acting oral anticoagulants (DOACs) were developed as an alternative to warfarin to treat and prevent thromboembolism, including stroke prevention in non-valvular atrial fibrillation patients. The COVID-19 pandemic could increase the risk of stroke and/or the risk of bleeding in patients due to nonadherence or sub/supra-optimal dosing.

OBJECTIVE

To investigate DOAC prescription trends in England's community settings during the complete first wave of COVID-19 pandemic.

METHODS

Descriptive and interrupted time series (ITS) analyses were conducted to examine the prescription patterns of DOACs (dabigatran, rivaroxaban, apixaban and edoxaban) and warfarin for primary care patients in the English Prescribing Dataset from January 2019 to February 2021, with March 2020 as the cut-off point.

RESULTS

A 19% increase in mean DOAC's accompanied with 20% warfarin prescriptions decline was observed. ITS modelling showed an increase in DOAC prescription volume in March 2020 (+7 million items, p = 0.008). The pre-existing upward trend in DOAC prescriptions slowed during the period (-427,000 items, p = 0.007). Apixaban was the most frequently used DOAC and had the largest step-change in March 2020 (+5 million items, p = 0.010). The mean monthly combined cost of DOACs and warfarin was higher during the period. DOAC prescription trends were consistent across England's regions. Conclusion: The overall oral anticoagulants use in this period was lower than expected, indicating a medical needs gap, possibly due to adherence issues. The potential clinical and logistical consequences warrant further study to identify contributing factors and mitigate avoidable risks.

Drug-Related Problems and Factors Involved in the Imbalance of Oral Anticoagulants in Lebanese Patients: A Cross-Sectional Study

The goal of this study was to identify drug-related problems (DRPs) and the factors involved in the imbalance of new oral anticoagulants (NOACs) and vitamin K antagonists in a Lebanese adult population with cardiovascular diseases. An imbalance in the hemostatic systems between procoagulant and anticoagulant factors in circulating blood produces either hemorrhagic or thrombotic conditions. A prospective cross-sectional study was conducted during 5 months in a teaching hospital. All patients at least 18 years of age taking oral anticoagulants were included in the study. A standardized questionnaire was used, and information was obtained from the patients’ profiles and electronic medical records. DRPs were identified and categorized according to the Pharmaceutical Care Network Europe classification system. A total of 258 patients were included. The overall prevalence of DRPs was 87.2%; the highest prevalence was observed in patients taking acenocoumarol (96.0%), in contrast to 76.7% and 59.0% in patients taking dabigatran and rivaroxaban, respectively. Drug interaction was the most frequent DRP (83.3%), followed by inappropriate monitoring (42.6%) and excessive dose (26.7%). Having renal disease, and taking proton-pump inhibitors or nonsteroidal anti-inflammatory drugs were among the factors affecting the international normalized ratio (INR) range (adjusted odds ratio [ORa] = 2.513, 95% confidence interval [CI] 1.238, 5.101; ORa = 2.487, 95% CI 1.139, 5.430 and ORa = 2.114, 95% CI 1.043, 4.286, respectively), whereas smoking and renal disease significantly affected activated partial thromboplastin time (aPTT) (ORa = 8.325, 95% CI 1.577, 43.965 and ORa = 6.922, 95% CI 1.471, 32.570, respectively). Patients taking NOACs had greater aPTT control and fewer DRPs, with a wide therapeutic index enabling administration of fixed doses.

Assessment of treatment patterns and patient awareness in atrial fibrillation patients using non-vitamin K antagonist oral anticoagulants (ASPECT-NOAC)

Background and Aim

Despite the advances in oral anticoagulation with NOACs, careful patient and dose selection is required with NOAC therapy. Our study aimed to assess treatment patterns of NOACs in AF along with patients’ continuity to NOAC treatments in first year, and their knowledge level of AF and NOAC treatment.

Methods

ASPECT-NOAC was designed as an observational, prospective, and multicenter study. AF patients who were prescribed NOACs within last four months were recruited from 34 outpatient cardiology clinics covering all geographic regions of Turkey. Baseline data were collected initially whereas patient awareness was evaluated at 3 to 4 weeks. Final study visit was performed at 12 months.

Results

In total, 991 patients were included to the study. Mean ± standard deviation of age was 69.4 ± 10.2 years and 53.0% of patients were female. Mean duration from AF diagnosis was 24.9 ± 50.9 months. Mean CHA₂DS₂-VASc and HAS-BLED scores were 3.1 ± 1.5 and 1.6 ± 1.1, respectively. AF disease and NOAC treatment knowledge levels were found to be 48.9 ± 23.1% and 73.0 ± 19.3%, respectively. Among reduced dose users 71.4% of patients were prescribed inappropriate reduced doses. Through the study follow-up, 32 patients (3.2%) deceased and NOAC therapy was discontinued in 74 patients (8.7%).

Conclusion

AF patients who recently started NOAC treatment in Turkey were found to have variable knowledge about their disease and anticoagulation treatment. It was observed that most of the patients continued the NOAC treatment throughout the study. Reduced dosing of NOACs was common, which was associated with higher baseline risk for bleeding as well as stroke.

