Anti Xa activity after high dose LMWH thrombosis prophylaxis in covid 19 patients at the intensive care unit

Large variation in anti-factor Xa levels with nadroparin as thromboprophylaxis in COVID-19 and non-COVID-19 critically ill patients

PURPOSE

Critically ill COVID-19 and non-COVID-19 patients receive thromboprophylaxis with the LMWH nadroparin. Whether a standard dosage is adequate in attaining the target anti-FXa levels (0.20-0.50 IU/ml) in these groups is unknown.

METHODS

This study was a prospective, observational study in the ICU of a large general teaching hospital in the Netherlands. COVID-19 and non-COVID-19 patients admitted to the ICU who received LMWH in a prophylactic dosage of 2850 IU, 5700 IU or 11400 IU subcutaneously were eligible for the study. Anti-FXa levels were determined 4 h after administration. Relevant laboratory parameters, prespecified co-variates and clinical data were extracted from the electronic health record system. The primary goal was to evaluate anti-FXa levels in critically ill patients on a prophylactic dosage of nadroparin. The second goal was to investigate whether covariates had an influence on anti-FXa levels.

RESULTS

A total of 62 patients were included in the analysis. In the COVID-19 group and non-COVID-19 group, 29 (96%) and 12 patients (38%) reached anti-FXa levels above 0.20 IU/ml, respectively. In the non-COVID-19 group, 63% of the patients had anti-FXA levels below the target range. When adjusted for nadroparin dosage a significant relation was found between body weight and the anti-FXa level (p = 0.013).

CONCLUSION

A standard nadroparin dosage of 2850 IU sc in the critically ill patient is not sufficient to attain target anti-FXa levels in the majority of the studied patient group. We suggest a standard higher dosage in combination with body-weight dependent dosing as it leads to better exposure to nadroparin.

CLINICAL TRIALS REGISTRATION

Retrospectively registered, ClinicalTrials.gov ID NTC 05926518 g, date of registration 06/01/23, unique ID 2020/1725.

Correlation between heparin anti-Xa activity and thromboelastography in adult critically ill COVID-19 patients

STUDY OBJECTIVE

Severe coronavirus disease 2019 (COVID-19) increases the risk of thrombotic complications with unfractionated heparin (UFH) as a commonly used agent in managing venous thromboembolism (VTE). The optimal anticoagulation intensity and monitoring parameters in intensive care unit (ICU) COVID-19 patients remains controversial. The primary study aim was to evaluate the relationship between anti-Xa and thromboelastography (TEG) reaction (R) time in patients with severe COVID-19 receiving therapeutic UFH infusions.

DESIGN

Single-center, retrospective study conducted over a 15-month period (2020-2021).

SETTING

Academic medical center (Banner University Medical Center Phoenix).

PATIENTS

Adult patients with severe COVID-19 administered therapeutic UFH infusions with one or more corresponding TEG, and anti-Xa assessments drawn within ≤2 hours of each other were included. The primary end point was the correlation between anti-Xa and TEG R time. Secondary aims were to describe the correlation between activated partial thromboplastin time (aPTT) and TEG R time, as well as clinical outcomes. Pearson's coefficient was used to evaluate the correlation using a kappa measure of agreement.

Coagulopathy and thromboembolic events a pathogenic mechanism of COVID-19 associated with mortality: An updated review

During 2019, the SARS-CoV-2 emerged from China, and during months, COVID-19 spread in many countries around the world. The expanding data about pathogenesis of this virus could elucidate the exact mechanism by which COVID-19 caused death in humans. One of the pathogenic mechanisms of this disease is coagulation. Coagulation disorders that affect both venous and arterial systems occur in patients with COVID-19. The possible mechanism involved in the coagulation could be excessive inflammation induced by SARS-CoV-2. However, it is not yet clear well how SARS-CoV-2 promotes coagulopathy. However, some factors, such as pulmonary endothelial cell damage and some anticoagulant system disorders, are assumed to have an important role. In this study, we assessed conducted studies about COVID-19-induced coagulopathy to obtain clearer vision of the wide range of manifestations and possible pathogenesis mechanisms.

