How to recognize and manage COVID-19-associated coagulopathy

Unraveling the enigma of long COVID: novel aspects in pathogenesis, diagnosis, and treatment protocols

Long COVID, now unmistakably identified as a syndromic entity encompassing a complex spectrum of symptoms, demands immediate resolution of its elusive pathogenic underpinnings. The intricate interplay of diverse factors presents a complex puzzle, difficult to resolve, and thus poses a substantial challenge. As instances of long COVID manifest by repeated infections of SARS-CoV-2 and genetic predisposition, a detailed understanding in this regard is needed. This endeavor is a comprehensive exploration and analysis of the cascading pathogenetic events driven by viral persistence and replication. Beyond its morbidity, long COVID, more disabling than fatal, exacts one of the most substantial tolls on public health in contemporary times, with the potential to cripple national economies. The paper introduces a unified theory of long COVID, detailing a novel pathophysiological framework that interlinks persistent SARS-CoV-2 infection, autoimmunity, and systemic vascular pathology. We posit a model where viral reservoirs, immune dysregulation, and genetic predispositions converge to perpetuate disease. It challenges prevailing hypotheses with new evidence, suggesting innovative diagnostic and therapeutic approaches. The paper aims to shift the paradigm in long COVID research by providing an integrative perspective that encapsulates the multifaceted nature of the condition. We explain the immunological mechanisms, hypercoagulability states, and viral reservoirs in the skull that feed NeuroCOVID in patients with long COVID. Also, this study hints toward a patient approach and how to prioritize treatment sequences in long COVID patients in hospitals and clinics.

Thromboinflammation in COVID-19: Unraveling the interplay of coagulation and inflammation

The coronavirus disease 2019 (COVID-19) pandemic has not only challenged global health systems but also spurred intense scientific inquiry into its pathophysiology. Among the multifaceted aspects of the disease, coagulation abnormalities have emerged as a significant contributor to morbidity and mortality. From endothelial dysfunction to dysregulated immune responses, various factors contribute to the hypercoagulable state seen in severe COVID-19 cases. The dysregulation of coagulation in COVID-19 extends beyond traditional thromboembolic events, encompassing a spectrum of abnormalities ranging from microvascular thrombosis to disseminated intravascular coagulation (DIC). Endothelial injury induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection triggers a cascade of events involving platelet activation, coagulation factor consumption, and fibrinolysis impairment. Moreover, the virus direct effects on immune cells and the cytokine storm further exacerbate the prothrombotic milieu. Unraveling this intricate web of interactions between viral pathogenesis and host responses is essential for elucidating novel therapeutic targets and refining existing management strategies for COVID-19-associated coagulopathy. In the quest to unravel the complex interplay between coagulation and COVID-19, numerous clinical and laboratory studies have yielded invaluable insights into potential biomarkers, prognostic indicators, and therapeutic avenues. Anticoagulation therapy has emerged as a cornerstone in the management of severe COVID-19, although optimal dosing regimens and patient selection criteria remain subjects of ongoing investigation. Additionally, innovative approaches such as targeting specific components of the coagulation cascade or modulating endothelial function hold promise for future therapeutic development.

Four years into the pandemic, managing COVID-19 patients with acute coagulopathy: what have we learned?

Coagulopathy alongside micro- and macrovascular thrombotic events were frequent characteristics of patients presenting with acute COVID-19 during the initial stages of the pandemic. However, over the past 4 years, the incidence and manifestations of COVID-19-associated coagulopathy have changed due to immunity from natural infection and vaccination and the appearance of new SARS-CoV-2 variants. Diagnostic criteria and management strategies based on early experience and studies for COVID-19-associated coagulopathy thus require reevaluation. As many other infectious disease states are also associated with hemostatic dysfunction, the coagulopathy associated with COVID-19 may be compounded, especially throughout the winter months, in patients with diverse etiologies of COVID-19 and other infections. This commentary examines what we have learned about COVID-19-associated coagulopathy throughout the pandemic and how we might best prepare to mitigate the hemostatic consequences of emerging infection agents.

It's in the blood: a review of the hematological system in SARS-CoV-2-associated COVID-19

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to an unprecedented global healthcare crisis. While SARS-CoV-2-associated COVID-19 affects primarily the respiratory system, patients with COVID-19 frequently develop extrapulmonary manifestations. Notably, changes in the hematological system, including lymphocytopenia, neutrophilia and significant abnormalities of hemostatic markers, were observed early in the pandemic. Hematological manifestations have since been recognized as important parameters in the pathophysiology of SARS-CoV-2 and in the management of patients with COVID-19. In this narrative review, we summarize the state-of-the-art regarding the hematological and hemostatic abnormalities observed in patients with SARS-CoV-2-associated COVID-19, as well as the current understanding of the hematological system in the pathophysiology of acute and chronic SARS-CoV-2-associated COVID-19.

An Evolving Understanding of the Basis and Management of Vascular Complications of COVID-19: Where Do We Go From Here?