COVID-19 is associated with higher risk of venous thrombosis, but not arterial thrombosis, compared with influenza: Insights from a large US cohort

Introduction

Infection with SARS-CoV-2 is typically compared with influenza to contextualize its health risks. SARS-CoV-2 has been linked with coagulation disturbances including arterial thrombosis, leading to considerable interest in antithrombotic therapy for Coronavirus Disease 2019 (COVID-19). However, the independent thromboembolic risk of SARS-CoV-2 infection compared with influenza remains incompletely understood. We evaluated the adjusted risks of thromboembolic events after a diagnosis of COVID-19 compared with influenza in a large retrospective cohort.

Methods

We used a US-based electronic health record (EHR) dataset linked with insurance claims to identify adults diagnosed with COVID-19 between April 1, 2020 and October 31, 2020. We identified influenza patients diagnosed between October 1, 2018 and April 31, 2019. Primary outcomes [venous composite of pulmonary embolism (PE) and acute deep vein thrombosis (DVT); arterial composite of ischemic stroke and myocardial infarction (MI)] and secondary outcomes were assessed 90 days post-diagnosis. Propensity scores (PS) were calculated using demographic, clinical, and medication variables. PS-adjusted hazard ratios (HRs) were calculated using Cox proportional hazards regression.

Results

There were 417,975 COVID-19 patients (median age 57y, 61% women), and 345,934 influenza patients (median age 47y, 66% women). Compared with influenza, patients with COVID-19 had higher venous thromboembolic risk (HR 1.53, 95% CI 1.38–1.70), but not arterial thromboembolic risk (HR 1.02, 95% CI 0.95–1.10). Secondary analyses demonstrated similar risk for ischemic stroke (HR 1.11, 95% CI 0.98–1.25) and MI (HR 0.93, 95% CI 0.85–1.03) and higher risk for DVT (HR 1.36, 95% CI 1.19–1.56) and PE (HR 1.82, 95% CI 1.57–2.10) in patients with COVID-19.

Conclusion

In a large retrospective US cohort, COVID-19 was independently associated with higher 90-day risk for venous thrombosis, but not arterial thrombosis, as compared with influenza. These findings may inform crucial knowledge gaps regarding the specific thromboembolic risks of COVID-19.

Can a Single Measurement of Apixaban Levels Identify Patients at Risk of Overexposure? A Prospective Cohort Study

Background Patients with atrial fibrillation (AF) are frequently treated with apixaban 2.5-mg twice daily (BID) off-label, presumably to reduce the bleeding risk. However, this approach has the potential to increase the risk of ischemic stroke. If a single measurement could reliably identify patients with high drug levels, the increased stroke risk may be mitigated by confining off-label dose reduction to such patients.

Objectives This study aimed to determine whether a single high apixaban level is predictive of a similarly high level when the test is repeated in 2 months.

Methods In this prospective cohort study of clinic patients receiving apixaban 5-mg BID for AF or venous thromboembolism, peak and trough apixaban levels were measured using the STA-Liquid anti-Xa assay at baseline and 2 months. We calculated the proportions of patients with levels that remained in the upper quintile.

Results Of 100 enrolled patients, 82 came for a second visit, 55 of whom were treated with apixaban 5-mg BID. Seven (63.6%, 95% confidence interval [CI]: 35.4–84.8%) and nine (81.8%, 95% CI: 52.3–94.9%) of 11 patients with a baseline trough and peak level in the upper quintile, respectively, had a subsequent level that remained within this range. Only one (9.1%, 95% CI: 1.6–37.7%) patient had a subsequent level that fell just lower than the median.

Conclusion The trough and peak levels of apixaban in patients who have a high level on a single occasion, usually remain high when the assay is repeated in 2 months. Accordingly, the finding of a high apixaban level in patients deemed to be at high risk of bleeding, allows physicians contemplating off-label use of the 2.5-mg BID dose to limit its use to selected patients who are less likely to be exposed to an increased risk of thrombosis.

A rare case of marijuana associated with ascending aorta thrombosis complicated with stroke and bilateral renal infarcts

Ascending aortic is an uncommon site for arterial thrombosis and ascending aortic thrombosis is a very rare phenomenon with a high fatality rate. Marijuana is the most commonly used psychoactive drug in the United States and a few cases have been reported on the association of marijuana with vascular thromboembolism. However, the pathophysiology and exact mechanism are still not well studied. Herein, we present a case of a 44-year-old female with active marijuana use presented with ascending aortic thrombus associated with acute arterial occlusion of the right vertebral artery and bilateral renal artery. The unique part of this case is that the patient did not have the classical risk factors for vascular thromboembolic disease. The only risk factor was marijuana smoking. To our best knowledge, this is one of the unique cases of marijuana-associated with ascending aorta thrombosis.

