Bleeding risk and the management of bleeding complications in patients undergoing anticoagulant therapy: focus on new anticoagulant agents

Preparation and structural characterization of a sulfated octasaccharide with heparin-like anticoagulant activity

Heparins are sulfated polysaccharides with a heterogeneous mixture derived from animal tissues, subject to supply limitations and the risk of animal virus residues. Patients using heparin also face the risks of spontaneous bleeding and thrombocytopenia. Here we reported an efficient riclinoctaose-based approach for rapid chemical synthesis of a structurally defined heparin-like anticoagulant sulfated octasaccharide (SRO). We used sulfur trioxide-pyridine, sulfur trioxide-trimethylamine, and sulfur trioxide-triethylamine complexes as solvents for one-pot O-sulfation and determined the optimal conditions for synthesizing SRO. Sulfur trioxide-trimethylamine provided reasonable control over the degree of substitution between 1.85 and 1.88, revealing a single molecule with a theoretical molecular weight of 2952.96 g/mol. The structural features of the SRO were carried out by Fourier transform infrared spectroscopy and one- and two- dimensional 1H and 13C NMR analysis, revealing sulfation repeatedly present at the fixed positions of C-6/C-2/C-3 and reducing terminals. The anticoagulant activity of SRO was demonstrated by efficiently blocking coagulation in the blood of mice and human. SRO dose-dependently decreased ferric chloride-induced experimental thrombosis in mice. Like heparin, SRO specifically inhibits coagulation factor Xa, but significantly reduces the risk of bleeding compared to heparin. Therefore, we named it octaparin. These results support that octaparin is expected to replace animal-sourced heparin.

Synthesis, Biological Evaluation and Reversal of Sulfonated Di- and Triblock Copolymers as Novel Parenteral Anticoagulants

Despite targeting different coagulation cascade sites, all Food and Drug Administration-approved anticoagulants present an elevated risk of bleeding, including potentially life-threatening intracranial hemorrhage. Existing studies have not thoroughly investigated the efficacy and safety of sulfonate polymers in animal models and fully elucidate the precise mechanisms by which these polymers act. The activity and safety of sulfonated di- and triblock copolymers containing poly(sodium styrenesulfonate) (PSSS), poly(sodium 2-acrylamido-2-methylpropanesulfonate) (PAMPS), poly(ethylene glycol) (PEG), poly(sodium methacrylate) (PMAAS), poly(acrylic acid) (PAA), and poly(sodium 11-acrylamidoundecanoate) (PAaU) blocks are synthesized and assessed. PSSS-based copolymers exhibit greater anticoagulant activity than PAMPS-based ones. Their activity is mainly affected by the total concentration of sulfonate groups and molecular weight. PEG-containing copolymers demonstrate a better safety profile than PAA-containing ones. The selected copolymer PEG47-PSSS32 exhibits potent anticoagulant activity in rodents after subcutaneous and intravenous administration. Heparin Binding Copolymer (HBC) completely reverses the anticoagulant activity of polymer in rat and human plasma. No interaction with platelets is observed. Selected copolymer targets mainly factor XII and fibrinogen, and to a lesser extent factors X, IX, VIII, and II, suggesting potential application in blood-contacting biomaterials for anticoagulation purposes. Further studies are needed to explore its therapeutic applications fully.

The efficacy and safety of direct oral anticoagulants in the treatment of the acute phase of heparin-induced thrombocytopenia: A systematic review

PURPOSE

To investigate the safety and efficacy of direct oral anticoagulants (DOACs) in the treatment of the acute phase of heparin-induced thrombocytopenia (HIT).

SUMMARY

A systematic review of the literature was conducted on PubMed, MEDLINE, Embase, and Web of Science Core Collection through July 2023. Search terms included "heparin-induced thrombocytopenia AND direct-oral-anticoagulants" in addition to a list of oral anticoagulants. Adult patients who used direct oral anticoagulants as the initial treatment for the acute phase of HIT were included. A total of 1,188 articles were initially identified, with 770 articles reviewed following removal of duplicates. Following the application of inclusion and exclusion criteria, 12 articles were ultimately included. Rivaroxaban was the most-utilized DOAC (28 patients), followed by apixaban (7 patients) and dabigatran (1 patient). All patients with thrombocytopenia demonstrated successful platelet recovery, with two patients presenting with normal platelet counts. One patient developed a deep venous thrombosis with no other new or recurrent thromboses. There were no reported clinically significant adverse events in any patient. Obstacles and deterrents to the use of the standards of care in the acute phase of HIT exist. Argatroban and bivalirudin require intravenous infusion and require close aPTT monitoring and dose adjustment. Fondaparinux requires injection and is contraindicated with body weight <50kg. DOACs would offer the novel ability for an oral treatment in the treatment of the acute phase HIT and allow for minimal monitoring and consistent dosing strategies. Therefore, DOACs are an intriguing choice for the treatment of the acute phase of HIT.

CONCLUSION

Data from 12 publications and across 36 patients suggests that the use of DOACs in the acute phase of HIT may be a safe and efficacious treatment option with favorable ease of monitoring and management.

Suppressing upregulation of fibrinogen after polytrauma mitigates thrombosis in mice

BACKGROUND

Polytrauma results in systemic inflammation and increased circulating fibrinogen, which increases the risk of microvascular and macrovascular thrombosis that contributes to secondary organ damage and venous thromboembolism (VTE). There are no clinically approved agents to prevent hyperfibrinogenemia after polytrauma. We hypothesized that preventing the increase in fibrinogen levels after polytrauma would suppress thrombosis.

METHODS

Small-interfering ribonucleic acid (siRNA) against fibrinogen was encapsulated in lipid nanoparticles (siFibrinogen). Mice underwent a model of polytrauma and were then given varying doses of siFibrinogen, control siRNA, or no treatment. Fibrinogen was measured for 1 week via enxyme-linked immunosorbent assay (ELISA). To model postinjury VTE, the inferior vena cava was ligated 2 days after polytrauma in a portion of the mice. Thrombus weight was measured 48 hours after the inferior vena cava was ligated.

RESULTS

Treatment with siFibrinogen prevented hyperfibrinogenemia after trauma without exacerbating the hypofibrinogenemic state that occurs in the acute injury period (1 hour). In treated groups, fibrinogen was significantly lower from 6 hours postinjury through the 7-day monitoring period. Maximal fibrinogen reduction was observed at 72 hours. Here, mice that received 2.0 mg/kg of siFibrinogen had 1% of normal values relative to untreated mice, and mice that received 1.0 or 0.5 mg/kg had 4%. Mice treated with siFibrinogen that underwent the postinjury VTE model had significantly reduced thrombus weight compared with control siRNA-treated animals. More notably, among all siFibrinogen treated mice, 12 of 18 were completely protected from thrombosis, compared with 0 of 9 displaying protection in the control group.

CONCLUSION

The rise of fibrinogen and the size of thrombi after polytrauma can be mitigated via the administration of siRNA against fibrinogen. siFibrinogen represents a promising novel target for VTE prophylaxis posttrauma.

Electronic consultation to improve care outcomes in patients with suspected and confirmed heparin-induced thrombocytopenia

Background

Heparin-induced thrombocytopenia (HIT) is a complication of heparin exposure associated with high risk for morbidity and mortality. Diagnosis and management are complex due to limitations of laboratory testing and the need for nonheparin anticoagulation.

Objectives

To increase the delivery of evidence-based care of patients with suspected and confirmed HIT via electronic consultation (e-consult).

Methods

We describe the creation and implementation of an e-consult service for patients with concern for HIT at a large academic medical center. Hematology physicians with HIT expertise performed real-time chart review of all patients with a positive screening immunoassay result and provided written recommendations in their electronic health record.

Results

Comparison of outcomes for 1 year before and the year after the e-consult service implementation identified improvements in direct thrombin inhibitor stewardship, increased diagnostic accuracy, and decreased length of stay of patients with confirmed HIT.

Conclusion

The e-consult platform is a novel method for rapid, targeted consultative guidance, and this single-institution pilot demonstrates its feasibility and effectiveness to improve the care of patients with suspected and confirmed HIT.