Low and Highly Variable Exposure to Prophylactic LMWH Nadroparin in Critically Ill Patients: Back to the Drawing Board for Prophylactic Dosing?

BACKGROUND AND OBJECTIVE

Low-molecular-weight heparins are routinely administered to patients in the intensive care unit to prevent venous thromboembolisms. There is considerable evidence that low-molecular-weight heparin doses should be personalised based on anti-Xa levels, but pharmacokinetic data in intensive care unit patients are lacking. This study aimed to characterise the pharmacokinetics and associated variability of the low-molecular-weight heparin nadroparin in critically ill patients.

METHODS

Critically ill adult patients who were admitted to the intensive care unit and received nadroparin for prophylaxis of venous thromboembolism were included in a study. Population pharmacokinetic analysis was performed by means of parametric non-linear mixed-effects modelling (NONMEM).

RESULTS

A total of 30 patients were enrolled with 12 patients undergoing continuous veno-venous hemodialysis and 18 patients not undergoing continuous veno-venous hemodialysis. Very high variability in pharmacokinetics was observed with an inter-individual variability in the volume of distribution of 63.7% (95% confidence interval 46.5-90.6), clearance of 166% (95% confidence interval 84.7-280) and relative bioavailability of 40.2% (95% confidence interval 29.5-52.6). We found that standard doses of 2850 IE and 5700 IE of nadroparin resulted in sub-prophylactic exposure in critically ill patients.

CONCLUSIONS

Low exposure and highly variable pharmacokinetics of nadroparin were observed in intensive care unit patients treated with a prophylactic dose. It can be debated whether nadroparin is currently dosed optimally in intensive care unit patients and our findings encourage the investigation of higher and tailored dosing of nadroparin in the critically ill.

The efficacy of low molecular weight heparin is reduced in COVID-19

BACKGROUND

A significant degree of mortality and morbidity in COVID-19 is through thromboembolic complications, only partially mitigated by anticoagulant therapy. Reliable markers of infection severity are not fully established.

OBJECTIVES

This study investigated whether visco-elastic biomarkers predict disease severity on presentation to the Emergency Department (ED) and how they measure response to anticoagulationMETHODS:Patients testing positive for COVID-19 at a large University Teaching Hospital ED were recruited at presentation. Multiple blood samples were taken throughout hospital admission to monitor disease progression with end outcome recorded. Visco-elastic markers, fractal dimension (df) and Time to Gel Point (TGP) which measure the properties of the incipient clot were compared in patients with and without anticoagulation by Low Molecular Weight Heparin (LMWH).

RESULTS

TGP and df did not predict severity of infection with COVID-19. Although LMWH prolonged TGP, there was no change in df indicating LMWH did not change clot microstructure.

CONCLUSIONS

Therapeutic efficacy of LMWH appears blunted in COVID-19 infection. This may be due to the inflammatory state creating a resistance to LMWH activity, which may explain why LMWH appears less effective in COVID-19 compared to other disease states. COVID-19 was not predicted by visco-elastic testing at the time of ED presentation.

Population pharmacokinetics of nadroparin for thromboprophylaxis in COVID-19 intensive care unit patients

AIMS

Nadroparin is administered to COVID-19 intensive care unit (ICU) patients as thromboprophylaxis. Despite existing population pharmacokinetic (PK) models for nadroparin in literature, the population PK of nadroparin in COVID-19 ICU patients is unknown. Moreover, optimal dosing regimens achieving anti-Xa target levels (0.3-0.7 IU/mL) are unknown. Therefore, a population PK analysis was conducted to investigate different dosing regimens of nadroparin in COVID-19 ICU patients.