Anticoagulation Treatment in Venous Thromboembolism: Options and Optimal Duration

Venous thromboembolism (VTE), clinically presenting as deep-vein thrombosis (DVT) or pulmonary embolism (PE), constitutes a major global healthcare concern with severe complications, long-term morbidity and mortality. Although several clinical, genetic and acquired risk factors for VTE have been identified, the molecular pathophysiology and mechanisms of disease progression remain poorly understood. Anticoagulation has been the cornerstone of therapy for decades, but there still are uncertainties regarding primary and secondary VTE prevention, as well as optimal therapy duration. In this review we discuss the role of factor Xa in coagulation cascade and the different choices of anticoagulation therapy based on patients' predisposing risk factors and risk of event recurrence. Further, we compare newer agents to traditional anticoagulation treatment, based on most recent studies and guidelines.

Venous Thromboembolism for the Practicing Cardiologist

Venous thromboembolism (VTE), encompassing pulmonary embolism (PE) and deep vein thrombosis (DVT), is encountered commonly. Acute PE may present as a high-risk cardiovascular emergency, and acute DVT can cause acute and chronic vascular complications. The goal of this review is to ensure that cardiologists are comfortable managing VTE-including risk stratification, anticoagulation therapy, and familiarity with primary reperfusion therapy. Clinical assessment and determination of degree of right ventricular dysfunction are critical in initial risk stratification of PE and determination of parenteral versus oral anticoagulation therapy. Direct oral anticoagulants have emerged as preferred first-line oral anticoagulation strategy in VTE scenarios.

Venous thromboembolism associated with central venous catheters in patients with cancer: From pathophysiology to thromboprophylaxis, areas for future studies

Symptomatic catheter related thrombosis (CRT) occurs in 4%-8% of cancer patients. The mean incidence of CRT, detected either by echography or Doppler ranges between 12 and 14% with a high negative predictive value of about 95%, allowing the subsequent occurrence of CRT (symptomatic and asymptomatic) to be safely excluded. Despite its frequency and its medico-economic consequences, no thromboprophylaxis has been validated to date. In most patients, CRT occurs immediately after catheter insertion, most often within the first week and almost all within the first month after insertion. Meta analyses show a reduction of asymptomatic and symptomatic CRT incidence by about 55%-60% using either vitamin K antagonists or low molecular weight heparins without an increased risk of major bleeding. This pharmacological prophylaxis is only effective when started before the central venous catheter insertion at prophylactic doses and thereafter continued at subtherapeutic doses. Since no population at high risk of CRT has been identified, this review focuses on pathophysiology, epidemiology and clinical supportive data that could lead to a new CRT prophylaxis strategy.

Thromboembolism, Bleeding, and Mortality Incidence of Direct Oral Anticoagulants Versus Warfarin Postbariatric Surgery

BACKGROUND

There is no randomized controlled trial comparing direct oral anticoagulants (DOACs) and warfarin following bariatric surgery to date. The mortality, thromboembolism, and bleeding risk of DOACs in comparison with warfarin following bariatric surgery remains unclear. We aimed to provide a clinical comparison between DOACs and warfarin for these 3 prespecified outcomes.

METHODS

A systematic literature search was performed on November 10, 2019, using PubMed, Embase, clinicaltrial.gov, and Cochrane databases. Studies with adult patients who were on either warfarin or DOACs following bariatric surgery and reported the incidence of thromboembolism, bleeding, or mortality were included. Pooled incidence for these prespecified outcomes and its 95% confidence interval (CI) were calculated for each drug separately using the random-effects model, along with a nonadjusted P value comparing the 2 subgroups.

RESULTS

A total of 11 studies (805 patients) were included. Comparing DOACs to warfarin, the following pooled incidences were observed for mortality (DOACs: 3.0%; 95% CI 0.4%-18.6% versus warfarin: 1.5%; 95% CI 0.8%-2.9%; P value comparing the 2 subgroups = .38), thromboembolism (DOACs: 4.9%; 95% CI 1%-21.1% versus warfarin: 1.5%; 95% CI 0.8%-2.9%; P value = .18), and bleeding (DOACs: 3.9%; 95% CI 0.7%-18.2% versus warfarin: 11.3%; 95% CI 5.7%-21.4%; P value = .23).

CONCLUSION

The results of our meta-analysis remain hypothesis-generating, providing rationale for future randomized controlled trial design or well-designed comparative observational studies. Currently, it does not support the change in the current recommendation from warfarin to DOACs following bariatric surgery.

COVID-19 is associated with higher risk of venous thrombosis, but not arterial thrombosis, compared with influenza: Insights from a large US cohort

Introduction

Infection with SARS-CoV-2 is typically compared with influenza to contextualize its health risks. SARS-CoV-2 has been linked with coagulation disturbances including arterial thrombosis, leading to considerable interest in antithrombotic therapy for Coronavirus Disease 2019 (COVID-19). However, the independent thromboembolic risk of SARS-CoV-2 infection compared with influenza remains incompletely understood. We evaluated the adjusted risks of thromboembolic events after a diagnosis of COVID-19 compared with influenza in a large retrospective cohort.