Thrombotic and Hemorrhagic Outcomes After Elective Surgery in Preoperatively Anticoagulated Patients

OBJECTIVE

To better understand the incidence and timing of thrombotic and hemorrhagic complications in anticoagulated patients undergoing elective surgery.

METHODS

Using institutional American College of Surgeons National Surgical Quality Improvement Program data, we identified patients receiving preoperative anticoagulation undergoing elective surgery between 2011 and 2021. Medical records review supplemented National Surgical Quality Improvement Program data to detail complication and anticoagulation type and timing. Outcomes for postoperative hemorrhage, acute venous thromboembolism (VTE), and cerebrovascular accident (CVA) were collected.

RESULTS

A total of 1442 patients met inclusion criteria, and 84 patients (5.8%) experienced 1 or more complications. There were 4 CVA (0.3%), 16 VTE (1.1%), and 68 bleeding (4.7%) events postoperatively. Three patients (75%) with CVA, 10 patients (62.5%) with VTE, and 18 patients (26.5%) with postoperative bleeding had resumed therapeutic anticoagulation before the complication. In terms of long-term sequelae in the CVA cohort, there was 1 mortality (25%), and an additional patient (25%) continues to experience long-term physical and mild cognitive impairments. Patients who experienced postoperative VTE required only anticoagulation adjustments. In patients who experienced bleeding complications, 6 (8.8%) required intensive care unit admissions, and there was 1 mortality (1.5%).

CONCLUSION

Despite the increased use of anticoagulation over time, balancing postoperative bleeding and thrombotic risks remains challenging. Bleeding complications were most common in preoperatively anticoagulated patients undergoing elective surgery. Earlier postoperative resumption of anticoagulation is unlikely to prevent thrombotic events as 65% of patients had already resumed therapeutic anticoagulation.

Pleiotropic Effects of Direct Oral Anticoagulants in Chronic Heart Failure and Atrial Fibrillation: Machine Learning Analysis

Oral anticoagulant therapy (OAT) for managing atrial fibrillation (AF) encompasses vitamin K antagonists (VKAs, such as warfarin), which was the mainstay of anticoagulation therapy before 2010, and direct-acting oral anticoagulants (DOACs, namely dabigatran etexilate, rivaroxaban, apixaban, edoxaban), approved for the prevention of AF stroke over the last thirteen years. Due to the lower risk of major bleeding associated with DOACs, anticoagulant switching is a common practice in AF patients. Nevertheless, there are issues related to OAT switching that still need to be fully understood, especially for patients in whom AF and heart failure (HF) coexist. Herein, the effective impact of the therapeutic switching from warfarin to DOACs in HF patients with AF, in terms of cardiac remodeling, clinical status, endothelial function and inflammatory biomarkers, was assessed by a machine learning (ML) analysis of a clinical database, which ultimately shed light on the real positive and pleiotropic effects mediated by DOACs in addition to their anticoagulant activity.

The association of timing of coronary artery bypass grafting for non-ST-elevation myocardial infarction and clinical outcomes in the contemporary United States

BACKGROUND

In contrast to the timing of coronary angiography and percutaneous coronary intervention, the optimal timing of coronary artery bypass grafting (CABG) in non-ST-elevation myocardial infarction (NSTEMI) has not been determined. Therefore, we compared in-hospital outcomes according to different time intervals to CABG surgery in a contemporary NSTEMI population in the USA.

METHODS

We identified all NSTEMI hospitalizations from 2016 to 2020 where revascularization was performed with CABG. We excluded NSTEMI with high-risk features using prespecified criteria. CABG was stratified into ≤24 h, 24-72 h, 72-120 h, and >120 h from admission. Outcomes of interest included in-hospital mortality, perioperative complications, length of stay (LOS), and hospital cost.

RESULTS

A total of 147 170 NSTEMI hospitalizations where CABG was performed were assessed. A greater percentage of females, Blacks, and Hispanics experienced delays to CABG surgery. No difference in in-hospital mortality was observed, but CABG at 72-120 h and at >120 h was associated with higher odds of non-home discharge and acute kidney injury compared with CABG at ≤24 h from admission. In addition to these differences, CABG at >120 h was associated with higher odds of gastrointestinal hemorrhage and need for blood transfusion. All 3 groups with CABG delayed >24 h had longer LOS and hospital-associated costs compared with hospitalizations where CABG was performed at ≤24 h.

CONCLUSION

CABG delays in patients with NSTEMI are more frequently experienced by women and minority populations and are associated with an increased burden of complications and healthcare cost.

Antidote-controlled DNA aptamer modulates human factor IXa activity

Thrombosis leads to elevated mortality rates and substantial medical expenses worldwide. Human factor IXa (HFIXa) protease is pivotal in tissue factor (TF)-mediated thrombin generation, and represents a promising target for anticoagulant therapy. We herein isolated novel DNA aptamers that specifically bind to HFIXa through systematic evolution of ligands by exponential enrichment (SELEX) method. We identified two distinct aptamers, seq 5 and seq 11, which demonstrated high binding affinity to HFIXa (Kd = 74.07 ± 2.53 nM, and 4.93 ± 0.15 nM, respectively). Computer software was used for conformational simulation and kinetic analysis of DNA aptamers and HFIXa binding. These aptamers dose-dependently prolonged activated partial thromboplastin time (aPTT) in plasma. We further rationally optimized the aptamers by truncation and site-directed mutation, and generated the truncated forms (Seq 5-1t, Seq 11-1t) and truncated-mutated forms (Seq 5-2tm, Seq 11-2tm). They also showed good anticoagulant effects. The rationally and structurally designed antidotes (seq 5-2b and seq 11-2b) were competitively bound to the DNA aptamers and effectively reversed the anticoagulant effect. This strategy provides DNA aptamer drug-antidote pair with effective anticoagulation and rapid reversal, developing advanced therapies by safe, regulatable aptamer drug-antidote pair.

An architecturally rational hemostat for rapid stopping of massive bleeding on anticoagulation therapy

Hemostatic devices are critical for managing emergent severe bleeding. With the increased use of anticoagulant therapy, there is a need for next-generation hemostats. We rationalized that a hemostat with an architecture designed to increase contact with blood, and engineered from a material that activates a distinct and undrugged coagulation pathway can address the emerging need. Inspired by lung alveolar architecture, here, we describe the engineering of a next-generation single-phase chitosan hemostat with a tortuous spherical microporous design that enables rapid blood absorption and concentrated platelets and fibrin microthrombi in localized regions, a phenomenon less observed with other classical hemostats without structural optimization. The interaction between blood components and the porous hemostat was further amplified based on the charged surface of chitosan. Contrary to the dogma that chitosan does not directly affect physiological clotting mechanism, the hemostat induced coagulation via a direct activation of platelet Toll-like receptor 2. Our engineered porous hemostat effectively stopped the bleeding from murine liver wounds, swine liver and carotid artery injuries, and the human radial artery puncture site within a few minutes with significantly reduced blood loss, even under the anticoagulant treatment. The integration of engineering design principles with an understanding of the molecular mechanisms can lead to hemostats with improved functions to address emerging medical needs.

Pathophysiology and targeted treatment of cholesterol crystal embolism and the related thrombotic angiopathy

Cholesterol crystal (CC) embolism is a complication of advanced atherosclerotic plaques located in the major arteries. This pathological condition is primarily induced by interventional and surgical procedures or occurs spontaneously. CC can induce a wide range of tissue injuries including CC embolism syndrome, a spontaneous or intervention-induced complication of advanced atherosclerosis, while treatment of CC embolism has remained empiric. Vascular occlusions caused by CC embolism may exceed the ischemia tolerance of many tissues, particularly when small arteries are affected. The main approach to CC embolism is primary prophylaxis in patients at risk by stabilizing atherosclerotic plaques and avoiding unnecessary catheter interventions. During CC embolism, the use of platelet inhibitors to avoid abnormal activation and aggregation and anticoagulants may reduce the risk of vascular occlusions and tissue ischemia. This probably explains the relatively low prevalence of clinical manifestations of CC embolism, which are frequently found in autopsy studies. In this review, we summarized the current knowledge on the pathophysiology of CC embolism syndrome deriving from clinical observations and experimental mouse models. Furthermore, we described the risk factors of CC embolism in humans as well as the experimental studies based on empiric treatments. We also discuss potential therapeutic interventions based on recent experimental data and emerging drug options evolving from other research domains. Given the substantial unmet medical need to improve the outcomes of CC embolism, the identification of effective treatment strategies is urgently needed.