METHODS

Anti-Xa levels (n = 280) from COVID-19 ICU patients (n = 65) receiving twice daily (BID) 5700 IU of subcutaneous nadroparin were collected to perform a population PK analysis with NONMEM v7.4.1. Using Monte Carlo simulations (n = 1000), predefined dosing regimens were evaluated.

RESULTS

A 1-compartment model with an absorption compartment adequately described the measured anti-Xa levels with interindividual variability estimated for clearance (CL). Inflammation parameters C-reactive protein, D-dimer and estimated glomerular filtration rate based on the Chronic Kidney Disease Epidemiology Collaboration equation allowed to explain the interindividual variability of CL. Moreover, CL was decreased in patients receiving corticosteroids (22.5%) and vasopressors (25.1%). Monte Carlo simulations demonstrated that 5700 IU BID was the most optimal dosing regimen of the simulated regimens for achieving prespecified steady-state t = 4 h anti-Xa levels with 56.7% on target (0.3-0.7 IU/mL).

CONCLUSION

In our study, clearance of nadroparin is associated with an increase in inflammation parameters, use of corticosteroids, vasopression and renal clearance in critically ill patients. Furthermore, of the simulated regimens, targeted anti-Xa levels were most adequately achieved with a dosing regimen of 5700 IU BID. Future studies are needed to elucidate the underlying mechanisms of found covariate relationships.

Assessment and Monitoring of Coagulation in Patients with COVID-19: A Review of Current Literature

Coagulation abnormalities are common in patients with COVID-19 and associated with high morbidity and mortality. It became a daily challenge to navigate through these abnormal laboratory findings and deliver the best possible treatment to the patients. The unique character of COVID-19-induced coagulopathy necessitates not only a dynamic follow-up of the patients in terms of hemostatic findings but also the introduction of new diagnostic methods to determine the overall function of the coagulation system in real time. After the recognition of the high risk of thromboembolism in COVID-19, several professional societies published their recommendations regarding anticoagulation in patients with COVID-19. This review summarizes common hemostatic findings in COVID-19 patients and presents the societal recommendations regarding the use of coagulation laboratory findings in clinical decision-making. Although several studies have investigated coagulation parameters in patients with COVID-19, the methodological shortcomings of published studies as well as the differences in employed anticoagulation regimens that have changed over time, depending on national and international guidelines, limit the applicability of these findings in other clinical settings. Accordingly, evidence-based recommendations for diagnostics during acute COVID-19 infection are still lacking. Future studies should verify the role of coagulation parameters as well as viscoelastic methods in the management of patients with COVID-19.

Anti-factor Xa Activity Is Not Associated With Venous Thromboembolism in Critically Ill Patients Receiving Enoxaparin for Thromboprophylaxis: A Retrospective Observational Study

Background

Anti-factor Xa activity has been suggested as a surrogate parameter for judging the effectiveness of pharmacological thromboprophylaxis with low molecular weight heparins in critically ill patients. However, this practice is not supported by evidence associating low anti-factor Xa activity with venous thromboembolism.

Methods

We performed a retrospective observational study including 1,352 critically ill patients admitted to 6 intensive care units of the Medical University of Vienna, Austria between 01/2015 and 12/2018. Included patients received prophylactically dosed enoxaparin (≤100 IU/kg body weight per day). We analyzed median peak, 12-h trough and 24-h trough anti-factor Xa activity per patient and compared anti-factor Xa activity between patients without vs. with venous thromboembolic events.

Results

19 patients (1.4%) developed a total of 22 venous thromboembolic events. We did not observe a difference of median (IQR) anti-factor Xa activity between patients without venous thromboembolism [peak 0.22 IU/mL (0.14–0.32); 12-h trough 0.1 IU/mL (<0.1–0.17), 24-h trough < 0.1 IU/mL (<0.1– <0.1)] vs. patients with venous thromboembolism [peak 0.33 IU/mL (0.14–0.34); 12-h trough 0.12 IU/mL (<0.1–0.26); 24-h trough < 0.1 IU/mL (<0.1–<0.1)].