Methods

We used a US-based electronic health record (EHR) dataset linked with insurance claims to identify adults diagnosed with COVID-19 between April 1, 2020 and October 31, 2020. We identified influenza patients diagnosed between October 1, 2018 and April 31, 2019. Primary outcomes [venous composite of pulmonary embolism (PE) and acute deep vein thrombosis (DVT); arterial composite of ischemic stroke and myocardial infarction (MI)] and secondary outcomes were assessed 90 days post-diagnosis. Propensity scores (PS) were calculated using demographic, clinical, and medication variables. PS-adjusted hazard ratios (HRs) were calculated using Cox proportional hazards regression.

Results

There were 417,975 COVID-19 patients (median age 57y, 61% women), and 345,934 influenza patients (median age 47y, 66% women). Compared with influenza, patients with COVID-19 had higher venous thromboembolic risk (HR 1.53, 95% CI 1.38–1.70), but not arterial thromboembolic risk (HR 1.02, 95% CI 0.95–1.10). Secondary analyses demonstrated similar risk for ischemic stroke (HR 1.11, 95% CI 0.98–1.25) and MI (HR 0.93, 95% CI 0.85–1.03) and higher risk for DVT (HR 1.36, 95% CI 1.19–1.56) and PE (HR 1.82, 95% CI 1.57–2.10) in patients with COVID-19.

Conclusion

In a large retrospective US cohort, COVID-19 was independently associated with higher 90-day risk for venous thrombosis, but not arterial thrombosis, as compared with influenza. These findings may inform crucial knowledge gaps regarding the specific thromboembolic risks of COVID-19.

ROTEM Testing for Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs) are increasingly used worldwide for the prevention of stroke in patients with atrial fibrillation and to prevent or treat venous thromboembolism. In situations such as serious bleeding, the need for urgent surgery/intervention or the management of a thromboembolic event, the laboratory measurement of DOACs levels or anticoagulant activity may be required. Rotational thromboelastometry (ROTEM) is a viscoelastic hemostatic assay (VHA) which has been used in emergencies (trauma and obstetrics), and surgical procedures (cardiac surgery and liver transplants), but experience with this assay in DOACs-treated patients is still limited. This article reviews the use of ROTEM in the setting of DOACs therapy, focusing on DOACs-associated bleeding and the use of this VHA for the management of reversal strategies for DOACs-associated anticoagulation.

A significant improvement of thromboses treated by a new oral anticoagulant in an 11-year-old girl with systemic lupus erythematosus associated antiphospholipid syndrome: A case report

Pediatric venous thrombosis is associated with a variety of chronic diseases. Antiphospholipid syndrome (APS) is one of them and is commonly related to systemic lupus erythematosus (SLE). Warfarin is the mainstream of anticoagulation treatment in pediatric APS currently but it needs close monitoring and frequent dose adjustment. New oral anticoagulants (NOAC) is one of the innovative options in recent years but there is a lack of report in secondary prevention of deep vein thrombosis (DVT), especially pediatric APS. Herein we reported the significant therapeutic effect of edoxaban in a 11-year-old girl of newly diagnosed SLE and APS, who had deep vein thrombosis as the initial presentation.

Antithrombotics and new interventions for venous thromboembolism: Exploring possibilities beyond factor IIa and factor Xa inhibition

Direct oral anti-activated factor X and antithrombin agents have largely replaced vitamin K antagonists as the standard of care in treatment of venous thromboembolism. However, gaps in efficacy and safety persist, notably in end-stage renal disease, implantable heart valves or assist devices, extracorporeal support of the circulation, and antiphospholipid syndrome. Inhibition of coagulation factor XI (FXI) emerges as a promising new therapeutic target. Antisense oligonucleotides offer potential advantages as a prophylactic or therapeutic modality, with one dose-finding trial in orthopedic surgery already published. In addition, monoclonal antibodies blocking activation and/or activity of activated factor XI are investigated, as are small-molecule inhibitors with rapid offset of action. Further potential targets include upstream components of the contact pathway such as factor XII, polyphosphates, or kallikrein. Finally, catheter-directed, pharmacomechanical antithrombotic strategies have been developed for high- and intermediate-risk pulmonary embolism, and large randomized trials aiming to validate their efficacy, safety, and prognostic impact are about to start.

Synthesis and Bioactivities of Marine Pyran-Isoindolone Derivatives as Potential Antithrombotic Agents

2,5-Bis-[8-(4,8-dimethyl-nona-3,7-dienyl)-5,7-dihydroxy-8-methyl-3-keto-1,2,7,8-teraahydro-6H-pyran[a]isoindol-2-yl]-pentanoic acid (FGFC1) is a marine pyran-isoindolone derivative isolated from a rare marine microorganism Stachybotrys longispora FG216, which showed moderate antithrombotic(fibrinolytic) activity. To further enhance its antithrombotic effect, a series of new FGFC1 derivatives (F1-F7) were synthesized via chemical modification at C-2 and C-2' phenol groups moieties and C-1″ carboxyl group. Their fibrinolytic activities in vitro were evaluated. Among the derivatives, F1-F4 and F6 showed significant fibrinolytic activities with EC50 of 59.7, 87.1, 66.6, 82.8, and 42.3 μM, respectively, via enhancement of urokinase activity. Notably, derivative F6 presented the most remarkable fibrinolytic activity (2.72-fold than that of FGFC1). Furthermore, the cytotoxicity of derivative F6 was tested as well as expression of Fas/Apo-1 and IL-1 on HeLa cells. The results showed that, compared to FGFC1, derivative F6 possessed moderate cytotoxicity and apoptotic effect on HeLa cells (statistical significance p > 0.1), making F6 a potential antithrombotic agent towards clinical application.