The Role of Injectables in the Treatment and Prevention of Cancer-Associated Thrombosis

Cancer-associated thrombosis (CAT) is a leading cause of death among patients with cancer. CAT can manifest itself as venous thromboembolism (VTE), in the form of deep vein thrombosis or pulmonary embolism, or arterial thromboembolism. The pathophysiology of CAT is complex and depends on cancer-, patient-, treatment- and biomarkers-related factors. Treatment of VTE in patients with cancer is complex and includes three major classes of anticoagulant agents: heparin and its derivatives, e.g., low molecular weight heparins, direct oral anticoagulants (DOACs), and vitamin K inhibitors. Given the tremendous heterogeneity of clinical situations in patients with cancer and the challenges of CAT, there is no single universal treatment option for patients suffering from or at risk of CAT. Initial studies suggested that patients seemed to prefer an anticoagulant that would not interfere with their cancer treatment, suggesting the primacy of cancer over VTE, and favoring efficacy and safety over convenience of route of administration. Recent studies show that when the efficacy and safety aspects are similar, patients prefer the oral route of administration. Despite this, injectables are a valid option for many patients with cancer.

Polyphosphate as an antithrombotic target and hemostatic agent

Polyphosphate (PolyP) is a polymer comprised of linear phosphate units connected by phosphate anhydride bonds. PolyP exists in a diverse range of eukaryotes and prokaryotes with varied chain lengths ranging from six to thousands of phosphate units. Upon activation, human platelets and neutrophils release short-chain PolyP, along with other components, to initiate the coagulation pathway. Long-chain PolyP derived from cellular or bacterial organelles exhibits higher proinflammatory and procoagulant effects compared to short-chain PolyP. Notably, PolyP has been identified as a low-hemorrhagic antithrombotic target since neutralizing plasma PolyP suppresses the thrombotic process without impairing the hemostatic functions. As an inorganic polymer without uniform steric configuration, PolyP is typically targeted by cationic polymers or recombinant polyphosphatases rather than conventional antibodies, small-molecule compounds, or peptides. Additionally, because of its procoagulant property, PolyP has been incorporated in wound-dressing materials to facilitate blood hemostasis. This review summarizes current studies on PolyP as a low-hemorrhagic antithrombotic target and the development of hemostatic materials based on PolyP.

Venous Thromboembolism Prophylaxis in Major Orthopedic Surgeries and Factor XIa Inhibitors

Venous thromboembolism (VTE), comprising pulmonary embolism (PE) and deep vein thrombosis (DVT), poses a significant risk during and after hospitalization, particularly for surgical patients. Among various patient groups, those undergoing major orthopedic surgeries are considered to have a higher susceptibility to PE and DVT. Major lower-extremity orthopedic procedures carry a higher risk of symptomatic VTE compared to most other surgeries, with an estimated incidence of ~4%. The greatest risk period occurs within the first 7-14 days following surgery. Major bleeding is also more prevalent in these surgeries compared to others, with rates estimated between 2% and 4%. For patients undergoing major lower-extremity orthopedic surgery who have a low bleeding risk, it is recommended to use pharmacological thromboprophylaxis with or without mechanical devices. The choice of the initial agent depends on the specific surgery and patient comorbidities. First-line options include low-molecular-weight heparins (LMWHs), direct oral anticoagulants, and aspirin. Second-line options consist of unfractionated heparin (UFH), fondaparinux, and warfarin. For most patients undergoing knee or hip arthroplasty, the initial agents recommended for the early perioperative period are LMWHs (enoxaparin or dalteparin) or direct oral anticoagulants (rivaroxaban or apixaban). In the case of hip fracture surgery, LMWH is recommended as the preferred agent for the entire duration of prophylaxis. However, emerging factor XI(a) inhibitors, as revealed by a recent meta-analysis, have shown a substantial decrease in the occurrence of VTE and bleeding events among patients undergoing major orthopedic surgery. This discovery poses a challenge to the existing paradigm of anticoagulant therapy in this specific patient population and indicates that factor XI(a) inhibitors hold great promise as a potential strategy to be taken into serious consideration.

Analysis of heparin-induced thrombocytopenia diagnostic and management strategies in individuals with inconclusive antibody optical densities

Heparin-induced thrombocytopenia (HIT) is an uncommon but serious complication of exposure to heparin. Antibody optical densities (ODs) used to diagnose HIT exceeding 2 are highly suggestive of disease, whereas ODs less than 0.5 often 'rule out' HIT. Variation in the clinical care of patients with inconclusive ODs between 0.5 and 2 is likely. This single-centre, retrospective analysis evaluates the diagnosis, management and outcomes of those with antibody ODs between 0.5 and 2. We queried our institution's Healthcare Enterprise Repository for Ontological Narration (HERON) database to identify individuals with antibody ODs between 0.5 and 2. Chart review was completed to calculate 4T scores, corroborate diagnosis codes with documented information in our electronic health record (EHR) and evaluate the diagnosis, management and outcomes of these individuals. These data were evaluated using descriptive and univariate statistics. Among individuals evaluated for HIT between November 2007 and July 2020, we identified 302 individuals with ODs between 0.5 and 2. Serotonin release assays (SRAs) were assessed in 55% (165/302) and were positive in 12% (20/165). In those with available data, 96% with low 4T scores had negative SRAs and 4% had positive SRAs. As 4T scores and antibody ODs proportionally increased, SRA positivity also increased. Clinical management varied widely; however, 4T scoring remains a valuable assessment in this cohort. In those with HIT antibody ODs between 0.5 and 2, true positives were uncommon, and their clinical management varied widely. Fortunately, 4T scoring is a useful prognostic tool that improves the diagnosis and management among those with inconclusive HIT.

Bleeding related hospitalizations and mortality in England 2014-2019

Acute bleeding is common and associated with increased morbidity and mortality. Epidemiological studies evaluating trends in bleeding-related hospitalisations and mortality are important as they have potential to guide resource allocation and service provision, however, despite this literature evaluating the national burden and annual trends are lacking. Our objective was to report the national burden and incidence of bleeding-related hospitalisation and mortality.This was a population-based review of all people in England between 2014 and 2019 either admitted to an acute care ward of a National Health Service (NHS) English hospital, or who died. Admissions and deaths were required to have a primary diagnosis of significant bleeding.There was a total of 3,238,427 hospitalisations with a mean of 539,738 ± 6033 per year and 81,264 deaths with a mean of 13,544 ± 331 per year attributable to bleeding. The mean annual incident rate for bleeding-related hospitalisations was 975 per 100,000 patient years and for mortality was 24.45. Over the study period there was a significant 8.2% reduction in bleeding related deaths (χ² test for trend 91.4, p < 0.001). A direct relationship between increasing age and incidence of bleeding-related hospitalisation and mortality was seen.Bleeding remains a common cause of hospitalisation and death. The reduction in bleeding related mortality requires further investigation. This data may serve to guide future interventions designed to reduce bleeding-related morbidity and mortality.

Advances in symptomatic therapy for left ventricular non-compaction in children

Left ventricular non-compaction is a complex cardiomyopathy and the third largest childhood cardiomyopathy, for which limited knowledge is available. Both pathogenesis and prognosis are still under investigation. Currently, no effective treatment strategy exists to reduce its incidence or severity, and symptomatic treatment is the only clinical treatment strategy. Treatment strategies are constantly explored in clinical practice, and some progress has been made in coping with the corresponding symptoms because the prognosis of children with left ventricular non-compaction is usually poor if there are complications. In this review, we summarized and discussed the coping methods for different left ventricular non-compaction symptoms.