The COVID-19 pandemic led to millions of deaths worldwide after its emergence in 2020. The SARS-CoV-2 virus primarily affects respiratory function, but immune dysregulation leading to systemic inflammation, endothelial dysfunction, and coagulopathy can predispose to systemic complications including hematologic and vascular complications. Treatment strategies for patients with COVID-19 have rapidly evolved and the effectiveness and safety of antithrombotic agents have been evaluated in multiple clinical trials. The findings have spurred interest in the prevention and treatment of the hematologic and vascular complications of non-COVID-19 respiratory infections. This review is focused on hematological and vascular complications of COVID-19, including their pathophysiology, clinical manifestations, and management. Because of the perpetually changing nature of the disease, the review places previous data in temporal contexts and outlines potential next steps for future research in COVID-19 and other severe respiratory infections.

Platelet Activation and Thrombosis in COVID-19

Although thrombosis frequently occurs in infectious diseases, the coagulopathy associated with COVID-19 has unique characteristics. Compared with bacterial sepsis, COVID-19-associated coagulopathy presents with minimal changes in platelet counts, normal prothrombin times, and increased D-dimer and fibrinogen levels. These differences can be explained by the distinct pathophysiology of the thromboinflammatory responses. In sepsis-induced coagulopathy, leukocytes are primarily responsible for the coagulopathy by expressing tissue factor, releasing neutrophil extracellular traps, multiple procoagulant substances, and systemic endothelial injury that is often associated with vasoplegia and shock. In COVID-19-associated coagulopathy, platelet activation is a major driver of inflammation/thrombogenesis and von Willebrand factor and platelet factor 4 are deeply involved in the pathogenesis. Although the initial responses are localized to the lung, they can spread systemically if the disease is severe. Since the platelets play major roles, arterial thrombosis is not uncommon in COVID-19. Despite platelet activation, platelet count is usually normal at presentation, but sensitive biomarkers including von Willebrand factor activity, soluble P-selectin, and soluble C-type lectin-like receptor-2 are elevated, and they increase as the disease progresses. Although the role of antiplatelet therapy is still unproven, current studies are ongoing to determine its potential effects.

Reply to Bareille et al. Are Viscoelastometric Assays of Old Generation Ready for Disposal? Comment on "Volod et al. Viscoelastic Hemostatic Assays: A Primer on Legacy and New Generation Devices. J. Clin. Med. 2022, 11, 860"

We are pleased to see that Bareille et al. have written a Commentary: "Are viscoelastometric assays of old generation ready for disposal?" [...].

Practical Recommendations for Optimal Thromboprophylaxis in Patients with COVID-19: A Consensus Statement Based on Available Clinical Trials

Coronavirus disease 2019 (COVID-19) has been shown to be strongly associated with increased risk for venous thromboembolism events (VTE) mainly in the inpatient but also in the outpatient setting. Pharmacologic thromboprophylaxis has been shown to offer significant benefits in terms of reducing not only VTE events but also mortality, especially in acutely ill patients with COVID-19. Although the main source of evidence is derived from observational studies with several limitations, thromboprophylaxis is currently recommended for all hospitalized patients with acceptable bleeding risk by all national and international guidelines. Recently, high quality data from randomized controlled trials (RCTs) further support the role of thromboprophylaxis and provide insights into the optimal thromboprophylaxis strategy. The aim of this statement is to systematically review all the available evidence derived from RCTs regarding thromboprophylaxis strategies in patients with COVID-19 in different settings (either inpatient or outpatient) and provide evidence-based guidance to practical questions in everyday clinical practice. Clinical questions accompanied by practical recommendations are provided based on data derived from 20 RCTs that were identified and included in the present study. Overall, the main conclusions are: (i) thromboprophylaxis should be administered in all hospitalized patients with COVID-19, (ii) an optimal dose of inpatient thromboprophylaxis is dependent upon the severity of COVID-19, (iii) thromboprophylaxis should be administered on an individualized basis in post-discharge patients with COVID-19 with high thrombotic risk, and (iv) thromboprophylaxis should not be routinely administered in outpatients. Changes regarding the dominant SARS-CoV-2 variants, the wide immunization status (increasing rates of vaccination and reinfections), and the availability of antiviral therapies and monoclonal antibodies might affect the characteristics of patients with COVID-19; thus, future studies will inform us about the thrombotic risk and the optimal therapeutic strategies for these patients.

SARS-CoV-2 and COVID-19: A Narrative Review

The World Health Organisation has reported that the viral disease known as COVID-19, caused by SARS-CoV-2, is the leading cause of death by a single infectious agent. This narrative review examines certain components of the pandemic: its origins, early clinical data, global and UK-focussed epidemiology, vaccination, variants, and long COVID.

COVID-19 and antiphospholipid antibodies

Antiphospholipid syndrome and the coagulopathy of COVID-19 share many pathophysiologic features, including endotheliopathy, hypercoagulability, and activation of platelets, complement pathways, and neutrophil extracellular traps, all acting in concert via a model of immunothrombosis. Antiphospholipid antibody production in COVID-19 is common, with 50% of COVID-19 patients being positive for lupus anticoagulant in some studies, and with non-Sapporo criteria antiphospholipid antibodies being prevalent as well. The biological significance of antiphospholipid antibodies in COVID-19 is uncertain, as such antibodies are usually transient, and studies examining clinical outcomes in COVID-19 patients with and without antiphospholipid antibodies have yielded conflicting results. In this review, we explore the biology of antiphospholipid antibodies in COVID-19 and other infections and discuss mechanisms of thrombogenesis in antiphospholipid syndrome and parallels with COVID-19 coagulopathy. In addition, we review the existing literature on safety of COVID-19 vaccination in patients with antiphospholipid antibodies and antiphospholipid syndrome.