Conclusion

Patients who developed venous thromboembolism had anti-factor Xa activities comparable to those who did not suffer from venous thromboembolism.

Pragmatic study of a thromboprophylaxis algorithm in critically ill patients with SARS-COV-2 infection

The optimal thromboprophylactic strategy for patients affected by Coronavirus disease 2019 (COVID-19) has been debated among experts. This study evaluated the safety and efficacy of a thromboprophylaxis algorithm. This was a retrospective, single-center study in critically ill patients admitted to the intensive care unit (University affiliated Hospital) for acute respiratory failure due to Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2). From March 16 to April 9, 2020, thromboprophylaxis was adjusted according to weight (control group, n = 19) and after this date, thromboprophylaxis depended on an algorithm based on thrombotic and hemorrhagic risk factors (protocol group, n = 13). With regard to safety (number of major bleeding events and blood transfusions), the groups were not significantly different. With regard to efficacy, the number of thrombotic events decreased from 37 to 0%, p = 0.025 after implementation of the algorithm. Also, peak fibrinogen dropped from 8.6 (7.2-9.3) to 6.5 (4.6-8.4) g/L, p = 0.041 and D-dimers from 2194 (1464-3763) to 1486 (900-2582) ng/mL, p = 0.0001. In addition, length of stay declined from 19 (10-31) to 5 (3-19) days, p = 0.009. In conclusion, a tailored thromboprophylaxis algorithm (risk stratification based on clinical parameters and biological markers) reduce thrombotic phenomena in critically ill COVID-19 patients without increasing major bleeding.

Clot Stiffness Measured By Seer Sonorheometry As a Marker Of Poor Prognosis In Hospitalized COVID-19 Patients

A high risk of thrombotic complications has been observed among severely ill COVID-19 patients. Viscoelastic tests (VET) have shown a hypercoagulable profile in these patients, although so far there is no clear evidence on the use of these tools as predictors of risk in the clinical course of patients. In this study we aimed to evaluate the association between Quantra® sonorheometry VET parameters, standard coagulation tests and inflammatory markers in 69 patients with COVID-19 on hospital admission with disease severity and outcome. Inflammatory markers were elevated in a high percentage of patients, as were coagulation-related parameters such as fibrinogen and D-dimer levels. Quantra® sonorheometry analysis revealed increased clot stiffness (CS), especially due to increased fibrinogen contribution (FCS) in 63.7%. Analysis of clot stability to lysis (CSL) on the Quantra showed a value of 100%, suggesting hypofibrinolysis, in 32.4%. Age > 65 years, elevated values of fibrinogen, D-dimer, LDH, increased CS and CSL were significantly associated with worsening disease. The combination of elevated FCS and D-dimer values showed a particularly high prognostic value in distinguishing patients with severe symptomatology. In conclusion, FCS measured by Quantra® system and its combination with D-dimer could be established as a powerful tool to identify poor prognosis in COVID-19 patients on hospital admission.

Prevalence and Trajectory of COVID-19-Associated Hypercoagulability Using Serial Thromboelastography in a South African Population

Introduction

The coagulation abnormalities resulting from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been attributed to inflammation and subsequent cytokine storm. Thromboelastography (TEG) is a point-of-care test used to assess clot formation and degradation in whole blood and is an indicator of the overall real-time coagulopathic state of the patient.