Confocal Blood Flow Videomicroscopy of Thrombus Formation over Human Arteries and Local Targeting of P2X7

Atherothrombosis exposes vascular components to blood. Currently, new antithrombotic therapies are emerging. Herein we investigated thrombogenesis of human arteries with/without atherosclerosis, and the interaction of coagulation and vascular components, we and explored the anti-thrombogenic efficacy of blockade of the P2X purinoceptor 7 (P2X7). A confocal blood flow videomicroscopy system was performed on cryosections of internal mammary artery (IMA) or carotid plaque (CPL) determining/localizing platelets and fibrin. Blood from healthy donors elicited thrombi over arterial layers. Confocal microscopy associated thrombus with tissue presence of collagen type I, laminin, fibrin(ogen) and tissue factor (TF). The addition of antibodies blocking TF (aTF) or factor XI (aFXI) to blood significantly reduced fibrin deposition, variable platelet aggregation and aTF + aFXI almost abolished thrombus formation, showing synergy between coagulation pathways. A scarce effect of aTF over sub-endothelial regions, more abundant in tissue TF and bundles of laminin and collagen type I than deep intima, may suggest tissue thrombogenicity as molecular structure-related. Consistently with TF-related vascular function and expression of P2X7, the sections from CPL but not IMA tissue cultures pre-treated with the P2X7 antagonist A740003 demonstrated poor thrombogenesis in flow experiments. These data hint to local targeting studies on P2X7 modulation for atherothrombosis prevention/therapy.

Natural IgM antibodies inhibit microvesicle-driven coagulation and thrombosis

Thrombosis and its associated complications are a major cause of morbidity and mortality worldwide. Microvesicles (MVs), a class of extracellular vesicles, are increasingly recognized as mediators of coagulation and biomarkers of thrombotic risk. Thus, identifying factors targeting MV-driven coagulation may help in the development of novel antithrombotic treatments. We have previously identified a subset of circulating MVs that is characterized by the presence of oxidation-specific epitopes and bound by natural immunoglobulin M (IgM) antibodies targeting these structures. This study investigated whether natural IgM antibodies, which are known to have important anti-inflammatory housekeeping functions, inhibit the procoagulatory properties of MVs. We found that the extent of plasma coagulation is inversely associated with the levels of both free and MV-bound endogenous IgM. Moreover, the oxidation epitope-specific natural IgM antibody LR04, which recognizes malondialdehyde adducts, reduced MV-dependent plasmatic coagulation and whole blood clotting without affecting thrombocyte aggregation. Intravenous injection of LR04 protected mice from MV-induced pulmonary thrombosis. Of note, LR04 competed the binding of coagulation factor X/Xa to MVs, providing a mechanistic explanation for its anticoagulatory effect. Thus, our data identify natural IgM antibodies as hitherto unknown modulators of MV-induced coagulation in vitro and in vivo and their prognostic and therapeutic potential in the management of thrombosis.

Severe acute respiratory syndrome coronavirus 2-induced acute aortic occlusion: a case report

Background

Severe acute respiratory syndrome coronavirus 2 infection can lead to a constellation of viral and immune symptoms called coronavirus disease 2019. Emerging literature increasingly supports the premise that severe acute respiratory syndrome coronavirus 2 promotes a prothrombotic milieu. However, to date there have been no reports of acute aortic occlusion, itself a rare phenomenon. We report a case of fatal acute aortic occlusion in a patient with coronavirus disease 2019.

Case report

A 59-year-old Caucasian male with past medical history of peripheral vascular disease presented to the emergency department for evaluation of shortness of breath, fevers, and dry cough. His symptoms started 5–7 days prior to the emergency department visit, and he received antibiotics in the outpatient setting without any effect. He was found to be febrile, tachypneic, and hypoxemic. He was placed on supplemental oxygen via a non-rebreather mask. Chest X-ray showed multifocal opacifications. Intravenous antibiotics for possible pneumonia were initiated. Hydroxychloroquine was initiated to cover possible coronavirus disease 2019 pneumonia. During the hospitalization, the patient became progressively hypoxemic, for which he was placed on bilevel positive airway pressure. D-dimer, ferritin, lactate dehydrogenase, and C-reactive protein were all elevated. Severe acute respiratory syndrome coronavirus 2 reverse transcription polymerase chain reaction was positive. On day 3, the patient was upgraded to the intensive care unit. Soon after he was intubated, he developed a mottled appearance of skin, which extended from his bilateral feet up to the level of the subumbilical plane. Bedside ultrasound revealed an absence of flow from the mid-aorta to both common iliac arteries. The patient was evaluated emergently by vascular surgery. After a discussion with the family, it was decided to proceed with comfort-directed care, and the patient died later that day.

