Potential Therapeutic Roles for Direct Factor Xa Inhibitors in Coronavirus Infections.

Human factor Xa (FXa) is a serine protease of the common coagulation pathway. FXa is known to activate prothrombin to thrombin, which eventually leads to the formation of cross-linked blood clots. While this process is important in maintaining hemostasis, excessive thrombin generation results in a host of thrombotic conditions. FXa has also been linked to inflammation via protease-activated receptors. Together, coagulopathy and inflammation have been implicated in the pathogenesis of viral infections, including the current coronavirus pandemic. Direct FXa inhibitors have been shown to possess anti-inflammatory and antiviral effects, in addition to their established anticoagulant activity. This review summarizes the pharmacological activities of direct FXa inhibitors, their pharmacokinetics, potential drug-drug interactions and adverse effects, and the details of clinical trials involving direct FXa inhibitors in coronavirus disease 2019 (COVID-19) patients.

Pharmacologic Thromboprophylaxis and Thrombosis in Hospitalized Patients with COVID-19: A Pooled Analysis.

BACKGROUND: Coronavirus disease 2019 (COVID-19) increases thrombosis in hospitalized patients prompting adoption of different thromboprophylaxis strategies. Safety and efficacy of escalated-dose pharmacologic thromboprophylaxis are not established. OBJECTIVES: To determine the pooled incidence of thrombosis/bleeding in hospitalized patients with COVID-19 for standard-dose, intermediate-dose, therapeutic anticoagulation, and no pharmacologic thromboprophylaxis. METHODS: MEDLINE, EMBASE, and Cochrane CENTRAL were searched up to August 29, 2020 for studies reporting pharmacologic thromboprophylaxis and thrombosis or bleeding. Pooled event rates were calculated using a random-effects model. RESULTS: Thirty-five observational studies were included. The pooled incidence rates of total venous thromboembolism (N = 4,685) were: no prophylaxis 41.9% (95% confidence interval [CI]: 28.1-57.2, I 2 = 76%), standard-dose prophylaxis 19.8% (95% CI: 13.2-28.6, I 2 = 95%), intermediate-dose prophylaxis 11.9% (95% CI: 4.3-28.6, I 2 = 91%), and therapeutic-dose anticoagulants 10.5% (95% CI: 4.2-23.8, I 2 = 82%, p = 0.003). The pooled incidence rates of arterial thrombosis (N = 1,464) were: no prophylaxis 11.3% (95% CI: 5.2-23.0, I 2 = 0%), standard-dose prophylaxis 2.5% (95% CI: 1.4-4.3, I 2 = 45%), intermediate-dose prophylaxis 2.1% (95% CI: 0.5-7.7, I 2 = 45%), and therapeutic-dose anticoagulants 1.3% (95% CI: 0.2-8.8, I 2 = 0, p = 0.009). The pooled bleeding event rates (N = 6,393) were nonsignificantly higher in therapeutic-dose anticoagulants compared with standard-dose prophylaxis, (6.3 vs. 1.7%, p = 0.083). CONCLUSION: Thrombosis rates were lower in hospitalized COVID-19 patients who received pharmacologic thromboprophylaxis. Thrombosis and bleeding rates for patients receiving intermediate-dose thromboprophylaxis or therapeutic anticoagulation were similar to those who received standard-dose pharmacologic thromboprophylaxis.

Contribution value of coagulation abnormalities in COVID-19 prognosis: a bright perspective on the laboratory pattern of patients with coronavirus disease 2019.

OBJECTIVE: From the beginning of the novel coronavirus infection (COVID-19) pandemic in the world, much efforts have been accomplished to explain a precise clinical feature for the disease and to find the best therapeutic approach for the patients. Although coagulation abnormalities have found in novel coronavirus infection (COVID-19) patients, still little is known about the association between the disease and changes in coagulation parameters. Our purpose is to evaluate the differences between the coagulation parameters between COVID-19 patients and healthy counterparts. PATIENTS AND METHODS: 63 patients with confirmed COVID-19 infection were admitted to the present study. We evaluated coagulation value in these patients and in 40 healthy individuals. RESULTS: We found that although there was no significant difference between PT and PTT values in patients and healthy counterparts, the fibrinogen values in patients were higher than the control group (p < 0.05). Moreover, the values of fibrin/fibrinogen degradation products (FDP) and D-dimer in all COVID-19 cases were considerably higher than those in control people (p < 0.05). Of note, FDP and D-dimer in patients with regular COVID-19 infection were lower than patients with severe forms. CONCLUSIONS: It seems that the conduction of routine blood coagulation test could be a beneficial supplementary approach for early diagnosis of COVID-19. In addition, our study shed more light on the therapeutic value of anti-coagulant-based treatment for COVID-19 patients, especially for those with severe type of the disease.