Methods

A single-centre, prospective, observational cohort study was conducted in South Africa, analysing the coagulation patterns of 41 patients with hypoxia related to SARS-CoV-2 using serial thromboelastography (TEG) on admission, after 48 hours, and at resolution of hypoxia/day 10. Results: Two-thirds (n = 26) were women. The median age was 61 (IQR 50–67), and the majority (88%) were Black patients. Almost half (22) of the patients were critically ill and ventilated, with median SOFA and SAPS2 scores of 3 and 22 (IQR2-4 and 18–30), respectively. The prevalence of hypercoagulability was 0.54 (95% CI 0.46–0.62), whilst 29/41 (0.71, CI 0.64–0.78)) met the definition of hypofibrinolysis. Differences between the hypercoagulable (HC) and non-hypercoagulable groups remained apparent at 48 hours after anticoagulation. At this time point, the K time was significantly lower (p ˂ 0,01), and the α-angle (p ˂ 0,01) and maximum amplitude (MA) (p ˂ 0,01) were significantly higher in the HC cohort. At resolution of hypoxia, or day 10, only MA was significantly higher in the hypercoagulable group compared to the non-hypercoagulable group (p = 0.01). The initial impairment in fibrinolysis (Ly30), α angle, and MA were significantly associated with mortality, with p values of 0.006, 0.031, and 0.04, respectively.

Conclusions

In this South African population, hypercoagulability was a highly prevalent phenomenon in COVID-19 disease. It was typified by hypofibrinolysis and a persistently elevated MA, despite anticoagulation therapy.

Adequate Antithrombin III Level Predicts Survival in Severe COVID-19 Pneumonia

Critically ill patients with COVID-19 are at an increased thrombotic risk, hence thromboprophylaxis with heparin is considered mandatory. Antithrombin III (ATIII) is the most potent endogenous anticoagulant and is required for the clinical efficacy of heparin. Profound hypercoagulable and inflammatory state associated with COVID-19 can result in decreased ATIII levels and ineffective heparin treatment resulting in increased mortality. The present study evaluated ATIII levels in critically ill patients of COVID-19 and correlated them with other coagulation parameters and disease outcomes. A retrospective review of those critically ill COVID-19 patients was performed who were on a therapeutic dose of low molecular weight heparin (LMWH) and had serial measurements of ATIII, anti-factor Xa (antiFXa) assay and other routine coagulation parameters. A total of 27 critically ill COVID-19 patients were identified, out of these, 12 survived and 15 had disease-induced mortality. ATIII levels were found to be significantly lower in non-survivors on the third day of serial measurement along with worsening of other coagulation parameters. AntiFXa levels were found to be higher in non-survivors as compared to survivors. Further studies are required to establish ATIII as a prognostic marker and to determine the utility of monitoring antiFXa levels in COVID-19 patients on LMWH therapy.

Assessment of anti-factor Xa activity in critically ill COVID-19 patients receiving three different anticoagulation regimens

Introduction:

Critically ill COVID-19 patients are at increased risk of thrombosis with an enhanced risk of bleeding. We aimed to explore the role of anti-factor Xa levels in optimizing the high-intensity anticoagulation’s safety and efficacy and finding possible associations between D-dimer levels, cytokine storm markers, and COVID-19-induced coagulopathy or thrombophilia.

Methods:

Retrospective cohort study conducted on 69 critically ill COVID-19 patients who received three regimens of higher intensity anticoagulation.

Results:

Seventeen patients (24.6%) received high-dose enoxaparin prophylaxis, 29 patients (42%) received therapeutic doses of enoxaparin, and 23 patients (33.3%) were on therapeutic unfractionated heparin infusion. Fewer than one-third of the whole cohort (n = 22; 31.8%) achieved the target range of anti-factor Xa. The patients were divided into three subgroups based on anti-factor Xa target status within each anticoagulation regimen; when compared, the only association observed among them was for interleukin-6 levels, which were significantly higher in both the “above the expected range” and “below the expected range” groups compared with the “within the expected range” group (p = 0.009). Major bleeding episodes occurred in 14 (20.3%) patients and were non-significantly more frequent in the “below the expected anti-factor Xa range group” (p = 0.415). Seven patients (10.1%) developed thrombosis. The majority of patients had anti-factor Xa levels below the expected ranges (four patients, 57.1%).

