Imaging approach to COVID-19 associated pulmonary embolism

Arterial Thrombosis in Acute Respiratory Infections: An Underestimated but Clinically Relevant Problem

During the COVID-19 pandemic, there was increased interest in the issue of thrombotic complications of acute respiratory infections. Clinical reports and pathological studies have revealed that thrombus formation in COVID-19 may involve the venous and arterial vasculature. As thrombotic complications of infectious respiratory diseases are increasingly considered in the context of COVID-19, the fact that thrombosis in lung diseases of viral and bacterial etiology was described long before the pandemic is overlooked. Pre-pandemic studies show that bacterial and viral respiratory infections are associated with an increased risk of thrombotic complications such as myocardial infarction, ischemic stroke, pulmonary embolism, and other critical illnesses caused by arterial and venous thrombosis. This narrative review article aims to summarize the current evidence regarding thrombotic complications and their pathogenesis in acute lower respiratory tract infections.

Thromboembolic Disease and COVID-19: Experience of a University and Emergency Hospital During the Pandemic

BACKGROUND

COVID-19 leads to vasculopathy, which is linked to both a prothrombotic state and an impaired immune response. A notable increase in pulmonary embolism (PE) and deep venous thrombosis (DVT) has been documented.

METHODS

We conducted a retrospective analysis of all patients who were admitted with venous thromboembolic disease (VTD) in the largest university and emergency hospital in Romania, between May 1, 2020, and April 30, 2021. Patients were categorized into two groups based on the presence (Group 1) or absence (Group 2) of COVID-19 virus infection at the time of admission. The aim of this study was to assess the characteristics of VTD in COVID-19 patients and to compare the clinical and paraclinical parameters of the Group 1 and Group 2 patients admitted for VTD in an emergency hospital during the first two waves of the pandemic (12 months). We compared clinical, biological, and imaging parameters and applied binary logistic analysis for the predictive models.

RESULTS

A total of 198 patients were diagnosed with VTD (at admission or during the hospitalization); out of 33,373 patients hospitalized, 43 (21.7%) were diagnosed with COVID-19 (12.2% with mild COVID-19, 61.0% moderate, and 26.8% severe). Group 1 showed higher heart rates and leukocytes, more severe pulmonary changes (p<0.05), higher N-terminal-pro-B-type natriuretic peptide (NTproBNP), and high sensitivity troponin I (hs-cTnI) (p>0.05). Not reaching statistical significance, the mortality tended to be higher in Group 1. These patients were admitted to the intensive care units for longer (3.5 vs. 1.5 days, p > 0.05). The minimum value of thrombocytes during hospitalization was inversely correlated with the risk of death. Interestingly, the Pulmonary Embolism Severity Index (PESI) score was not predictive for in-hospital death in Group 1, but only in Group 2 (area under the curve (AUC) = 0.821, CI 0.689-0.952).

CONCLUSION

Individuals with severe manifestations of COVID-19 remain vulnerable to developing VTD and are prone to adverse outcomes. The efficacy of PESI as a predictive tool for in-hospital death is non-significant. Further refinement of specific predictive scores tailored to VTD associated with COVID-19 is needed.

Emergency Presentations of Coronavirus Disease (COVID-19): A Review of the Literature and Radiologic Perspective

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the debilitating global pandemic known as Coronavirus disease (COVID-19). In this paper, we highlight the widespread manifestations and complications across disease systems. In addition, we present their relevant imaging findings to inform appropriate investigations and management in patients presenting to the Emergency Department with COVID-19 and its respective sequalae. Of note, we outline considerations for diagnosis of long COVID, an important medium to long term sequalae in patients with previous COVID-19 infections.

Thrombotic Long-Term Consequences of SARS-CoV-2 Infection in Patients with Compensated Cirrhosis: A Propensity Score-Matched Analysis of a U.S. Database

BACKGROUND

Cirrhosis causes an imbalance in the coagulation pathway and leads to a tendency for both bleeding and clotting. SARS-CoV-2 has been reported to be associated with a hypercoagulable state. This study examines SARS-CoV-2's impact on hemostasis in compensated patients with cirrhosis.

METHODS

We analyzed the US Collaborative Network, which comprises 63 HCOs in the U.S.A. Compensated cirrhosis patients were split into two groups: SARS-CoV-2-positive and -negative. Patients' baseline characteristics were used in a 1:1 propensity score-matched module to create comparable cohorts. We compared the risk of portal vein thrombosis (PVT), deep venous thrombosis (DVT), and pulmonary embolism (PE) at 6 months, and 1 and 3 years.