Heparin in COVID-19 Patients Is Associated with Reduced In-Hospital Mortality: The Multicenter Italian CORIST Study.

INTRODUCTION: A hypercoagulable condition was described in patients with coronavirus disease 2019 (COVID-19) and proposed as a possible pathogenic mechanism contributing to disease progression and lethality. AIM: We evaluated if in-hospital administration of heparin improved survival in a large cohort of Italian COVID-19 patients. METHODS: In a retrospective observational study, 2,574 unselected patients hospitalized in 30 clinical centers in Italy from February 19, 2020 to June 5, 2020 with laboratory-confirmed severe acute respiratory syndrome coronavirus-2 infection were analyzed. The primary endpoint in a time-to event analysis was in-hospital death, comparing patients who received heparin (low-molecular-weight heparin [LMWH] or unfractionated heparin [UFH]) with patients who did not. We used multivariable Cox proportional-hazards regression models with inverse probability for treatment weighting by propensity scores. RESULTS: Out of 2,574 COVID-19 patients, 70.1% received heparin. LMWH was largely the most used formulation (99.5%). Death rates for patients receiving heparin or not were 7.4 and 14.0 per 1,000 person-days, respectively. After adjustment for propensity scores, we found a 40% lower risk of death in patients receiving heparin (hazard ratio = 0.60; 95% confidence interval: 0.49-0.74; E-value = 2.04). This association was particularly evident in patients with a higher severity of disease or strong coagulation activation. CONCLUSION: In-hospital heparin treatment was associated with a lower mortality, particularly in severely ill COVID-19 patients and in those with strong coagulation activation. The results from randomized clinical trials are eagerly awaited to provide clear-cut recommendations.

Beneficial Effects of Intermediate Dosage of Anticoagulation Treatment on the Prognosis of Hospitalized COVID-19 Patients: The ETHRA Study.

BACKGROUND/AIM: To investigate the efficacy (prognosis, coagulation/inflammation biomarkers) and safety (bleeding events) of different anticoagulation dosages in COVID-19 inpatients. PATIENTS AND METHODS: COVID-19 inpatients (Athens, Greece) were included. The "Enhanced dose THRomboprophylaxis in Admissions (ETHRA)" protocol was applied in certain Departments, suggesting the use of intermediate anticoagulation dosage. The primary endpoint was a composite of intubation/venous thromboembolism/death. Inflammation/coagulation parameters were assessed. RESULTS: Among 127 admissions, 95 fulfilled the inclusion criteria. Twenty-one events (4 deaths, 17 intubations) were observed. Regression analysis demonstrated significant reduction of events with intermediate or therapeutic dosage [HR=0.16 (95%CI=0.05-0.52) p=0.002; HR=0.17 (0.04-0.71) p=0.015, respectively]. D-Dimer values were higher in those who met the composite endpoint. Intermediate dosage treatment was associated with decreased values of ferritin. Three patients (3%) had minor hemorrhagic complications. CONCLUSION: Anticoagulation treatment (particularly intermediate dosage) appears to have positive impact on COVID-19 inpatients' prognosis by inhibiting both coagulation and inflammatory cascades.

The Association of Low Molecular Weight Heparin Use and In-hospital Mortality Among Patients Hospitalized with COVID-19.