Low molecular weight heparin in COVID-19: benefits and concerns

Since its emergence, the COVID-19 pandemic had a dramatic impact on the public health worldwide and it scarred the medical, economical, and social determinants of health. Even after the significant vaccination advances, the disease of SARS-CoV-2 can manifest in severe presentations with life-threatening thromboembolic and multi-organ complications leading to notable morbidity and mortality. Clinicians and researchers are on continuous pursuit of investigating different approaches in the attempt to prevent the infection and minimize its severity. Although the COVID-19's pathophysiology remains relatively unclear, it is well established now that coagulopathy, systemic thrombotic propensity, and a robust immunoinflammatory response are some of the most important determinants of its morbidity and mortality. Accordingly, research efforts have focused on addressing the inflammatory and hematological cascades using available agents to avoid thromboembolic events. Several studies and investigators have emphasized the importance of Low molecular weight heparin (LMWH), namely, Lovenox, in addressing these sequelae of the COVID-19 disease, either prophylactically or therapeutically. This review explores the benefits and concerns of employing LMWH, a widely used anticoagulant, in COVID-19 disease. It delves into Enoxaparin as a molecule, along with its pharmacology, mechanism of action, and clinical uses. It also reviews the current high-quality clinical evidence that highlight the role of enoxaparin in SARS-CoV-2 infection.

Design and Synthesis of Neutralizable Fondaparinux

Fondaparinux, a clinically approved anticoagulant pentasaccharide for the treatment of thrombotic diseases, displays better efficacy and biosafety than other heparin-based anticoagulant drugs. However, there is no suitable antidote available for fondaparinux to efficiently manage its potential bleeding risks, thereby precluding its widespread use. Herein, we describe a convergent and stereocontrolled approach to efficiently synthesize an aminopentyl-functionalized pentasaccharide, which is further used to prepare fondaparinux-based biotin conjugates and clusters. Biological activity evaluation demonstrates that the anticoagulant activity of the fondaparinux-based biotin conjugate and trimer is, respectively, neutralized by avidin and protamine as effective antidotes. This work suggests that our synthetic biotin conjugate and trimer have potential for the development of neutralizable and safe anticoagulant drugs.

Spontaneous epidural hematoma induced by rivaroxaban: A case report and review of the literature

Background:

Trauma is the most frequent reason for epidural bleeding. However, numerous investigation had discovered that anticoagulants such as rivaroxaban could cause epidural hematoma. Here, we present a case of epidural hematoma in young man who got rivaroxaban as treatment of deep vein thrombosis.

Case Description:

A 27-year-old male with a history of deep vein thrombosis and one month of rivaroxaban medication presented with seizure and loss of consciousness following a severe headache. A CT scan of the head revealed epidural bleeding, and emergency blood clot removal was performed. As a reversal, prothrombin complex was utilized.

Conclusion:

Rivaroxaban has the potential to cause an epidural hemorrhage. Reversal anticoagulant should be administered before doing emergency surgery.

A Historical Perspective on the Reversal of Anticoagulants

There has been a landmark shift in the last several decades in the management and prevention of thromboembolic events. From the discovery of parenteral and oral agents requiring frequent monitoring as early as 1914, to the development of direct oral anticoagulants (DOACs) that do not require monitoring or dose adjustment in the late 20th century, great advances have been achieved. Despite the advent of these newer agents, bleeding continues to be a key complication, affecting 2 to 4% of DOAC-treated patients per year. Bleeding is associated with substantial morbidity and mortality. Although specific reversal agents for DOACs have lagged the release of these agents, idarucizumab and andexanet alfa are now available as antagonists. However, the efficacy of these reversal agents is uncertain, and complications, including thrombosis, have not been adequately explored. As such, guidelines continue to advise the use of nonspecific prohemostatic agents for patients requiring reversal of the anticoagulant effect of these drugs. As the indications for DOACs and the overall prevalence of their use expand, there is an unmet need for further studies to determine the efficacy of specific compared with nonspecific pro-hemostatic reversal agents. In this review, we will discuss the evidence behind specific and nonspecific reversal agents for both parenteral and oral anticoagulants.

Bleeding into the Abdominal and Ilio-Lumbar Muscles-A Rare Complication in the Course of COVID-19: Analysis of Four Cases and a Literature Review

The risk of venous thromboembolic (VTE) complications, mainly in the form of pulmonary embolism (PE) and deep vein thrombosis (DVT), in COVID-19 is well known, necessitating the administration of thrombotic prophylaxis in most patients. With a high risk of VTE complications or their presence, full anticoagulation may be associated with hemorrhagic complications. COVID-19 bleeding is rarely reported. Here, we present four cases of patients with muscle bleeding: two in the iliopsoas muscle, which resulted in death despite the embolization of the bleeding vessel, and two in the oblique and straight abdominal muscles, which were treated conservatively. In the reported cases, the severity of the bleeding coincided with the severity of the course of COVID-19. When observing a sudden drop in hemoglobin (Hb) in a patient with COVID-19, one must always remember the possible complications in the form of muscle bleeding, which can be fatal.

Porous Polymers as Universal Reversal Agents for Heparin Anticoagulants through an Inclusion-Sequestration Mechanism

Heparins are widely used anticoagulants for surgical procedures and extracorporeal therapies. However, all of them have bleeding risks. Protamine sulfate, the only clinically approved antidote for unfractionated heparin (UFH), has adverse effects. Moreover, protamine can only partially neutralize low-molecular-weight heparins (LMWHs) and is not effective for fondaparinux. Here, an inclusion-sequestration strategy for efficient neutralization of heparin anticoagulants by cationic porous supramolecular organic frameworks (SOFs) and porous organic polymers (POPs) is reported. Isothermal titration calorimetric and fluorescence experiments show strong binding affinities of these porous polymers toward heparins, whereas dynamic light scattering and zeta potential analysis confirm that the heparin sequences are adsorbed into the interior of the porous hosts. Activated partial thromboplastin time, anti-FXa, and thromboelastography assays indicate that their neutralization efficacies are higher than or as high as that of protamine for UFH and generally superior to protamine for LMWHs and fondaparinux, which is further confirmed by tail-transection model in mice and ex vivo aPTT or anti-FXa analysis in rats. Acute toxicity evaluations reveal that one of the SOFs displays outstanding biocompatibility. This work suggests that porous polymers can supply safe and rapid reversal of clinically used heparins, as protamine surrogates, providing an improved approach for their neutralization.

P- and E- selectin in venous thrombosis and non-venous pathologies

Venous thromboembolism is a very common and costly health problem worldwide. Anticoagulant treatment for VTE is imperfect: all have the potential for significant bleeding, and none prevent the development of post thrombotic syndrome after deep vein thrombosis or chronic thromboembolic pulmonary hypertension after pulmonary embolism. For these reasons, alternate forms of therapy with improved efficacy and decreased bleeding are needed. Selectins are a family (P-selectin, E-selectin, L-selectin) of glycoproteins that facilitate and augment thrombosis, modulating neutrophil, monocyte, and platelet activity. P- and E-selectin have been investigated as potential biomarkers for thrombosis. Inhibition of P-selectin and E-selectin decrease thrombosis and vein wall fibrosis, with no increase in bleeding. Selectin inhibition is a promising avenue of future study as either a stand-alone treatment for VTE or as an adjunct to standard anticoagulation therapies.

Potential Role of the Moderna COVID-19 Vaccine in Enoxaparin’s Effects on Liver Functions

Enoxaparin is commonly used for prophylaxis as an anticoagulant in hospital settings. Although enoxaparin has been known to cause many minor adverse reactions, hepatocellular injury is one of the rare side effects which can impact clinical course, marked by an asymptomatic rise in liver function panel tests. In this paper, we not only delineate the relationship between enoxaparin-induced hepatocellular injury but also associate it with fevers that have not been previously documented. Furthermore, we posit the Moderna COVID19 vaccine as a potential contributor to this outcome. We hypothesize that the link between enoxaparin and hepatic injury is possibly due to the inflammatory state, which may be augmented by the vaccine.

Compressive femoral neuropathy caused by anticoagulant therapy induced retroperitoneal hematoma: A case report

RATIONALE

Spontaneous retroperitoneal hematomas due to anticoagulant therapy rarely occur. Retroperitoneal hematomas can cause severe pain in the groin, quadriceps femoris muscle weakness, hemodynamic instability, and abdominal distension. They rarely cause compressive neuropathy of the femoral nerve transversing the iliacus muscle. Differential diagnosis is not easy because they have similar clinical features to retroperitoneal hematomas.