Discussion

Viral infections have been identified as a source of prothrombotic states due to direct injury of vascular tissue and inflammatory cascades. Severe acute respiratory syndrome coronavirus 2 appears to follow a similar pattern, with numerous institutions identifying elevated levels of thrombotic complications. We believe that healthcare providers should be aware of both venous and arterial thrombotic complications associated with coronavirus disease 2019, including possible fatal outcome.

Trial of Rivaroxaban in AntiPhospholipid Syndrome (TRAPS): Two-year outcomes after the study closure

BACKGROUND

Trial of Rivaroxaban in AntiPhospholipid Syndrome was a prospective randomized, open-label, noninferiority study conducted in 14 centers in Italy. Rivaroxaban was compared with warfarin for the prevention of thromboembolic events, major bleeding, and vascular death in high-risk, triple-positive patients with antiphospholipid syndrome.

OBJECTIVE

The aim of this paper is to report the events during the 2-year follow-up after the study closure.

METHODS

On January 28, 2018, the trial was prematurely stopped by adjudication and safety committee for an excess of events in the rivaroxaban group. Randomized patients were advised on trial results and those randomized to rivaroxaban were solicited to switch to warfarin. All 14 participating centers were asked and accepted to follow their patients for clinical events. This report describes the rate of events that occurred between January 28, 2018, and January 28, 2020.

RESULTS

Of 120 randomized patients, 115 were available for follow-up. Outcome events were two in six (33.3%) patients who remained on direct oral anticoagulants (DOACs) and six in 109 (5.7%) patients on warfarin (hazard ratio [HR] 6.9; 95% confidence interval [CI] 1.4-34.5, P = .018). The two patients on DOACs (one taking dabigatran and one taking rivaroxaban) suffered from thromboembolic events, whereas of the six patients with composite outcomes on warfarin, three had thromboembolic events (HR for thrombosis 13.3; 95% CI 2.2-79.9, P = .005).

CONCLUSION

These data further support the use of warfarin in high-risk patients with antiphospholipid syndrome.

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.

Direct oral anticoagulants: evidence and unresolved issues

Currently licenced direct oral anticoagulants selectively target thrombin (eg, dabigatran) or coagulation factor Xa (eg, apixaban, betrixaban, edoxaban, and rivaroxaban). Designed to be given in fixed doses without routine monitoring, direct oral anticoagulants have a lower propensity for food and drug interactions than do vitamin K antagonists, and in randomised controlled trials involving around 250 000 patients, they were at least as effective for prevention and treatment of thrombosis and were associated with a lower risk of life-threatening bleeding. The absolute benefits of direct oral anticoagulants over vitamin K antagonists are modest; however, guidelines recommend them in preference to vitamin K antagonists for most indications because of their ease of use and superior safety. The greatest benefits of direct oral anticoagulants are likely to be in patients who were previously deemed unsuitable for vitamin K antagonist therapy. The emergence of generic preparations is expected to further increase the uptake of direct oral anticoagulants, particularly in countries where they are currently not widely used because of cost. Direct oral anticoagulants are contraindicated in patients with mechanical heart valves and should be used with caution or avoided in patients with advanced kidney or liver disease. In this Therapeutics paper, we review the pharmacology of direct oral anticoagulants, summarise the evidence that led to their approval and incorporation into treatment guidelines, and explore key unresolved issues. We also briefly discuss future perspectives for the development of oral anticoagulants.

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.

The Association between Oral Anticoagulants and Cancer Incidence among Individuals with Nonvalvular Atrial Fibrillation

Objective Existing evidence on the association between vitamin K antagonists (VKAs) and direct oral anticoagulants (DOACs) and cancer is limited and contradictory. No observational studies have been conducted to simultaneously address the cancer safety of VKAs and DOACs. The objective of this study was to determine whether use of VKAs and DOACs, separately, when compared with nonuse, is associated with cancer overall and prespecified site-specific incidence.

Methods Using the United Kingdom Clinical Practice Research Datalink, we identified patients newly diagnosed with nonvalvular atrial fibrillation (NVAF) between 2011 and 2017. Using a time-varying exposure definition, each person-day of follow-up was classified as use of (1) VKAs, (2) DOACs, (3) VKAs and DOACs (drug switchers), and (4) nonuse of anticoagulants (reference). We also conducted a head-to-head comparison of new users of DOACs versus VKAs using propensity score fine stratification weighting. Hazard ratios (HRs) with 95% confidence intervals (CIs) for cancer overall and prespecified subtypes were estimated using Cox proportional hazards models.

Results Compared with nonuse, use of VKAs was not associated with cancer overall (HR: 1.05, 95% CI: 0.91–1.22) or cancer subtypes. Similarly, use of DOACs was not associated with cancer overall (HR: 1.13, 95% CI: 0.93–1.37), but an association was observed for colorectal cancer (HR: 1.73, 95% CI: 1.01–2.99), and pancreatic cancer generated an elevated, though nonsignificant HR (HR: 2.15, 95% CI: 0.72–6.44). Results were consistent in the head-to-head comparison.

Conclusion Use of oral anticoagulants is not associated with the incidence of cancer overall among patients with NVAF. Possible associations between DOACs and colorectal and pancreatic cancer warrant further study.

