COVID-19 and Its Implications for Thrombosis and Anticoagulation.

Venous thromboembolism, occlusion of dialysis catheters, circuit thrombosis in extracorporeal membrane oxygenation (ECMO) devices, acute limb ischemia, and isolated strokes, all in the face of prophylactic and even therapeutic anticoagulation, are features of novel coronavirus disease 2019 (COVID-19) coagulopathy. It seems well established at this time that a COVID-19 patient deemed sick enough to be hospitalized, should receive at least prophylactic dose anticoagulation. However, should some hospitalized patients have dosage escalation to intermediate dose? Should some be considered for full-dose anticoagulation without a measurable thromboembolic event and how should that anticoagulation be monitored? Should patients receive postdischarge anticoagulation and with what medication and for how long? What thrombotic issues are related to the various medications being used to treat this coagulopathy? Is antiphospholipid antibody part of this syndrome? What is the significance of isolated ischemic stroke and limb ischemia in this disorder and how does this interface with the rest of the clinical and laboratory features of this disorder? The aims of this article are to explore these questions and interpret the available data based on the current evidence.

COVID-19 Severity Potentially Modulated by Cardiovascular-Disease-Associated Immune Dysregulation.

Patients with underlying cardiovascular conditions are particularly vulnerable to severe COVID-19. In this project, we aimed to characterize similarities in dysregulated immune pathways between COVID-19 patients and patients with cardiomyopathy, venous thromboembolism (VTE), or coronary artery disease (CAD). We hypothesized that these similarly dysregulated pathways may be critical to how cardiovascular diseases (CVDs) exacerbate COVID-19. To evaluate immune dysregulation in different diseases, we used four separate datasets, including RNA-sequencing data from human left ventricular cardiac muscle samples of patients with dilated or ischemic cardiomyopathy and healthy controls; RNA-sequencing data of whole blood samples from patients with single or recurrent event VTE and healthy controls; RNA-sequencing data of human peripheral blood mononuclear cells (PBMCs) from patients with and without obstructive CAD; and RNA-sequencing data of platelets from COVID-19 subjects and healthy controls. We found similar immune dysregulation profiles between patients with CVDs and COVID-19 patients. Interestingly, cardiomyopathy patients display the most similar immune landscape to COVID-19 patients. Additionally, COVID-19 patients experience greater upregulation of cytokine- and inflammasome-related genes than patients with CVDs. In all, patients with CVDs have a significant overlap of cytokine- and inflammasome-related gene expression profiles with that of COVID-19 patients, possibly explaining their greater vulnerability to severe COVID-19.

Heparins and 2019-nCoV infection: a narrative review.

OBJECTIVE: Patients with 2019-nCoV infection have a high risk to develop venous thrombotic events. Several guidelines recommend the use of either unfractionated heparin or low molecular weight heparins in preventing thrombotic events in these patients. However, results from clinical studies, so far published, reached controversial conclusions on heparin efficacy in this kind of patients since the incidence of venous thromboembolism remains high despite prophylaxis. This narrative review aims to provide an overview of the antiviral and anti-inflammatory properties of heparins and their efficacy and safety in SARS-CoV-2 medical ward-patients. Moreover, anatomical findings and ongoing trials are also reported. Finally, this narrative review tries to explain why heparins fail to prevent venous thrombosis. MATERIALS AND METHODS: We searched for the most relevant published studies on heparins and 2019-nCoV infected patients using the MEDLINE electronic database in the period between January and December 2020. Articles were preliminarily defined as eligible if they: a) were in English language, b) enrolled 250 or more medical ward-patients and 100 or more ICU-patients, c) reported results on patients treated with heparins in a percentage of at least 70% and d) performed an objectively confirmed diagnosis of VTE. RESULTS: Data from medium to large scientific studies show that the incidence of venous thrombotic events in medical ward-patients with SARS-CoV-2 vary between 0% and 8.3%, while this rate is higher, from 6.2% to 49%, in Intensive Care Unit-patients. However, heparins reduce the mortality rate in these patients of about 50%. Histological findings show that thrombosis could affect capillaries, main and small-mid-sized vessels, and it is associated with diffuse alveolar damage. CONCLUSIONS: Heparins have anti-inflammatory and anti-viral properties, which may be of help in reducing mortality in SARS-CoV-2 patients. Failure of heparins at prophylactic dosages in preventing VTE, especially in ICU-patients, could be due to the severity of the disease. Data on the use of heparins in an early phase of the 2019-nCoV infection are still lacking.

Antiphospholipid antibodies in critically ill COVID-19 patients with thromboembolism: cause of disease or epiphenomenon?

Coronavirus 2019 disease (COVID-19) is associated with coagulation dysfunction that predisposes patients to an increased risk for both arterial (ATE) and venous thromboembolism (VTE) and consequent poor prognosis; in particular, the incidence of ATE and VTE in critically ill COVID-19 patients can reach 5% and 31%, respectively. The mechanism of thrombosis in COVID-19 patients is complex and still not completely clear. Recent literature suggests a link between the presence of antiphospholipid antibodies (aPLs) and thromboembolism in COVID-19 patients. However, it remains uncertain whether aPLs are an epiphenomenon or are involved in the pathogenesis of the disease.