PATIENT CONCERNS

A 72-year-old female patient whose right arm was stuck in a bookshelf for 5 days developed right cephalic vein thrombosis. After 5 days of intravenous heparin therapy for venous thrombosis, she presented with sudden right groin pain, right leg paresis, hemodynamic instability, and abdominal distension.

DIAGNOSIS

Emergency abdominal and pelvic CT showed a large number of hematomas in the bilateral retroperitoneal space with active bleeding of the right lumbar artery. An electrodiagnostic study was performed 2 weeks later to check for neuromuscular damage in the right lower extremity, and right compressive femoral neuropathy was confirmed.

INTERVENTIONS

Heparin therapy was discontinued; emergency embolization of the lumbar artery was performed. After 2 weeks, the patient started receiving physical, occupational, and transcutaneous electrical stimulation therapies.

OUTCOMES

She became hemodynamically stable after arterial embolization; a significant decrease in hematoma and patency of the femoral nerve was confirmed on follow-up pelvic MRI. After 2 months of comprehensive rehabilitation, the muscle strength of the right leg significantly improved, and the pain disappeared.

LESSONS

Although rare, spontaneous retroperitoneal hematomas may occur in patients receiving anticoagulant medications. They may even occur in patients receiving emergency anticoagulant therapy. Compressive femoral neuropathy due to retroperitoneal hematomas should be considered if muscle weakness and groin pain are observed. Early diagnosis and appropriate treatment plan of compressive femoral neuropathy due to retroperitoneal hematoma are helpful for a good prognosis.

Impact of Correcting Nutritional Deficiency Anemias in the Elderly on Hospitalizations, Falls, and Mortalities

Background

The incidence and prevalence of anemia increase with age, particularly in adults older than 65 years, and it is associated with a number of adverse health outcomes (AHO), particularly hospitalizations, falls and mortalities. Given that approximately one-third of these anemias are due to reversible causes, we studied whether the treatment of nutritional deficiency anemia (NDA), namely iron deficiency anemia (IDA), cobalamin deficiency anemia (CDA), and folate deficiency anemia (FDA), improves AHO; and explored whether each NDA had different AHO.

Methods

We reviewed electronic medical records of our internal medicine office patients aged 65 years or older, who had a diagnosis of anemia in a non-acute setting.

Results

Total 600 patients were included. Mean age was 75.2 years. Thirty-one point three percent had NDA (CDA 15.3%, IDA 12.3%, FDA 3.7%); and 68.7% had other anemias whom we categorized as non-nutritional deficiency anemias (NNDA), which included anemia of chronic disease (11.2%), myelodysplastic syndrome (6.2%), renal insufficiency anemia (5.7%) and unexplained anemia (45.6%). Even after adequate treatment, IDA group had significantly more hospitalizations (median, 25th - 75th: 2 (0 - 4) vs. 0 (0 - 1), P < 0.001), falls (median, 25th - 75th: 1 (0 - 3) vs. 0 (0 - 1), P < 0.001) and mortalities (10.8% vs. 3.4%, P = 0.011); CDA group had significantly more hospitalizations (median, 25th - 75th: 1 (0 - 2) vs. 0 (0 - 1), P = 0.007), but no difference in falls (median, 25th - 75th: 0 (0 - 1) vs. 0 (0 - 1), P = 0.171) and mortalities (7.6% vs. 3.4%, P = 0.083); and FDA group had significantly more hospitalizations (median, 25th - 75th: 1 (0 - 2) vs. 0 (0 - 1), P = 0.001), but no difference in falls (median, 25th - 75th: 0 (0 - 1) vs. 0 (0 - 1), P = 0.615) and mortalities (4.5% vs. 3.4%, P = 0.550), compared to the NNDA group. Age, Black race, higher number of comorbidities, presence of malignancy and use of direct oral anticoagulants were associated with increased odds of AHO in patients with NDA.

Conclusions

Compared to the patients with NNDA, patients with IDA had more hospitalizations, falls and mortalities even after adequate treatment; while patients with CDA and FDA had only more hospitalizations. Adequate treatment mitigated falls and mortalities in elderly patients with CDA and FDA.

Occam's Razor and Managing Acute Thrombosis in the COVID-19 Era

The COVID-19 pandemic has profoundly influenced the practice of medicine in Australia over the last 24 months. Recently, the development of several vaccines to COVID-19 has been accompanied by reports of an associated rare syndrome of thrombosis and thrombocytopaenia (VITTS). The possibility of this rare disorder confronts all clinicians who deal with acute thrombosis, particularly given the prevalence of patients who have recently been immunised. However, VITTS remains rare, and we believe unnecessary focus on its potential diagnosis may distract from other more common causes of acute thrombosis. We discuss this with reference to a recent case at our institution.

Bleeding outcomes of inpatients receiving therapeutic plasma exchange: A propensity-matched analysis of the National Inpatient Sample

BACKGROUND

Although therapeutic plasma exchange (TPE) is associated with hemostatic abnormalities, its impact on bleeding outcomes is unknown. Therefore, the main study objective was to determine bleeding outcomes of inpatients treated with TPE.

STUDY DESIGN AND METHODS

In a cross-sectional analysis of the National Inpatient Sample (NIS), discharges were identified with 10 common TPE-treated conditions. A 1:3 propensity-matched analysis of TPE- to non-TPE-treated discharges was performed. The primary outcome was major bleeding and secondary outcomes were packed red blood cell (PRBC) transfusion, mortality, disposition, hospital length of stay (LOS), and charges. Multivariable regression analyses were used to examine the association between TPE and study outcomes.

RESULTS

The study population was 15,964 discharges, of which 3991 were TPE- treated. The prevalence of major bleeding was low (5.4%). When compared to non-TPE discharges, TPE had a significant and positive association with major bleeding (OR = 1.37, 95% CI: 1.16-1.63, p = .0003). TPE was also associated with PRBC transfusion (OR = 1.66, 95% CI: 1.42-1.94, p < .0001), in-hospital mortality (OR = 1.45, 95% CI: 1.10-1.90, p = .0008), hospital length of stay (12.45 [95% CI: 11.95-12.97] vs. 7.38 [95% CI: 7.12-7.65] days, p < .0001) and total charges, ($125,123 [95% CI: $119,220-$131,317] vs. $61,953 [95% CI: $59,391-$64,625], p < .0001), and disposition to non-self-care (OR = 1.29, 95% CI: 1.19-1.39, p < .0001).

DISCUSSION

The use of TPE in the inpatient setting is positively associated with bleeding; however, with low prevalence. Future studies should address risk factors that predispose patients to TPE-associated bleeding.

MDCTA volumetric analysis for the quantification and grading of acute non-cerebral, non-gastrointestinal hemorrhage: a feasibility study

PURPOSE

To assess the feasibility of multi-detector computed tomography angiography (MDCTA) volumetry for the quantification and grading of acute non-cerebral, non-gastrointestinal bleeding.

METHODS

This retrospective, single-center study investigated consecutive patients with MDCTA positive for active non-cerebral, non-gastrointestinal bleeding, between January 2020 and June 2020. Outcome measures were the quantification of active extravasation at the arterial and parenchymal phase using volumetry measurements, the calculation of active bleeding rate and bleeding grading, 30-day mortality rate, identification of independent predictors of mortality and correlation between volumetric analysis, various clinical features, and the decision to proceed with an intervention.

RESULTS

In total 30 patients (17 females; 56.6%; mean age 70.0 ± 16.0 years) were analyzed. Volumetric analysis was feasible in all cases resulting in excellent inter-observer variability (interclass correlation coefficient 0.999 for arterial and 0.919 for venous volume measurements). Mean volume of contrast extravasation was 1.06 ± 1.09 ml and 3.07 ± 2.48 ml at the arterial and parenchymal phases, respectively. Mean bleeding rate was 6.95 ± 7.82 ml/min. High bleeding volume at arterial phase (grade 4 bleeding) was the only independent predictor of 30-day mortality (HR 1383.58; p = 0.042). There was a positive correlation between bleeding volume at arterial phase (r_s = 0.340; p = 0.033) and arterial bleeding rate (r_s = 0.381; p = 0.019) with the decision to proceed with an intervention. Bleeding volume of 0.6 ml was the cutoff value for the prediction of intervention (sensitivity 96.3%; specificity 66.7%).