Conclusion:

Conventional anti-factor Xa ranges may not be appropriate as a predictive surrogate for bleeding in critically ill COVID-19. The clinical decision to initiate therapeutic anticoagulation preemptively may be individualized according to thrombosis and bleeding risks. Cytokine storm markers, namely, interleukin-6, may play a role in COVID-19-induced coagulopathy or thrombophilia.

The Value of Thromboelastography (TEG) in COVID-19 Critical Illness as Illustrated by a Case Series

Objective

To develop a practical thromboelastograph guided (TEG) anticoagulation protocol to guide the management of COVID-19 critically ill patients.

Design

An inter disciplinary team reviewed the current literature on hypercoagulability in critically ill COVID-19 patients, clinical management practices and challenges with high rates of thrombotic events despite anticoagulant therapies.

Setting

The largest tertiary care hospital within the Northwell Health System in New York.

Patients

COVID-19 invasively mechanically ventilated patients in Medical Intensive Care Unit Settings.

Methods

TEG was monitored in critically ill COVID-19 patients. Patterns were reviewed to guide the development of a treatment protocol leveraging TEG parameters to select anticoagulant therapy. Three patients are reported to highlight TEG profiles that led to the development of the algorithm. Clinical trajectory and treatment decisions were extracted retrospectively from the Electronic Health Record, with input from the intensivists. Anticoagulant use, laboratory and TEG values, and venous/arterial lower extremity (LE) ultrasound results were recorded.

Main Results

These patients demonstrated hypercoagulable TEG results despite prophylactic or therapeutic dosages of unfractionated heparin or low-molecular-weight heparin (LMHW). TEG surveillance identified functional fibrinogen and maximum amplitude in high-risk patients with hyper inflammatory markers. Anticoagulation assessment, TEG parameters, and LE ultrasound monitoring for venous and arterial thrombus were used to construct an algorithm to guide and escalate anticoagulant therapy.

Conclusions

TEG provides patient-specific evidence for a hypercoagulable state in patients receiving all types of anticoagulant therapy. The proposed TEG algorithm guides anticoagulation management decisions to maintain or escalate anticoagulant dose and/or change choice of anticoagulant. A TEG algorithm may help negotiate the potential harm/benefit balance of full-dose anticoagulation in critically ill COVID-19 patients, by allowing for a more individualized approach that goes beyond the review of activated partial thromboplastin time (aPTT) levels.

Heparin - Messias or Verschlimmbesserung?

A heightened risk of thrombosis noted early on with the severe acute respiratory syndrome coronavirus 2 infection led to the widespread use of heparin anticoagulation in the coronavirus disease 2019 (COVID-19) pandemic. However, reports soon started appearing in the literature where an apparent failure of heparin to prevent thrombotic events was observed in hospitalized patients with this viral infection. In this review, we explore the likely mechanisms for heparin failure with particular relevance to COVID-19. We also explore the role of anti-Xa assays and global hemostatic tests in this context. The current controversy of dosing heparin in this disease is detailed with some possible mechanistic reasons for anticoagulant failure. We hope that lessons learnt from the use of heparin in COVID-19 could assist us in the appropriate use of this anticoagulant in the future.

Preventing Thrombohemorrhagic Complications of Heparinized COVID-19 Patients Using Adjunctive Thromboelastography: A Retrospective Study

BACKGROUND

The treatment of COVID-19 patients with heparin is not always effective in preventing thrombotic complications, but can also be associated with bleeding complications, suggesting a balanced approach to anticoagulation is needed. A prior pilot study supported that thromboelastography and conventional coagulation tests could predict hemorrhage in COVID-19 in patients treated with unfractionated heparin or enoxaparin, but did not evaluate the risk of thrombosis.