PURPOSE: To determine the association between low molecular weight heparin (LMWH) use and mortality in hospitalized COVID-19 patients. METHODS: We conducted a retrospective study of patients consecutively enrolled from two major academic hospitals exclusively for COVID-19 in Wuhan, China, from January 26, 2020, to March 26, 2020. The primary outcome was adjusted in-hospital mortality in the LMWH group compared with the non-LMWH group using the propensity score. RESULTS: Overall, 525 patients with COVID-19 enrolled with a median age of 64 years (IQR 19), and 49.33% men. Among these, 120 (22.86%) were treated with LMWH. Compared with the non-LMWH group, the LMWH group was more likely to be older and male; had a history of hypertension, diabetes, coronary heart disease (CHD), or stroke; and had more severe COVID-19 parameters such as higher inflammatory cytokines or D-dimer. Compared with non-LMWH group, LMWH group had a higher unadjusted in-hospital mortality rate (21.70% vs. 11.10%; p = 0.004), but a lower adjusted mortality risk (adjusted odds ratio [OR], 0.20; 95% CI, 0.09-0.46). A propensity score-weighting analysis demonstrated similar findings (adjusted OR, 0.18; 95% CI, 0.10-0.30). Subgroup analysis showed a significant survival benefit among those who were severely (adjusted OR, 0.07; 95% CI, 0.02-0.23) and critically ill (adjusted OR, 0.32; 95% CI, 0.15-0.65), as well as among the elderly patients' age > 65, IL-6 > 10 times upper limit level, and D-dimer > 5 times upper limit level. CONCLUSIONS: Among hospitalized COVID-19 patients, LMWH use was associated with lower all-cause in-hospital mortality than non-LMWH users. The survival benefit was particularly significant among more severely ill patients.

Therapeutic dosing of low-molecular-weight heparin may decrease mortality in patients with severe COVID-19 infection.

BACKGROUND: Venous thromboembolism or extensive thrombosis is relatively common in patients with severe COVID-19 infection and has been associated with increased mortality. During the current COVID-19 pandemic, several prophylactic doses and types of low-molecular-weight heparin (LMWH) are being used worldwide; however, there are no high-quality studies or recommendations for an optimal prophylactic LMWH dose. OBJECTIVES: Investigate the relationship between coagulation parameters and the LMWH dose, and mortality and ICU admission in hospitalized patients with severe COVID-19 pneumonia. DESIGN: Retrospective. SETTING: Tertiary care hospital. PATIENTS AND METHODS: Data on clinical features, coagulation parameters and anticoagulant medications of inpatients with severe COVID-19 were collected for the period between 11 March 2020 and 31 April 2020. MAIN OUTCOME MEASURES: Mortality and ICU admission for prophylactic dose LMWH (0.5 mg/kg twice daily) and therapeutic dose LMWH (1 mg/kg twice daily). SAMPLE SIZE: 154 cases. RESULTS: Ninety-eight (63.6%) patients were treated with the LMWH prophylactic dose and 56 (36.4%) patients were treated with the therapeutic dose. Forty-four (44.9%) of 98 patients using the prophylactic dose LMWH died, while 10 (17.9%) of 56 patients using the therapeutic dose LMWH died (P=.001). Mortality was 6.4-fold higher in the prophylactic dose LMWH users than in the therapeutic dose LMWH users (OR=6.5, 95% CI: 2.4-17.6, P<.001). CONCLUSIONS: Therapeutic dosing of LMWH may decrease mortality in patients with severe COVID-19 infected pneumonia. More aggressive thromboprophylaxis regimens using higher doses of heparin should be evaluated in prospective studies. LIMITATIONS: Lack of information about bleeding complications. LMWH was not compared with other anticoagulant therapies. There was no comparison between our two groups on the APACHE score. Used different doses of LMWH in different clinics in our hospital. Single-center, retrospective study. CONFLICT OF INTEREST: None.

Hyperthrombotic Milieu in COVID-19 Patients.

COVID-19 infection has protean systemic manifestations. Experience from previous coronavirus outbreaks, including the current SARS-CoV-2, has shown an augmented risk of thrombosis of both macrovasculature and microvasculature. The former involves both arterial and venous beds manifesting as stroke, acute coronary syndrome and venous thromboembolic events. The microvascular thrombosis is an underappreciated complication of SARS-CoV-2 infection with profound implications on the development of multisystem organ failure. The telltale signs of perpetual on-going coagulation and fibrinolytic cascades underscore the presence of diffuse endothelial damage in the patients with COVID-19. These parameters serve as strong predictors of mortality. While summarizing the alterations of various components of thrombosis in patients with COVID-19, this review points to the emerging evidence that implicates the prominent role of the extrinsic coagulation cascade in COVID-19-related coagulopathy. These mechanisms are triggered by widespread endothelial cell damage (endotheliopathy), the dominant driver of macro- and micro-vascular thrombosis in these patients. We also summarize other mediators of thrombosis, clinically relevant nuances such as the occurrence of thromboembolic events despite thromboprophylaxis (breakthrough thrombosis), current understanding of systemic anticoagulation therapy and its risk-benefit ratio. We conclude by emphasizing a need to probe COVID-19-specific mechanisms of thrombosis to develop better risk markers and safer therapeutic targets.

Protease-activated receptor 1 as a potential therapeutic target for COVID-19.