Novel antithrombotic strategies for treatment of venous thromboembolism

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), is the third most common cause of vascular death after heart attack and stroke. Anticoagulation therapy is the cornerstone of VTE treatment. Despite such therapy, up to 50% of patients with DVT develop postthrombotic syndrome, and up to 4% of patients with PE develop chronic thromboembolic pulmonary hypertension. Therefore, better therapies are needed. Although direct oral anticoagulants are more convenient and safer than warfarin for VTE treatment, bleeding remains the major side effect, particularly in cancer patients. Factor XII and factor XI have emerged as targets for new anticoagulants that may be safer. To reduce the complications of VTE, attenuation of thrombin activatable fibrinolysis inhibitor activity is under investigation in PE patients to enhance endogenous fibrinolysis, whereas blockade of leukocyte interaction with the vessel wall is being studied to reduce the inflammation that contributes to postthrombotic syndrome in DVT patients. Focusing on these novel antithrombotic strategies, this article explains why safer anticoagulants are needed, provides the rationale for factor XII and XI as targets for such agents, reviews the data on the factor XII- and factor XI-directed anticoagulants under development, describes novel therapies to enhance fibrinolysis and decrease inflammation in PE and DVT patients, respectively, and offers insights into the opportunities for these novel VTE therapies.

Perioperative management of patients receiving non-vitamin K antagonist oral anticoagulants: up-to-date recommendations

Indications of non-vitamin K antagonist oral anticoagulants (NOACs), consisting of two types: direct thrombin inhibitor (dabigatran) and direct factor Xa inhibitor (rivaroxaban, apixaban, and edoxaban), have expanded over the last few years. Accordingly, increasing number of patients presenting for surgery are being exposed to NOACs, despite the fact that NOACs are inevitably related to increased perioperative bleeding risk. This review article contains recent clinical evidence-based up-to-date recommendations to help set up a multidisciplinary management strategy to provide a safe perioperative milieu for patients receiving NOACs. In brief, despite the paucity of related clinical evidence, several key recommendations can be drawn based on the emerging clinical evidence, expert consensus, and predictable pharmacological properties of NOACs. In elective surgeries, it seems safe to perform high-bleeding risk surgeries 2 days after cessation of NOAC, regardless of the type of NOAC. Neuraxial anesthesia should be performed 3 days after cessation of NOACs. In both instances, dabigatran needs to be discontinued for an additional 1 or 2 days, depending on the decrease in renal function. NOACs do not require a preoperative heparin bridge therapy. Emergent or urgent surgeries should preferably be delayed for at least 12 h from the last NOAC intake (better if > 24 h). If surgery cannot be delayed, consider using specific reversal agents, which are idarucizumab for dabigatran and andexanet alfa for rivaroxaban, apixaban, and edoxaban. If these specific reversal agents are not available, consider using prothrombin complex concentrates.

Activated αIIbβ3 on platelets mediates flow-dependent NETosis via SLC44A2

Platelet-neutrophil interactions are important for innate immunity, but also contribute to the pathogenesis of deep vein thrombosis, myocardial infarction and stroke. Here we report that, under flow, von Willebrand factor/glycoprotein Ibα-dependent platelet 'priming' induces integrin αIIbβ3 activation that, in turn, mediates neutrophil and T-cell binding. Binding of platelet αIIbβ3 to SLC44A2 on neutrophils leads to mechanosensitive-dependent production of highly prothrombotic neutrophil extracellular traps. A polymorphism in SLC44A2 (rs2288904-A) present in 22% of the population causes an R154Q substitution in an extracellular loop of SLC44A2 that is protective against venous thrombosis results in severely impaired binding to both activated αIIbβ3 and VWF-primed platelets. This was confirmed using neutrophils homozygous for the SLC44A2 R154Q polymorphism. Taken together, these data reveal a previously unreported mode of platelet-neutrophil crosstalk, mechanosensitive NET production, and provide mechanistic insight into the protective effect of the SLC44A2 rs2288904-A polymorphism in venous thrombosis.

Anticoagulation management strategies in heart transplantation

Anticoagulation before, during, and after heart transplantation (HT) presents unique challenges to clinicians. Bleeding and thrombotic morbidity continues to affect this patient population throughout all phases of the HT journey. Reversal is commonly required since patients are commonly bridged to HT with left ventricular assist devices, which require chronic anti platelet and anticoagulation. Caution must be exercised in patients requiring cardiopulmonary bypass during surgery who are at risk of complications from heparin induced thrombocytopenia. The reported incidence of venous thromboembolism following HT is high, particularly during the first post-HT year, most likely due to surgery, biopsies, specific immunosuppression (mTOR inhibitors) and immobilization. It is crucial to maintain long-term oral anticoagulation after the first venous thromboembolism event, especially when risk factors exist. A major issue, and one for which there remains considerable debate, is the optimal treatment of such complications, particularly upper extremity venous thrombosis. For both warfarin and the thrombin inhibitors or Factor Xa inhibitors, the clinician must determine potential drug interactions based on the HT drug regimen, and then develop a patient-specific management strategy.