METHODS

This single-center, retrospective study included 79 severely ill COVID-19 patients anticoagulated with intermediate or therapeutic dose unfractionated heparin. Two stepwise logistic regression models were performed with bleeding or thrombosis as the dependent variable, and thromboelastography parameters and conventional coagulation tests as the independent variables.

RESULTS

Among all 79 patients, 12 (15.2%) had bleeding events, and 20 (25.3%) had thrombosis. Multivariate logistic regression analysis identified a prediction model for bleeding (adjusted R² = 0.787, p < 0.001) comprised of increased reaction time (p = 0.016), decreased fibrinogen (p = 0.006), decreased D-dimer (p = 0.063), and increased activated partial thromboplastin time (p = 0.084). Multivariate analysis of thrombosis identified a weak prediction model (adjusted R² = 0.348, p < 0.001) comprised of increased D-dimer (p < 0.001), decreased reaction time (p = 0.002), increased maximum amplitude (p < 0.001), and decreased alpha angle (p = 0.014). Adjunctive thromboelastography decreased the use of packed red cells (p = 0.031) and fresh frozen plasma (p < 0.001).

CONCLUSIONS

Significantly, this study demonstrates the need for a precision-based titration strategy of anticoagulation for hospitalized COVID-19 patients. Since severely ill COVID-19 patients may switch between thrombotic or hemorrhagic phenotypes or express both simultaneously, institutions may reduce these complications by developing their own titration strategy using daily conventional coagulation tests with adjunctive thromboelastography.

Viscoelastometric Testing to Assess Hemostasis of COVID-19: A Systematic Review

Infection by SARS-CoV-2 is associated with a high risk of thrombosis. The laboratory documentation of hypercoagulability and impaired fibrinolysis remains a challenge. Our aim was to assess the potential usefulness of viscoelastometric testing (VET) to predict thrombotic events in COVID-19 patients according to the literature. We also (i) analyzed the impact of anticoagulation and the methods used to neutralize heparin, (ii) analyzed whether maximal clot mechanical strength brings more information than Clauss fibrinogen, and (iii) critically scrutinized the diagnosis of hypofibrinolysis. We performed a systematic search in PubMed and Scopus databases until 31st December 2020. VET methods and parameters, and patients' features and outcomes were extracted. VET was performed for 1063 patients (893 intensive care unit (ICU) and 170 non-ICU, 44 studies). There was extensive heterogeneity concerning study design, VET device used (ROTEM, TEG, Quantra and ClotPro) and reagents (with non-systematic use of heparin neutralization), timing of assay, and definition of hypercoagulable state. Notably, only 4 out of 25 studies using ROTEM reported data with heparinase (HEPTEM). The common findings were increased clot mechanical strength mainly due to excessive fibrinogen component and impaired to absent fibrinolysis, more conspicuous in the presence of an added plasminogen activator. Only 4 studies out of the 16 that addressed the point found an association of VETs with thrombotic events. So-called functional fibrinogen assessed by VETs showed a variable correlation with Clauss fibrinogen. Abnormal VET pattern, often evidenced despite standard prophylactic anticoagulation, tended to normalize after increased dosing. VET studies reported heterogeneity, and small sample sizes do not support an association between the poorly defined prothrombotic phenotype of COVID-19 and thrombotic events.

The Role of TEG Analysis in Patients with COVID-19-Associated Coagulopathy: A Systematic Review