Acute respiratory disease caused by a novel coronavirus (SARS-CoV-2) has spread all over the world, since its discovery in 2019, Wuhan, China. This disease is called COVID-19 and already killed over 1 million people worldwide. The clinical symptoms include fever, dry cough, dyspnea, headache, dizziness, generalized weakness, vomiting, and diarrhea. Unfortunately, so far, there is no validated vaccine, and its management consists mainly of supportive care. Venous thrombosis and pulmonary embolism are highly prevalent in patients suffering from severe COVID-19. In fact, a prothrombotic state seems to be present in most fatal cases of the disease. SARS-CoV-2 leads to the production of proinflammatory cytokines, causing immune-mediated tissue damage, disruption of the endothelial barrier, and uncontrolled thrombogenesis. Thrombin is the key regulator of coagulation and fibrin formation. In severe COVID-19, a dysfunctional of physiological anticoagulant mechanisms leads to a progressive increase of thrombin activity, which is associated with acute respiratory distress syndrome development and a poor prognosis. Protease-activated receptor type 1 (PAR1) is the main thrombin receptor and may represent an essential link between coagulation and inflammation in the pathophysiology of COVID-19. In this review, we discuss the potential role of PAR1 inhibition and regulation in COVID-19 treatment.

Anticoagulation in COVID-19: Effect of Enoxaparin, Heparin, and Apixaban on Mortality.

BACKGROUND: Mortality in coronavirus disease of 2019 (COVID-19) is associated with increases in prothrombotic parameters, particularly D-dimer levels. Anticoagulation has been proposed as therapy to decrease mortality, often adjusted for illness severity. OBJECTIVE: We wanted to investigate whether anticoagulation improves survival in COVID-19 and if this improvement in survival is associated with disease severity. METHODS: This is a cohort study simulating an intention-to-treat clinical trial, by analyzing the effect on mortality of anticoagulation therapy chosen in the first 48 hours of hospitalization. We analyzed 3,625 COVID-19+ inpatients, controlling for age, gender, glomerular filtration rate, oxygen saturation, ventilation requirement, intensive care unit admission, and time period, all determined during the first 48 hours. RESULTS: Adjusted logistic regression analyses demonstrated a significant decrease in mortality with prophylactic use of apixaban (odds ratio [OR] 0.46, p = 0.001) and enoxaparin (OR = 0.49, p = 0.001). Therapeutic apixaban was also associated with decreased mortality (OR 0.57, p = 0.006) but was not more beneficial than prophylactic use when analyzed over the entire cohort or within D-dimer stratified categories. Higher D-dimer levels were associated with increased mortality (p < 0.0001). When adjusted for these same comorbidities within D-dimer strata, patients with D-dimer levels < 1 µg/mL did not appear to benefit from anticoagulation while patients with D-dimer levels > 10 µg/mL derived the most benefit. There was no increase in transfusion requirement with any of the anticoagulants used. CONCLUSION: We conclude that COVID-19+ patients with moderate or severe illness benefit from anticoagulation and that apixaban has similar efficacy to enoxaparin in decreasing mortality in this disease.

The Use of Therapeutic-Dose Anticoagulation and Its Effect on Mortality in Patients With COVID-19: A Systematic Review.

The incidence of venous thromboembolism (VTE) events in patients with COVID-19 treated with a standard thromboprophylaxis dose of anticoagulants remains high. We conducted a systematic review in order to explore the association between therapeutic-dose anticoagulation and its effect on mortality in patients with COVID-19. A systematic search was carried out using the electronic databases of PubMed, EuropePMC, and the Cochrane Central Database, using specific keywords. All articles that fulfilled the inclusion criteria were included in the qualitative analysis. There were 8 observational studies included in the final qualitative analysis. Quality assessment using the Newcastle-Ottawa Scale (NOS) showed a mean score of 7.5 ± 1.06, indicating moderate to high quality of the studies. Three retrospective cohort studies reported a reduction in the mortality rate, while 6 other studies showed no mortality benefits among patients with COVID-19 treated with therapeutic-dose anticoagulation. There was a slight tendency toward a reduction in the mortality rate among mechanically-ventilated patients with COVID-19 receiving therapeutic-dose anticoagulation. Bleeding events and thrombotic complications among patients receiving therapeutic-dose anticoagulation were reported in 3 studies. Although it is too soon to draw any conclusions, this systematic review draws attention to current evidence regarding the association between therapeutic-dose anticoagulation and its effect on mortality in patients with COVID-19.