CONCLUSIONS

MDCTA volumetric analysis for the quantification and grading of acute hemorrhage was feasible with excellent inter-observer agreement. The proposed bleeding grading system could optimize decision making and predict clinical outcomes.

Rheological and clot microstructure evaluation of heparin neutralization by UHRA and protamine

The current study reports the use of small amplitude oscillatory rheometry to investigate the dynamics of blood clot formation upon heparin neutralization under three different oscillatory frequencies, two of which were mimicking physiological heart rates. We utilized two different heparin antidotes, namely protamine and newly developed universal heparin reversal agent (UHRA-7), at different concentrations to determine the quality of blood clot formed upon heparin neutralization by analyzing several key rheological parameters. Scanning electron microscopy (SEM) was used to determine the morphology and microstructure of the blood clot after heparin neutralization to support the rheological observations. The current study revealed that the structure of blood clots formed had significant differences when an oscillatory frequency that mimicked the physiological heart rate was used in comparison to a lower frequency commonly used in current clinical measurements. The limited working dose range for protamine and its intrinsic anticoagulation behaviour was observed. The neutralization profile of UHRA-7 showed a large window of activity. The global assessment of rheological parameters and microstructure of the clot together revealed additional details describing anticoagulant reversal and blood coagulation dynamics by relating the blood clot's fiber thickness and the oscillatory measurements, including storage modulus and blood clot's contractile force. Additionally, a mechanical characterization was conducted to provide a further assessment of blood coagulation using the rheological data.

Transient blood thinning during extracorporeal blood purification via the inactivation of coagulation factors by hydrogel microspheres

During extracorporeal blood purification, anticoagulants are administered to prevent thrombogenesis. However, haemorrhagic complications owing to near-complete inactivation of blood coagulation and delayed recovery of haemostasis pose serious risks to patients. Here, we show in vitro and in beagle dogs that hydrogel microspheres that adsorb the coagulation factors VIII, IX and XI provide transient blood thinning when placed in the extracorporeal circuit before blood purification. The microspheres inhibited the activities of the coagulation factors by levels (~8-30%) similar to those occurring in mild haemophilia. On its reintroduction into the animal, the purified pseudo-haemophilic blood favoured faster recovery of haemostasis. The transient blood-thinning strategy may increase the safety of clinical blood-purification procedures.

Heparin-like anticoagulant polypeptides with tunable activity: Synthesis, characterization, anticoagulative properties and clot solubilities in vitro

Due to the uncontrollable anticoagulant activity and limited source, Heparin, which is commonly used in clinical anticoagulation therapies, faces the risk of spontaneous bleeding and thrombocytopenia. Herein, a series of anionic poly(amino acid) s poly (l-Serine-ran-L-Glutamic acid-ran-L-Cysteine-SO₃) (PSEC-SO₃) were prepared by the controlled Ring Opening Polymerization (ROP) of N-Carboxyanhydrides (NCAs). The anticoagulant activities of PSEC-SO₃ can be regulated by simply adjusting the feeding ratio of monomers. In vitro tests show that these polypeptides can effectively prolong the Activated Partical Thromboplastin Time (APTT) and inhibit Factor IIa and Factor Xa, but has no significant effect on Prothrombin Time (PT) and Thrombin Time (TT), which indicates that PSEC-SO₃ mainly act on the intrinsic pathway. In summary, the activity-tunable heparin-like polypeptides are expected to have good application prospects in the anticoagulant field.

An investigation of sickle cell trait, body mass index, and fitness in relation to venous thromboembolism among African American adults

BACKGROUND

The relationships of sickle cell trait (SCT), body mass index (BMI), and physical fitness to venous thromboembolism (VTE) in young adults have received little attention.

OBJECTIVES

To test for associations among SCT, BMI, fitness, and VTE.

PATIENTS/METHODS

We conducted a retrospective cohort study of 48,316 SCT-tested, African American individuals in the US Army during 2011-14. We used Cox proportional hazards models to compute adjusted hazards of deep vein thrombosis (DVT) and pulmonary embolism (PE) associated with selected factors.

RESULTS

Incidence rates of DVT and PE were 1.09 and 0.91 cases per 1000 person-years, respectively. Adjusted hazard ratios (aHRs) for DVT for men and women with SCT were 0.9 (95% confidence interval [CI]: 0.4-2.0; P = .711) and 1.51 (CI: 0.7-3.2; P = .274), respectively. aHRs for PE for SCT+ men and women were 1.1 (CI: 0.5-2.4; P = .773) and 1.2 (CI: 0.5-3.1; P = .650), respectively. Low physical fitness was associated with DVT and PE in women (DVT aHR =3.1; CI: 1.4-6.5; P = .004; PE aHR =4.6; CI: 2.1-9.9; P < .001) and DVT in men (aHR =2.2; CI: 1.0-4.6; P = .048). Recent weight gain of 1 or more BMI points was associated with DVT in men (aHR =1.8; CI: 1.1-2.8; P = .017).

CONCLUSIONS

We found no evidence of increased VTE risk associated with SCT in this population. However, lower fitness levels and BMI increases were so associated.

[Pathophysiology of bleeding]

Bleeding is associated with an increased morbidity and mortality. Anatomic and hemostatic causes play a central role in the pathophysiology of bleeding, with anatomic causes being by far more common. While trauma and invasive procedures are the leading causes of bleeding in surgical disciplines, gastrointestinal bleeding is the major cause of bleeding in internal medicine. Major bleedings lead to secondary homeostatic changes, which in turn not only contribute to further bleeding, but also to the pathogenesis of organ dysfunction. Acquired coagulopathies due to antithrombotic treatment or an underlying disease also contribute to the extent and the dynamics of bleeding, while hereditary bleeding disorders are seldom. The balance between the physiological pro- and anticoagulant pathway plays a significant role in the pathophysiology of bleeding and coagulation. Therefore, the pathophysiology of bleeding cannot be described by means of easily available laboratory coagulation workup. The aim of coagulation correction during the management of life-threatening bleeding is not to normalize coagulation, but rather to stop bleeding. Besides a careful clinical evaluation of the course of bleeding coupled with basic understanding of the physiology of coagulation, targeted laboratory coagulation workup can contribute to a rational coagulation treatment concept.

Efficacy and Selectivity of FGF2-Saporin Cytosolically Delivered by PCI in Cells Overexpressing FGFR1

Fibroblast growth factor receptors (FGFRs) have become an attractive target in cancer research and therapy due to their implication in several cancers. Limitations of current treatment options require a need for additional, more specific and potent strategies to overcome cancers driven by FGFRs. Photochemical internalization (PCI) is a light-controlled method for cytosolic delivery of drugs that are entrapped in endosomes and lysosomes. We here evaluated the efficacy and selectivity of PCI of FGF2-saporin (FGF-SAP) in cells overexpressing FGFR1. FGF-SAP is a conjugate of FGF2 and the highly cytotoxic ribosome-inactivating protein (RIP) saporin, which is used as payload to eliminate cancer cells. Evaluation of the targeting effect of PCI of FGF-SAP was done by comparing the cytotoxic response in osteosarcoma cells with very low levels of FGFR1 (U2OS) to cells overexpressing FGFR1 (U2OS-R1). We demonstrate that PCI greatly enhances cytotoxicity of the drug showing efficient cell killing at pM concentrations of the drug in U2OS-R1 cells. However, U2OS cells were also sensitive to the toxin after PCI. Binding experiments using confocal microscopy and Western blotting techniques indicate that FGF-SAP is taken up by cells through heparan sulfate proteoglycans (HSPGs) in U2OS cells. We further show that the cytotoxicity of FGF-SAP in U2OS cells was reduced when cells were co-treated with heparin to compete out binding to HSPG, demonstrating that the cytotoxic effect was due to internalization by HSPGs. We conclude that to prevent off-target effects of FGF-based toxins, it will be necessary to circumvent binding to HSPGs, for example by mutating the binding site of FGF2 to HSPGs.