Thrombotic events in critically ill children with coronavirus disease 2019 or multisystem inflammatory syndrome in children

PURPOSE OF REVIEW

To provide an update regarding what is known about thrombotic events and thromboprophylaxis in critically ill children with SARS-CoV-2 infection.

RECENT FINDINGS

Pediatric patients with SARS-CoV-2 generally have mild illness; however, intensive care is required in about 20-30% of hospitalized children with COVID-19 and an even higher proportion in those with MIS-C. Increased rates of thrombosis have been observed in adults hospitalized with COVID-19, and clinical trials have attempted to optimize thromboprophylaxis. There is significant variability in the estimated incidence of thrombosis in pediatric patients (0-27%) because of variation in patient populations and study design. Multiple studies demonstrate an increased rate of thrombosis compared with baseline in hospitalized pediatric patients. Few studies have evaluated risk factors for thrombosis, but critical illness, older age, and other known thrombosis risk factors appear to increase the risk. Thromboprophylaxis strategies are inconsistent, with little evidence of efficacy but few reports of major bleeding.

SUMMARY

Critically ill children with SARS-CoV-2-related illnesses are at increased risk of thrombosis. Thromboprophylaxis should be considered in select patients with COVID-19 or MIS-C, though the optimal strategy is not yet known. More data is required to guide practice to prevent thrombosis in this population.

COVID-19 in dialysis: clinical impact, immune response, prevention, and treatment

The COVID-19 pandemic has profound adverse effects on the population on dialysis. Patients requiring dialysis are at an increased risk of SARS-CoV-2 infection and mortality, and many have experienced psychological distress as well as delayed or suboptimal care. COVID-19 survivors have prolonged viral shedding, but generally develop a robust and long-lasting humoral immune response that correlates with initial disease severity. However, protection against reinfection is incomplete. A growing body of evidence reveals delayed and blunted immune responses to SARS-CoV-2 vaccination. Administration of a third dose within 1 to 2 months of prime-boost vaccination significantly increases antibody levels, in particular in patients with poor initial responses. Patients on dialysis have inferior immune responses to adenoviral vector vaccines than to mRNA vaccines. The immunogenicity of the mRNA-1273 vaccine is markedly better than that of the BNT162b2 vaccine, most likely by virtue of its higher mRNA content. Despite suboptimal immune responses in patients on dialysis, preliminary data suggest that vaccination partially protects against infection and severe disease requiring hospitalization. However, progressive waning of immunity and emergence of SARS-CoV-2 variants with a high potential of immune escape call for a booster dose in all patients on dialysis 4 to 6 months after prime-boost vaccination. Patients with persistent poor vaccine responses may be candidates for primary prophylaxis strategies. In the absence of specific data in patients on dialysis, therapeutic strategies in the event of established COVID-19 must be extrapolated from evidence obtained in the population not on dialysis. Neutralizing monoclonal antibodies may be an attractive option after a high-risk exposure or during the early course of infection.

A central role for amyloid fibrin microclots in long COVID/PASC: origins and therapeutic implications

Post-acute sequelae of COVID (PASC), usually referred to as 'Long COVID' (a phenotype of COVID-19), is a relatively frequent consequence of SARS-CoV-2 infection, in which symptoms such as breathlessness, fatigue, 'brain fog', tissue damage, inflammation, and coagulopathies (dysfunctions of the blood coagulation system) persist long after the initial infection. It bears similarities to other post-viral syndromes, and to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Many regulatory health bodies still do not recognize this syndrome as a separate disease entity, and refer to it under the broad terminology of 'COVID', although its demographics are quite different from those of acute COVID-19. A few years ago, we discovered that fibrinogen in blood can clot into an anomalous 'amyloid' form of fibrin that (like other β-rich amyloids and prions) is relatively resistant to proteolysis (fibrinolysis). The result, as is strongly manifested in platelet-poor plasma (PPP) of individuals with Long COVID, is extensive fibrin amyloid microclots that can persist, can entrap other proteins, and that may lead to the production of various autoantibodies. These microclots are more-or-less easily measured in PPP with the stain thioflavin T and a simple fluorescence microscope. Although the symptoms of Long COVID are multifarious, we here argue that the ability of these fibrin amyloid microclots (fibrinaloids) to block up capillaries, and thus to limit the passage of red blood cells and hence O2 exchange, can actually underpin the majority of these symptoms. Consistent with this, in a preliminary report, it has been shown that suitable and closely monitored 'triple' anticoagulant therapy that leads to the removal of the microclots also removes the other symptoms. Fibrin amyloid microclots represent a novel and potentially important target for both the understanding and treatment of Long COVID and related disorders.