Thrombotic Complications in Patients with COVID-19: Pathophysiological Mechanisms, Diagnosis, and Treatment.

INTRODUCTION: Emerging evidence points to an association between severe clinical presentation of COVID-19 and increased risk of thromboembolism. One-third of patients hospitalized due to severe COVID-19 develops macrovascular thrombotic complications, including venous thromboembolism, myocardial injury/infarction and stroke. Concurrently, the autopsy series indicate multiorgan damage pattern consistent with microvascular injury. PROPHYLAXIS, DIAGNOSIS AND TREATMENT: COVID-19 associated coagulopathy has distinct features, including markedly elevated D-dimers concentration with nearly normal activated partial thromboplastin time, prothrombin time and platelet count. The diagnosis may be challenging due to overlapping features between pulmonary embolism and severe COVID-19 disease, such as dyspnoea, high concentration of D-dimers, right ventricle with dysfunction or enlargement, and acute respiratory distress syndrome. Both macro- and microvascular complications are associated with an increased risk of in-hospital mortality. Therefore, early recognition of coagulation abnormalities among hospitalized COVID-19 patients are critical measures to identify patients with poor prognosis, guide antithrombotic prophylaxis or treatment, and improve patients' clinical outcomes. RECOMMENDATIONS FOR CLINICIANS: Most of the guidelines and consensus documents published on behalf of professional societies focused on thrombosis and hemostasis advocate the use of anticoagulants in all patients hospitalized with COVID-19, as well as 2-6 weeks post hospital discharge in the absence of contraindications. However, since there is no guidance for deciding the intensity and duration of anticoagulation, the decision-making process should be made in individual-case basis. CONCLUSIONS: Here, we review the mechanistic relationships between inflammation and thrombosis, discuss the macrovascular and microvascular complications and summarize the prophylaxis, diagnosis and treatment of thromboembolism in patients affected by COVID-19.

Comparative Anticoagulant and Thrombin Generation Inhibitory Profile of Heparin, Sulodexide and Its Components.

INTRODUCTION: Sulodexide represents a mixture of fast-moving heparin (FMH) and dermatan sulfate (DS) and has been used for the management of venous diseases such as DVT and related disorders. The purpose of this study is to compare sulodexide and its components with unfractionated heparin (UFH) to determine its suitability for the indications in which UFH is used. MATERIALS AND METHOD: Active pharmaceutical ingredients (API) versions of sulodexide, FMH and DS were obtained from Alfasigma. API versions of UFH were obtained from Medefil Inc. Normal human citrated plasma was obtained from blood bank of the Loyola University Medical Center. Each of the individual agents were supplemented in plasma at a graded concentration of 0.0-10 µg/mL. Clotting assays (PiCT, aPTT, PT and TT), anti-Xa and anti-IIa and thrombin generation studies were carried out. Results were compiled as mean ± SD of 3 individual determination. RESULT: In the clot based (PiCT, aPTT and TT), anti-Xa and IIa assays, both the UFH and FMH produced stronger activities in these assays followed by sulodexide. DS did not show any anticoagulant activity. In the thrombin generation assay, FMH and UFH produced comparable inhibition of thrombin generation as measured by various parameters. Sulodexide was slightly weaker in this assay, whereas DS produced relatively weaker effects. CONCLUSION: In comparison to sulodexide, both UFH and FMH exhibit comparable anticoagulant activity despite differences in their molecular weight. These results suggest that sulodexide can be developed as a parenteral anticoagulant for indications in which UFH is used.

COVID-19 coagulopathy and thrombosis: Analysis of hospital protocols in response to the rapidly evolving pandemic.

As the Coronavirus disease 2019 (COVID-19) pandemic spread to the US, so too did descriptions of an associated coagulopathy and thrombotic complications. Hospitals created institutional protocols for inpatient management of COVID-19 coagulopathy and thrombosis in response to this developing data. We collected and analyzed protocols from 21 US academic medical centers developed between January and May 2020. We found greatest consensus on recommendations for heparin-based pharmacologic venous thromboembolism (VTE) prophylaxis in COVID-19 patients without contraindications. Protocols differed regarding incorporation of D-dimer tests, dosing of VTE prophylaxis, indications for post-discharge pharmacologic VTE prophylaxis, how to evaluate for VTE, and the use of empiric therapeutic anticoagulation. These findings support ongoing efforts to establish international, evidence-based guidelines.