Recent Advances of Cell Membrane Coated Nanoparticles in Treating Cardiovascular Disorders

Cardiovascular diseases (CVDs) are the leading cause of death worldwide, causing approximately 17.9 million deaths annually, an estimated 31% of all deaths, according to the WHO. CVDs are essentially rooted in atherosclerosis and are clinically classified into coronary heart disease, stroke and peripheral vascular disorders. Current clinical interventions include early diagnosis, the insertion of stents, and long-term preventive therapy. However, clinical diagnostic and therapeutic tools are subject to a number of limitations including, but not limited to, potential toxicity induced by contrast agents and unexpected bleeding caused by anti-platelet drugs. Nanomedicine has achieved great advancements in biomedical area. Among them, cell membrane coated nanoparticles, denoted as CMCNPs, have acquired enormous expectations due to their biomimetic properties. Such membrane coating technology not only helps avoid immune clearance, but also endows nanoparticles with diverse cellular and functional mimicry. In this review, we will describe the superiorities of CMCNPs in treating cardiovascular diseases and their potentials in optimizing current clinical managements.

Non-Traumatic Intramuscular Hip Hematoma in a Cirrhotic Patient With Hepatocellular Carcinoma and Portal Vein Thrombosis Treated With Sorafenib and Low Molecular Weight Heparin

Hepatocellular carcinoma (HCC) is a common neoplasm amongst cirrhotic patients and portal vein thrombosis (PVT) is an often found complication. Sorafenib and low molecular weight heparin (LMWH) are considered part of the gold-standard treatment of such patients. Spontaneous intramuscular hematomas of the limbs induced by these agents, as an adverse event, are generally rare. We present a 66-year-old male patient with liver cirrhosis, HCC and PVT treated with Sorafenib and LMWH who developed a non-traumatic hip hematoma. Simple elevation of the lower limb and blood-products infusion was successful in leading to resolution of the symptoms. As the popularity of these agents increases, healthcare providers need to be aware of such treatment adverse events.

The impact of CYP2C9 and VKORC1 genetic polymorphisms in anticoagulant therapy management after cardiac surgery with extracorporeal circulation

Extracorporeal circulation during cardiac surgery is characterized with increased risk for hypercoagulation because blood is exposed to foreign, nonendothelial cell surfaces. Thus, the usage of extracorporeal circulation is essentially not possible without anticoagulation. Open-heart surgery as well as many perioperative factors, such as acidosis, hypocalcemia, hypothermia, and hemodilution, might affect hemostasis and lead to coagulopathy and bleeding. A new insight into the effectiveness of anticoagulant therapy is applied to modify the dosing regimen with respect to the genetic CYP2C9 and VKORC1allelic variants. A systematic literature search was performed for VKORC1 and CYP2C9 and their association with coumarin anticoagulant therapy and bleeding risk in postoperative period of cardiac surgery with extracorporeal circulation.

Viscoelastic Haemostatic Assays in Cardiovascular Critical Care

The initiation and management of anticoagulation is a fundamental practice for a wide variety of indications in cardiovascular critical care, including the management of patients with acute MI, stroke prevention in patients with AF or mechanical valves, as well as the prevention of device thrombosis and thromboembolic events with the use of mechanical circulatory support and ventricular assist devices. The frequent use of antiplatelet and anticoagulation therapy, in addition to the presence of concomitant conditions that may lead to a propensity to bleed, such as renal and liver dysfunction, present unique challenges. The use of viscoelastic haemostatic assays provides an additional tool allowing clinicians to strike a delicate balance of attaining adequate anticoagulation while minimising the risk of bleeding complications. In this review, the authors discuss the role that viscoelastic haemostatic assay plays in cardiac populations (including cardiac surgery, heart transplantation, extracorporeal membrane oxygenation, acute coronary syndrome and left ventricular assist devices), and identify areas in need of further study.

Understanding the Interaction of Polyelectrolyte Architectures with Proteins and Biosystems

The counterions neutralizing the charges on polyelectrolytes such as DNA or heparin may dissociate in water and greatly influence the interaction of such polyelectrolytes with biomolecules, particularly proteins. In this Review we give an overview of studies on the interaction of proteins with polyelectrolytes and how this knowledge can be used for medical applications. Counterion release was identified as the main driving force for the binding of proteins to polyelectrolytes: Patches of positive charge become multivalent counterions of the polyelectrolyte and lead to the release of counterions from the polyelectrolyte and a concomitant increase in entropy. This is shown from investigations on the interaction of proteins with natural and synthetic polyelectrolytes. Special emphasis is paid to sulfated dendritic polyglycerols (dPGS). The Review demonstrates that we are moving to a better understanding of charge-charge interactions in systems of biological relevance. Research along these lines will aid and promote the design of synthetic polyelectrolytes for medical applications.

Exosite inhibition of ADAMTS-5 by a glycoconjugated arylsulfonamide

ADAMTS-5 is a major protease involved in the turnover of proteoglycans such as aggrecan and versican. Dysregulated aggrecanase activity of ADAMTS-5 has been directly linked to the etiology of osteoarthritis (OA). For this reason, ADAMTS-5 is a pharmaceutical target for the treatment of OA. ADAMTS-5 shares high structural and functional similarities with ADAMTS-4, which makes the design of selective inhibitors particularly challenging. Here we exploited the ADAMTS-5 binding capacity of β-N-acetyl-d-glucosamine to design a new class of sugar-based arylsulfonamides. Our most promising compound, 4b, is a non-zinc binding ADAMTS-5 inhibitor which showed high selectivity over ADAMTS-4. Docking calculations combined with molecular dynamics simulations demonstrated that 4b is a cross-domain inhibitor that targets the interface of the metalloproteinase and disintegrin-like domains. Furthermore, the interaction between 4b and the ADAMTS-5 Dis domain is mediated by hydrogen bonds between the sugar moiety and two lysine residues (K532 and K533). Targeted mutagenesis of these two residues confirmed their importance both for versicanase activity and inhibitor binding. This positively-charged cluster of ADAMTS-5 represents a previously unknown substrate-binding site (exosite) which is critical for substrate recognition and can therefore be targeted for the development of selective ADAMTS-5 inhibitors.

Serpins in Hemostasis as Therapeutic Targets for Bleeding or Thrombotic Disorders

Bleeding and thrombotic disorders result from imbalances in coagulation or fibrinolysis, respectively. Inhibitors from the serine protease inhibitor (serpin) family have a key role in regulating these physiological events, and thus stand out as potential therapeutic targets for modulating fibrin clot formation or dismantling. Here, we review the diversity of serpin-targeting strategies in the area of hemostasis, and detail the suggested use of modified serpins and serpin inhibitors (ranging from small-molecule drugs to antibodies) to treat or prevent bleeding or thrombosis.

S-Nitrosoglutathione-Based Nitric Oxide-Releasing Nanofibers Exhibit Dual Antimicrobial and Antithrombotic Activity for Biomedical Applications

The novel use of nanofibers as a physical barrier between blood and medical devices has allowed for modifiable, innovative surface coatings on devices ordinarily plagued by thrombosis, delayed healing, and chronic infection. In this study, the nitric oxide (NO) donor S-nitrosoglutathione (GSNO) is blended with the biodegradable polymers polyhydroxybutyrate (PHB) and polylactic acid (PLA) for the fabrication of hemocompatible, antibacterial nanofibers tailored for blood-contacting applications. Stress/strain behavior of different concentrations of PHB and PLA is recorded to optimize the mechanical properties of the nanofibers. Nanofibers incorporated with different concentrations of GSNO (10, 15, 20 wt%) are evaluated based on their NO-releasing kinetics. PLA/PHB + 20 wt% GSNO nanofibers display the greatest NO release over 72 h (0.4-1.5 × 10-10  mol mg-1 min-1 ). NO-releasing fibers successfully reduce viable adhered bacterial counts by ≈80% after 24 h of exposure to Staphylococcus aureus. NO-releasing nanofibers exposed to porcine plasma reduce platelet adhesion by 64.6% compared to control nanofibers. The nanofibers are found noncytotoxic (>95% viability) toward NIH/3T3 mouse fibroblasts, and 4',6-diamidino-2-phenylindole and phalloidin staining shows that fibroblasts cultured on NO-releasing fibers have improved cellular adhesion and functionality. Therefore, these novel NO-releasing nanofibers provide a safe antimicrobial and hemocompatible coating for blood-contacting medical devices.