Coronavirus disease 2019 (COVID-19)-associated coagulopathy (CAC), characterized by hypercoagulability and an increased risk of thrombotic complications, is an important consideration in the management of patients with COVID-19. As COVID-19 is a new disease, no standard of care for the diagnosis or management of its associated coagulopathy is yet established. Whole blood viscoelastic tests, such as thromboelastography (TEG^® hemostasis analyzer), analyze whole blood to provide a complete overview of the coagulation status. We conducted a systematic review of thromboelastography for management of patients with COVID-19, using MEDLINE (PubMed) and Cochrane databases. TEG^® parameter measurements and clinical outcomes data were extracted for analysis. Our review found 15 publications, with overall results showing thromboelastography can identify and assess a hypercoagulable state in patients with COVID-19. Furthermore, utilization of thromboelastography in this patient population was shown to predict thrombotic complications. The benefits of thromboelastography presented here, in addition to advantages compared with laboratory coagulation tests, position thromboelastography as an important opportunity for optimizing diagnosis of CAC and improving patient management in COVID-19. Given that the benefits of thromboelastography have already been demonstrated in several other clinical applications, we anticipate that clinical data from future studies in patients with COVID-19 will further elucidate the optimal use of thromboelastography in this patient population.

Assessment of anti-factor Xa activity in critically ill COVID-19 patients receiving three different anticoagulation regimens

Introduction:

Critically ill COVID-19 patients are at increased risk of thrombosis with an enhanced risk of bleeding. We aimed to explore the role of anti-factor Xa levels in optimizing the high-intensity anticoagulation’s safety and efficacy and finding possible associations between D-dimer levels, cytokine storm markers, and COVID-19-induced coagulopathy or thrombophilia.

Methods:

Retrospective cohort study conducted on 69 critically ill COVID-19 patients who received three regimens of higher intensity anticoagulation.

Results:

Seventeen patients (24.6%) received high-dose enoxaparin prophylaxis, 29 patients (42%) received therapeutic doses of enoxaparin, and 23 patients (33.3%) were on therapeutic unfractionated heparin infusion. Fewer than one-third of the whole cohort ( n = 22; 31.8%) achieved the target range of anti-factor Xa. The patients were divided into three subgroups based on anti-factor Xa target status within each anticoagulation regimen; when compared, the only association observed among them was for interleukin-6 levels, which were significantly higher in both the “above the expected range” and “below the expected range” groups compared with the “within the expected range” group ( p = 0.009). Major bleeding episodes occurred in 14 (20.3%) patients and were non-significantly more frequent in the “below the expected anti-factor Xa range group” ( p = 0.415). Seven patients (10.1%) developed thrombosis. The majority of patients had anti-factor Xa levels below the expected ranges (four patients, 57.1%).

Conclusion:

Conventional anti-factor Xa ranges may not be appropriate as a predictive surrogate for bleeding in critically ill COVID-19. The clinical decision to initiate therapeutic anticoagulation preemptively may be individualized according to thrombosis and bleeding risks. Cytokine storm markers, namely, interleukin-6, may play a role in COVID-19-induced coagulopathy or thrombophilia.

Coronavirus Disease 2019-Associated Thrombosis and Coagulopathy: Review of the Pathophysiological Characteristics and Implications for Antithrombotic Management

Coronavirus disease 2019 (COVID‐19) is an infectious disease caused by severe acute respiratory syndrome coronavirus‐2, which has posed a significant threat to global health. Although the infection is frequently asymptomatic or associated with mild symptoms, in a small proportion of patients it can produce an intense inflammatory and prothrombotic state that can lead to acute respiratory distress syndrome, multiple organ failure, and death. Angiotensin‐converting enzyme 2, highly expressed in the respiratory system, has been identified as a functional receptor for severe acute respiratory syndrome coronavirus‐2. Notably, angiotensin‐converting enzyme 2 is also expressed in the cardiovascular system, and there are multiple cardiovascular implications of COVID‐19. Cardiovascular risk factors and cardiovascular disease have been associated with severe manifestations and poor prognosis in patients with COVID‐19. More important, patients with COVID‐19 may have thrombotic and coagulation abnormalities, promoting a hypercoagulable state and resulting in an increased rate of thrombotic and thromboembolic events. This review will describe the pathophysiological characteristics of the cardiovascular involvement following infection by severe acute respiratory syndrome coronavirus‐2, with a focus on thrombotic and thromboembolic manifestations and implications for antithrombotic management.