Association of Neutrophil Activation, More Than Platelet Activation, With Thrombotic Complications in Coronavirus Disease 2019.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 infection is associated with hypercoagulability, which predisposes to venous thromboembolism (VTE). We analyzed platelet and neutrophil activation in patients with coronavirus disease 2019 (COVID-19) and their association with VTE. METHODS: Hospitalized patients with COVID-19 and age- and sex-matched healthy controls were studied. Platelet and leukocyte activation, neutrophil extracellular traps (NETs), and matrix metalloproteinase 9, a neutrophil-released enzyme, were measured. Four patients were restudied after recovery. The activating effect of plasma from patients with COVID-19 on control platelets and leukocytes and the inhibiting activity of common antithrombotic agents on it were studied. RESULTS: A total of 36 patients with COVID-19 and 31 healthy controls were studied; VTE developed in 8 of 36 patients with COVID-19 (22.2%). Platelets and neutrophils were activated in patients with COVID-19. NET, but not platelet activation, biomarkers correlated with disease severity and were associated with thrombosis. Plasmatic matrix metalloproteinase 9 was significantly increased in patients with COVID-19. Platelet and neutrophil activation markers, but less so NETs, normalized after recovery. In vitro, plasma from patients with COVID-19 triggered platelet and neutrophil activation and NET formation, the latter blocked by therapeutic-dose low-molecular-weight heparin, but not by aspirin or dypiridamole. CONCLUSIONS: Platelet and neutrophil activation are key features of patients with COVID-19. NET biomarkers may help to predict clinical worsening and VTE and may guide low-molecular-weight heparin treatment.

COVID-19, immunothrombosis and venous thromboembolism: biological mechanisms.

Thrombotic events that frequently occur in COVID-19 are predominantly venous thromboemboli (VTE) and are associated with increasing disease severity and worse clinical outcomes. Distinctive microvascular abnormalities in COVID-19 include endothelial inflammation, disruption of intercellular junctions and microthrombi formation. A distinct COVID-19-associated coagulopathy along with increased cytokines and activation of platelets, endothelium and complement occur in COVID-19, which is more frequent with worsening disease severity. This proinflammatory milieu may result in immunothrombosis, a host defence mechanism that can become dysregulated, leading to excess formation of immunologically mediated thrombi which predominantly affect the microvasculature. The haemostatic and immune systems are intricately linked, and multifactorial processes are likely to contribute to VTE and immunothrombosis in COVID-19. This state-of-the-art review will explore the pathobiological mechanisms of immunothrombosis and VTE in COVID-19 focusing on: COVID-19-associated coagulopathy, pathology, endothelial dysfunction and haemostasis, the immune system and thrombosis, genetic associations and additional thrombotic mechanisms. An understanding of the complex interplay between these processes is necessary for developing and assessing how new treatments affect VTE and immunothrombosis in COVID-19.

Cardiovascular Manifestations and Mechanisms in Patients with COVID-19.

Coronavirus disease 2019 (COVID-19) patients with pre-existing cardiovascular disease (CVD) or with cardiovascular complications have a higher risk of mortality. The main cardiovascular complications of COVID-19 include acute cardiac injury, acute myocardial infarction (AMI), myocarditis, arrhythmia, heart failure, shock, and venous thromboembolism (VTE)/pulmonary embolism (PE). COVID-19 can cause cardiovascular complications or deterioration of coexisting CVD through direct or indirect mechanisms, including viral toxicity, dysregulation of the renin-angiotensin-aldosterone system (RAAS), endothelial cell damage and thromboinflammation, cytokine storm, and oxygen supply-demand mismatch. We systematically review cardiovascular manifestations, histopathology, and mechanisms of COVID-19, to help to formulate future research goals and facilitate the development of therapeutic management strategies.

Immunothrombosis and thromboinflammation in host defense and disease.

Platelets are increasingly being recognized for playing roles beyond thrombosis and hemostasis. Today we know that they mediate inflammation by direct interactions with innate immune cells or secretion of cytokines/chemokines. Here we review their interactions with neutrophils and monocytes/macrophages in infection and sepsis, stroke, myocardial infarction and venous thromboembolism. We discuss new roles for platelet surface receptors like GPVI or GPIb and also look at platelet contributions to the formation of neutrophil extracellular traps (NETs) as well as to deep vein thrombosis during infection, e.g. in COVID-19 patients.

The clinical impact of COVID-19 epidemic in the hematologic setting.

The rapid onset and worldwide spread of the COVID-19 epidemic (caused by SARS-CoV-2 coronavirus) has been associated with a profound impact in clinical practice also in the hematologic setting. First of all, given the immunosuppressive effect of many therapies that are normally administered to patients with hematological diseases, with a consequent increased risk of contracting a more severe viral infection, it has been necessary to reconsider in each individual patient the urgency and priority of the treatments foreseen by the normal standards of care. In particular, as regards allogeneic (and to a lesser extent autologous) hematopoietic cell transplantation and CAR T-cell therapy, specific recommendations have been issued by the transplant community on the criteria to be used to decide whether or not to postpone these procedures and on the clinical management of recipients and donors exposed to COVID-19. As to cytotoxic chemotherapy and other antineoplastic therapies, criteria have been proposed to decide, in the various clinical situations, which treatments were not deferrable and which instead could be postponed or replaced by less aggressive therapies. In the outpatient clinics, various organizational solutions for telemedicine have been adopted, resorting to telephone interviews and/or Information Technology, with the aim of reducing the influx of patients while maintaining an adequate control of their clinical condition. The collection of blood by the transfusion centers has been the subject of organizational measures, in order to avoid the transmission of COVID 19 while maintaining a sufficient blood collection for clinical needs. Finally, some hematologic laboratory alterations have been identified, such as thrombocytopenia, lymphopenia and coagulation abnormalities, useful for the prognostic evaluation of infected patients.