Combination targeting of 'platelets + fibrin' enhances clot anchorage efficiency of nanoparticles for vascular drug delivery

Occlusive thrombosis is a central pathological event in heart attack, stroke, thromboembolism, etc. Therefore, pharmacological thrombolysis or anticoagulation is used for treating these diseases. However, systemic administration of such drugs causes hemorrhagic side-effects. Therefore, there is significant clinical interest in strategies for enhanced drug delivery to clots while minimizing systemic effects. One such strategy is by using drug-carrying nanoparticles surface-decorated with clot-binding ligands. Efforts in this area have focused on binding to singular targets in clots, e.g. platelets, fibrin, collagen, vWF or endothelium. Targeting vWF, collagen or endothelium maybe sub-optimal since in vivo these entities will be rapidly covered by platelets and leukocytes, and thus inaccessible for sufficient nanoparticle binding. In contrast, activated platelets and fibrin are majorly accessible for particle-binding, but their relative distribution in clots is highly heterogeneous. We hypothesized that combination-targeting of 'platelets + fibrin' will render higher clot-binding efficacy of nanoparticles, compared to targeting platelets or fibrin singularly. To test this, we utilized liposomes as model nanoparticles, decorated their surface with platelet-binding peptides (PBP) or fibrin-binding peptides (FBP) or combination (PBP + FBP) at controlled compositions, and evaluated their binding to human blood clots in vitro and in a mouse thrombosis model in vivo. In parallel, we developed a computational model of nanoparticle binding to single versus combination entities in clots. Our studies indicate that combination targeting of 'platelets + fibrin' enhances the clot-anchorage efficacy of nanoparticles while utilizing lower ligand densities, compared to targeting platelets or fibrin only. These findings provide important insights for vascular nanomedicine design.

Heparin-binding Peptides as Novel Therapies to Stop SARS-CoV-2 Cellular Entry and Infection

Heparan sulfate proteoglycans (HSPGs) are cell surface receptors that are involved in the cellular uptake of pathologic amyloid proteins and viruses, including the novel coronavirus; severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Heparin and heparan sulfate antagonize the binding of these pathogens to HSPGs and stop their cellular internalization, but the anticoagulant effect of these agents has been limiting their use in the treatment of viral infections. Heparin-binding peptides (HBPs) are suitable nonanticoagulant agents that are capable of antagonizing binding of heparin-binding pathogens to HSPGs. Here, we review and discuss the use of HBPs as viral uptake inhibitors and will address their benefits and limitations to treat viral infections. Furthermore, we will discuss a variant of these peptides that is in the clinic and can be considered as a novel therapy in coronavirus disease 2019 (COVID-19) infection. SIGNIFICANCE STATEMENT: The need to discover treatment modalities for COVID-19 is a necessity, and therapeutic interventions such as heparin-binding peptides (HBPs), which are used for other cases, can be beneficial based on their mechanisms of actions. In this paper, we have discussed the application of HBPs as viral uptake inhibitors in COVID-19 and explained possible mechanisms of actions and the therapeutic effects.

Therapeutic duplication of anticoagulants: a retrospective study of frequency and consequences in a tertiary referral hospital

BACKGROUND

Anticoagulants are commonly prescribed in medical practices and could be of significant harm in the case of medication errors. We conducted a retrospective observational study to determine the frequency and consequences of the therapeutic duplication of anticoagulants (TDA). As a secondary objective, we aimed to determine the characteristics of the population in which TDA occurs.

METHODS

We conducted a retrospective observational study among admitted patients who concomitantly received at least two anticoagulants from August 2017 to August 2018.

RESULTS

A total of 107 patients with TDA are included in the research. The patients with TDA have a mean age of 73. The TDA population has a high rate of associated comorbidities with 69% of patients having arterial hypertonia, 40% with chronic kidney disease, 26% with a history of malignancy, and 20.5% with a history of stroke. More than 65% of patients were under anticoagulation before admission, mostly due to atrial fibrillation. The TDA occurred in more than 95% of cases in the first week or the last week of hospitalization. Patients had a high risk of bleeding prior to the TDA-event with about 62.5% of TDA patients having a HAS-BLED score at least 3. A total of 8 patients showed a significant Hemoglobin (Hb)-drop of at least 10 g/L within 24 h after TDA-event. Two patients had a new or worsened hematuria following TDA-event.

CONCLUSION

TDA occurred in 0.8% of patients who were under anticoagulation and in 6.7% of patients who received direct oral anticoagulants (DOACs). TDA led in about 7.4% of cases to hemoglobin-relevant bleeding. The old patients with significant comorbidities and a high HAS-BLED score were mainly affected. The female gender and presence of anemia independently predicted the occurrence of bleeding following TDA.

A Review on the Use of Reversal Agents of Direct Oral Anticogulant Drugs in Case of Gastrointestinal Bleeding

BACKGROUND

Major bleeding is a life-threatening condition and a medical emergency with high mortality risk. It is often the complication of anticoagulant's intake. Anticoagulants are commonly used for the prevention and treatment of thrombotic events. The standard therapy with vitamin K antagonist (warfarin) has been frequently replaced by direct oral anticoagulants (DOACs). The latter agents (rivaroxaban, apixaban, edoxaban, dabigatran, and betrixaban) showed better efficacy and safety compared to standard warfarin treatment and they are recommended for the reduction of ischemic stroke. Literature data reported a high risk of gastrointestinal bleeding with DOACs, in particular with dabigatran and rivaroxaban. In case of life-threatening gastrointestinal bleeding, these patients could benefit from the use of reversal agents.

METHODS

We performed an electronic search on PUBMED of the literature concerning reversal agents for DOACs and gastrointestinal bleeding in the Emergency Department from 2004 to 2020.

AIM

This review summarizes the current evidence about three reversal agents idarucizumab, andexanet alfa and ciraparantag, and the use of the first two in the emergency setting in patients with active major bleeding or who need urgent surgery which physicians indicate for a better management approach in order to increase patient's safety.

CONCLUSION

Although these agents have been marketed for five years (idarucizumab) and two years (andexanet alfa) respectively, and despite guidelines considering antidotes as first-line agents in treating life-threatening hemorrhage when available, these antidotes seem to gain access very slowly in the clinical practice. Cost, logistical aspects and need for plasma level determination of DOAC for an accurate therapeutic use probably have an impact on this phenomenon.. An expert multidisciplinary bleeding team should be established so as to implement international guidelines based on local resources and organization.

The Impact of Thromboelastography on Blood Transfusion Policy in Adult Cardiac Surgery-A Retrospective Observational Study from Eastern India

This study was conducted to determine the impact of thromboelastography (TEG) on blood transfusion policy regarding utilization and preparation of cryoprecipitate in adult cardiac surgery. The differences in total transfusion requirement, length of postoperative ICU stay and 24 h mortality were also studied after introduction of TEG in transfusion protocol. It was a retrospective, single-center, observational study conducted in adult patients underwent cardiac surgery from April 2008 to March 2016. Two thousand patients underwent surgery when TEG was used compared with 1000 control patients before availability of TEG. Significantly more patients in the TEG group versus the control group received cryoprecipitate (41 vs. 7%; p < 0.05), while fewer received a transfusion (60 vs. 87.5%; p < 0.05). Significant increase in cryoprecipitate preparation was observed after introduction of TEG. Patients underwent surgery in TEG group showed substantial reduction in administration of PRBC (2.1 vs. 3.5 U; p < 0.05); FFP (2.4 vs. 3.8 U; p < 0.05) and platelets (1.1 vs. 2.7 U; p < 0.05) compared to control group without compromising the length of ICU stay or postoperative mortality. A TEG-guided approach in adult patients undergoing cardiac surgery may increase the use of cryoprecipitate, while decreasing the overall requirement of blood transfusion.