Fifty years of research on antithrombotic therapy: Achievements and disappointments

The achievements with antithrombotic therapy over the past 50 years have been monumental and the disappointments relatively few. In this review, we will discuss, chronologically, the major developments of the two recognized classes of antithrombotics - anticoagulants and antiplatelet agents.

Factors associated with women's adherence to postpartum thromboprophylaxis

Postpartum low-molecular-weight heparin (LMWH) thromboprophylaxis is indicated for a substantial proportion of women. We assessed women's adherence to postpartum thromboprophylaxis and the factors associated with adherence. This retrospective cohort study was conducted at a university hospital during 2018. Parturients for whom a recommendation for LMWH prophylaxis was given at discharge from the maternity ward were contacted at the end of the recommended post-discharge course of LMWH, and were invited to participate in a telephone survey. The main outcome measures were optimal (> 80%) and suboptimal adherence (< 80%) to LMWH administration, reasons for nonadherence, and views regarding LMWH, as assessed by an adapted Beliefs about Medication Questionnaire. Overall, 250 women completed the questionnaire. The median recommended duration of post-discharge LMWH was 7 [5-8] days. Suboptimal adherence was reported by 82 (32.8%); 45 (18.0%) women did not administer any LMWH dose following discharge and only 147 (58.8%) completed the full LMWH course. In multivariate analysis, patients' perceptions of the necessity of LMWH [odds ratio (95% CI): 3.50 (2.12, 9.53), P = 0.002] and of the adequacy of the explanation given prior to discharge regarding LMWH technical administration [odds ratio (95% CI): 5.0 (2.33, 11.11), P < 0.001] were positively associated with optimal adherence. Nearly one-third of women prescribed postpartum LMWH thromboprophylaxis reported suboptimal adherence. Patients' perceptions of the necessity of the treatment and their opinion of the adequacy of explanation regarding LMWH technical administration were identified as predictors of treatment compliance, and thus represent potential areas for improvement.

Comparison of rivaroxaban and dalteparin for the long-term treatment of venous thromboembolism in patients with gynecologic cancers

Objectives

Two randomized, controlled studies comparing outcomes in patients treated with direct oral anticoagulants or low-molecular weight heparin for cancer-associated venous thromboembolism (VTE) have previously been performed. However, gynecologic cancers accounted for approximately 10% of the study populations. We compared the outcomes of patients with primary gynecological cancers who were treated for cancer-associated VTE with either rivaroxaban or dalteparin.

Methods

The 162 eligible patients with gynecologic cancers who were treated with either dalteparin (n=60) or rivaroxaban (n=102) were reviewed. The primary outcome was a composite event, which included recurrence or clinically relevant bleeding events during the therapeutic period. Secondary outcomes were recurrence, clinically relevant bleeding events, and mortality.

Results

During the therapeutic period, there were no significant differences between the groups in the proportion of composite events, recurrence, or clinically relevant bleeding. Multivariate analysis using the Cox proportional hazards model also showed no significant difference in the number of composite events and clinically relevant bleeding between the groups. In the rivaroxaban group, 44.0% of patients experienced gastrointestinal bleeding and 24.0% experienced urinary tract bleeding. In the dalteparin group, bleeding was most common in the urinary tract (44.4%) and at the injection site (22.2%).

Conclusion

In this study, although there were no significant differences in effectiveness or safety between the rivaroxaban and dalteparin groups, rivaroxaban use was associated with a higher rate of clinically relevant bleeding than dalteparin. Therefore, caution should be taken when prescribing rivaroxaban for gynecologic cancer-associated VTE and bleeding events should be carefully monitored.

Treatment of Cancer-Associated Thrombosis: Beyond HOKUSAI

Direct oral anticoagulants (DOACs) represent an attractive alternative to low-molecular-weight heparins (LMWHs) for the long-term treatment of cancer-associated thrombosis (CT) since they avoid the burden of daily injections. Analyses in subgroups of cancer patients from large randomized trials suggested that DOACs were at least as effective as vitamin K antagonists, while indirect comparisons suggested that DOACs' efficacy and safety profile were comparable to those of LMWHs. In the randomized controlled HOKUSAI-VTE Cancer study, currently the only completed phase III trial on DOACs in CT patients, edoxaban was shown noninferior to dalteparin on the composite primary endpoint of time to first recurrent venous thromboembolism or major bleeding during the 12 months after randomization. Study results suggest that both agents had comparable benefit/risk ratio in patients with CT. Even though this conclusion was valid from a strict statistical viewpoint, it was potentially misleading when interpreting benefit/risk ratios. Besides the obvious heterogeneity of the study population (e.g., 23% of patients no longer had cancer) and significantly different treatment durations between arms, secondary outcomes for efficacy were in favor of edoxaban for recurrent deep-vein thrombosis but not for recurrent pulmonary embolism, and major bleeding episodes were significantly more frequent in the edoxaban group, with an excess of gastrointestinal (GI) bleeding episodes observed mainly but not only in patients with GI cancers. More research is needed regarding specific patients' profiles, cancer types, and treatment period to better clarify the respective roles of DOACs and LMWHs in CT patients.