Thrombosis of pulmonary vasculature despite anticoagulation and thrombolysis: The findings from seven autopsies

Quantitative chest CT imaging characteristics and outcome of patients with COVID-19 associated pulmonary artery thrombosis: A single-center retrospective cohort study

Coronavirus disease 2019 (COVID-19)-associated pulmonary thrombotic events occur frequently and are associated with disease severity and worse clinical outcomes. We aimed to describe the clinical and quantitative chest computed tomography (CT) imaging characteristics based on density ranges (Hounsfield units) and the outcomes of patients with COVID-19 associated pulmonary artery thrombosis. This retrospective cohort study included all patients with COVID-19 hospitalized in a tertiary care hospital between March 2020 and June 2022 who underwent a CT pulmonary angiography. We included 73 patients: 36 (49.3%) with and 37 (50.7%) without pulmonary artery thrombosis. The in-hospital all-cause mortality was 22.2 versus 18.9% ( P  = .7), and the intensive care unit admission rates were 30.5 versus 8.1% ( P  = .01) at the time of diagnosis of pulmonary artery thrombosis. Except for D-dimers (median of 3142 vs 533, P  = .002), the other clinical, coagulopathy, and inflammatory markers were similar. Logistic regression analysis revealed that only D-dimers were associated with pulmonary artery thrombosis ( P  = .012). ROC curve analysis of D-dimers showed that a value greater than 1716 ng/mL predicted pulmonary artery thrombosis with an area under the curve of 0.779, 72.2% sensitivity, and 73% specificity (95% CI 0.672-0.885). Peripheral distribution of pulmonary artery thrombosis was recorded in 94.5% of cases. In the lower lobes of the lungs, the incidence of pulmonary artery thrombosis was 6 times higher than that in the upper lobes (58-64%), with a percentage of lung injury of 80% to 90%. Analysis of the distribution of arterial branches with filling defects revealed that 91.6% occurred in lung areas with inflammatory lesions. Quantitative chest CT imaging provides valuable information regarding the extent of COVID-19 associated lung damage and can be used to anticipate the co-location of pulmonary immunothrombotic events. In patients with severe COVID-19, in-hospital all-cause mortality was similar regardless of the presence of associated distal pulmonary thrombosis.

Mechanisms of COVID-19 Associated Pulmonary Thrombosis: A Narrative Review

COVID-19, the infectious disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), is frequently associated with pulmonary thrombotic events, especially in hospitalized patients. Severe SARS-CoV-2 infection is characterized by a proinflammatory state and an associated disbalance in hemostasis. Immune pathology analysis supports the inflammatory nature of pulmonary arterial thrombi composed of white blood cells, especially neutrophils, CD3+ and CD20+ lymphocytes, fibrin, red blood cells, and platelets. Immune cells, cytokines, chemokines, and the complement system are key drivers of immunothrombosis, as they induce the damage of endothelial cells and initiate proinflammatory and procoagulant positive feedback loops. Neutrophil extracellular traps induced by COVID-19-associated "cytokine storm", platelets, red blood cells, and coagulation pathways close the inflammation-endotheliopathy-thrombosis axis, contributing to SARS-CoV-2-associated pulmonary thrombotic events. The hypothesis of immunothrombosis is also supported by the minor role of venous thromboembolism with chest CT imaging data showing peripheral blood clots associated with inflammatory lesions and the high incidence of thrombotic events despite routine thromboprophylaxis. Understanding the complex mechanisms behind COVID-19-induced pulmonary thrombosis will lead to future combination therapies for hospitalized patients with severe disease that would target the crossroads of inflammatory and coagulation pathways.

Role of Fibrinolysis in the Management of Patients with COVID-19 and Thromboembolic Complications: A Review

An impaired fibrinolytic process has been demonstrated in patients infected with SARS-CoV-2, including those in severe or critical condition. Disruption of fibrinolysis leads to fibrin deposition, which exacerbates inflammation and fibrosis and damages the pulmonary surfactant. Numerous authors point out the different course of coagulopathy in patients with COVID-19. It is reported that they may have a state of secondary hyperfibrinolysis, which may explain, at least in part, the increased incidence of venous thromboembolism, even among those patients already receiving appropriate anticoagulant treatment. This raises the question of whether current guidelines for the prevention and treatment of embolic-thrombotic complications, among patients with severe COVID-19, are sufficient. Some studies show evidence of clinical improvement in patients who have received fibrinolytic therapy, beyond the current indications for its implementation. However, when considering the inclusion of systemic fibrinolytic therapy, the benefits of such treatment should always be weighed over the risk of adverse effects. Thromboelastography and rotational thromboelastometry can be helpful in making such decisions. The purpose of this study was to review the current knowledge regarding fibrinolysis and its role in the treatment of patients with severe COVID-19, including those with thromboembolic complications.

Pulmonary Vascular Thrombosis in COVID-19: Clinical and Morphological Parallels

Aim. We aimed to study the histological and thrombotic changes in lung vessels in patients who died with COVID-19, to access the correlation between anticoagulation therapy (ACT) and thrombotic events (TE), treatment results, clinical and laboratory patients' characteristics.

Material and Methods. We retrospectively analyzed treatment results of patients hospitalized with COVID-19 and lung vessel samples of the deceased patients. Dynamic changes and highest levels of D-dimer and fibrinogen were studied in its correlation with the disease severity according to SOFA score, computer tomographic (CT) results, lung, renal and hepatic dysfunction. The association between different doses of ACT and treatment results, laboratory indicators and thrombotic events was accessed. The histological lung vessels examination was performed using Martius Scarlet Blue (MSB)staining.