RESULTS

Of 330,521 patients, 27% tested positive and 73% remained negative. After PSM, both cohorts included 74,738 patients. Patients with SARS-CoV-2 had a higher rate of PVT compared to those without at 6 months (0.63% vs 0.5%, p < 0.05), 1 year (0.8% vs 0.6%, p < 0.05), and 3 years (1% vs. 0.7%, p < 0.05), a higher rate of DVT at 6 months (0.8% vs. 0.4%, p < 0.05), 1 year (1% vs. 0.5%, p < 0.05), and 3 years (1.4% vs. 0.8%, p < 0.05), and a higher rate of PE at 6 months (0.6% vs. 0.3%, p < 0.05), 1 year (0.7% vs. 0.4%, p < 0.05), and 3 years (1% vs. 0.6%, p < 0.05).

CONCLUSIONS

The presence of SARS-CoV-2 infection in patients with compensated cirrhosis was associated with a higher rate of PVT, DVT, and PE at 6 months, and 1 and 3 years.

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.

In Situ Pulmonary Arterial Thrombosis: Literature Review and Clinical Significance of a Distinct Entity

Filling defects identified in the pulmonary arterial tree are commonly presumed to represent an embolic phenomenon originating from thrombi formed in remote veins, particularly lower-extremity deep venous thrombosis (DVT). However, accumulating evidence supports an underappreciated cause for pulmonary arterial thrombosis (PAT), namely, de novo thrombogenesis-whereby thrombosis arises within the pulmonary arteries in the absence of DVT. Although historically underrecognized, in situ PAT has become of heightened importance with the emergence of SARS-CoV-2 infection. In situ PAT is attributed to endothelial dysfunction, systemic inflammation, and acute lung injury and has been described in a range of conditions including COVID-19, trauma, acute chest syndrome in sickle cell disease, pulmonary infections, and severe pulmonary arterial hypertension. The distinction between pulmonary embolism and in situ PAT may have important implications regarding management decisions and clinical outcomes. In this review, we summarize the pathophysiology, imaging appearances, and management of in situ PAT in various clinical situations. This understanding will promote optimal tailored treatment strategies for this increasingly recognized entity.

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.

CTPA ordering trends in local emergency departments: are they increasing and did they increase as a result of COVID-19?

PURPOSE

Ordering trends for computed tomographic pulmonary angiogram (CTPA) studies by local emergency departments were assessed, along with the impact of the COVID-19 pandemic on these ordering trends and CTPA positivity rates.

METHODS

A retrospective quantitative analysis was performed on all CTPA studies ordered between February 2018 - January 2022 by three local tertiary care emergency rooms to investigate for pulmonary embolism. Data collected from the first two years of the COVID-19 pandemic was compared to the two years prior to the pandemic to assess for significant changes in ordering trends and positivity rates.

RESULTS

The overall number of CTPA studies ordered increased from 534 studies in 2018-2019 to 657 in 2021-2022 and the rate of positive diagnosis of acute pulmonary embolism varied between 15.8% to 19.5% over the four years studied. There was no statistically significant difference in the number of CTPA studies ordered when comparing the first two years of the COVID-19 pandemic to the two years immediately prior; however, the positivity rate was significantly higher during the first two years of the pandemic.

CONCLUSION

Over the studied period from 2018-2022, the overall number of CTPA studies ordered by local emergency departments has increased, in line with literature reports from other locations. There was also a correlation between the onset of the COVID-19 pandemic and CTPA positivity rates, possibly secondary to the prothrombotic nature of this infection or the increase in sedentary lifestyles during lockdown periods.

Imaging approach to COVID-19 associated pulmonary embolism

The novel coronavirus disease-2019 (COVID-19) illness and deaths, caused by the severe acute respiratory syndrome coronavirus-2, continue to increase. Multiple reports highlight the thromboembolic complications, such as pulmonary embolism (PE), in COVID-19. Imaging plays an essential role in the diagnosis and management of COVID-19 patients with PE. There continues to be a rapid evolution of knowledge related to COVID-19 associated PE. This review summarises the current understanding of prevalence, pathophysiology, role of diagnostic imaging modalities, and management, including catheter-directed therapy for COVID-19 associated PE. It also describes infection control considerations for the radiology department while providing care for patients with COVID-19 associated PE.