Results. 313 patients were included in the study (61 patients died). The median age of hospitalized patients was 60 years (IQR 51-66 years). The frequency of the intravitallyconfirmed TE was 4,8%. The strong statistical association was revealed between D-dimer level and 3-4 points SOFA score, patients' mortality, oxygen support requirement, CT3-CT4 pneumonia, glomerular filtration rate and TE. There was no mortality in patients with D-dimer normal references, but in cases with three times elevation reached 13%, 48,5% - in cases with 3-6 times elevation and 64,6% - in cases with more than 6 times elevation. The strong statistical association was registered between fibrinogen and SOFA score, CT 3-4 pneumonia, patients' mortality. D-dimer and fibrinogen levels demonstrated weak correlation. There was no statistical correlation between prophylactic, intermediate and therapeutic ACT and D-dimer and fibrinogen levels, CT results, patients' mortality. MSBstaining was used in 36 deceased patients tissue samples. 1394 lung vessels were analyzed. Lung vessels thrombi persisted in samples of all 36 patients (100%). Vessels with the diameter 3,5-30 mm were thrombosed in 7%, with the diameter 0,034-0,84 mm - in 48%, with the diameter 0,85-3,4 mm - in 45%. The frequency of thrombi persisted 06 hours, 6-12 hours, 12-18hours, 18-24 hours and more than 24 hours was12%, 14%, 62%, 5% and 7% respectively.

Conclusion. Thrombi of different ages from fresh to organized were observed in one third of lung vessels in all deceased patients. Lung vessels thrombosis plays an important role in pathogenesis and thanatogenesis of COVID-19. The D-dimer level correlates with lung, renal dysfunction, patients' mortality and doesn't show any correlation with ACT and can be accepted as a criterion of lung vessel thrombotic progression.

Findings and inferences from full autopsies, minimally invasive autopsies and biopsy studies in patients who died as a result of COVID19 - A systematic review

Many articles on COVID19 deaths have been published since the pandemic has occurred. On reviewing the articles published until June 2021, the findings were very heterogeneous. Adding to the existing knowledge, there were also some unique observations made in the pathogenesis of COVID19. This review was done to determine the findings obtained and inferences drawn from various studies published globally among patients who died due to COVID19. PRISMA guidelines were used to conduct this systematic review. A search of databases like PubMed, ScienceDirect and Epistemonikos was done. The articles focusing on postmortem sample studies involving full autopsies, minimally invasive autopsies and tissue biopsy studies were screened and searched. The studies included were all the case reports, case series, narrative reviews and systematic reviews obtained in full text and in the English language containing study information, and samples obtained postmortem. The information obtained was tabulated using Microsoft excel sheets. The duplicates were removed at the beginning of the tabulation. Zotero referencing software was used for article sorting and citation and bibliography. Two authors independently reviewed the articles throughout the process to prevent bias. Adding to the heterogeneity of COVID19, the concept of lethality in preexisting disease conditions, the occurrence of secondary bacterial and fungal infections, and other pathogenetic mechanisms uniquely encountered are to be considered in treating the patients. Also, the presence of SARS-CoV-2 postmortem is established and should be considered a hazard.

[Pulmonary artery thrombosis: strategy of anticoagulation]

This review is devoted to the management of primary artery thrombosis (PAT). This disease was always considered only as a part of other venous thromboembolic events, in particular isolated pulmonary embolism (PE). Various studies show that PAT can develop as an independent event without concomitant damage to extra-vessels. PAT is characterized by own typical signs as primary and recurrent event that can determine special strategies of treatment. However, there are no studies devoted to this problem. We can only make some assumptions about PAT anticoagulation (AC) considering data on isolated PE comprising PAT. These data are available in PADIS-PE, ASPIRE, EINSTEIN-PE, Hokusai-VTE studies underlying modern guidelines of various societies. In the absence of studies on PAT AC these guidelines should regulate PAT AC approaches. AC is recommended in all cases of PE except isolated subsegmental PAT in ambulatory patients. Duration of AC depends on risk factors (major or minor). Anticoagulation for PAT following chronic inflammatory diseases is still disputable.

Utility of Non-invasive Cardiac Imaging Assessment in Coronavirus Disease 2019

Coronavirus disease 2019 (COVID-19) was initially regarded as a disease of the lungs, which manifests as an acute respiratory illness and pneumonia, although more recently cardiac complications have been well-characterised. Serological cardiac biomarkers have been used to define acute myocardial injury, with significant elevation of high-sensitivity cardiac troponin (hs-cTn) associated with poor prognosis. Accordingly, 20-25% patients with acute myocardial injury (as defined by an elevated hs-cTn greater than the 99th percentile) have clinical signs of heart failure and increased mortality. An important outstanding clinical question is how best to determine the extent and nature of cardiac involvement in COVID-19. Non-invasive cardiac imaging has a well-established role in assessing cardiac structure and function in a wide range of cardiac diseases. It offers the potential to differentiate between direct and indirect COVID-19 effects upon the heart, providing incremental diagnostic and prognostic utility beyond the information yielded by elevated cardiac biomarkers in isolation. This review will focus on the non-invasive imaging assessment of cardiac involvement in COVID-19.