Acute Pulmonary Embolism Associated with COVID-19 Pneumonia Detected with Pulmonary CT Angiography

Introduction

Chest CT plays an important role in optimizing the treatment of patients with coronavirus disease 2019 (COVID-19) while also eliminating alternate diagnoses or added pathologic conditions, particularly for acute pulmonary embolism (1). A few studies and isolated clinical cases of COVID-19 pneumonia with coagulopathy and pulmonary embolus have recently been published (2–4). The main objective of our study was to evaluate pulmonary embolus in association with COVID-19 infection by using pulmonary CT angiography.

Materials and Methods

This retrospective study was approved by our institutional review board. It followed the ethical guidelines of the Declaration of Helsinki. The requirement for written informed consent was waived. Three authors (F.G., J.B., P.C.) had access to the study data. No author has any conflict of interest to declare in relation to this study.

Results

Of 2003 patients diagnosed with COVID-19, 280 were hospitalized during the study period. Of these 280 patients, 129 (46%) underwent CT a mean of 9 days ± 5 (standard deviation) after symptom onset. Twenty-nine patients underwent unenhanced chest CT due to contraindication to iodinated contrast material or nonsevere clinical features; thus, these patients were excluded. Finally, 100 patients with COVID-19 infection and severe clinical features were included and examined with contrast material–enhanced CT (Fig 1). The mean age of the included patients was 66 years ± 13, and there were 70 men and 30 women (Table).

Figure 1:

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Figure 2:

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Patient Characteristics

Of the 100 patients meeting the inclusion criteria, 23 (23%, [95% confidence interval: 15%, 33%]) had acute pulmonary embolism (Fig E2, Appendix E1 [online]). Patients with pulmonary embolus were more frequently in the critical care unit than those without pulmonary embolus (17 [74%] vs 22 [29%] patients, respectively; P < .001), required mechanical ventilation more often (15 of 23 patients [65%] vs 19 of 77 patients [25%], P < .001), and had longer delay from symptom onset to CT diagnosis of pulmonary embolus (mean, 12 days ± 6 vs 8 days ± 5, P < .001) (Table). At multivariable analysis, requirement for mechanical ventilation (odds ratio = 3.8 [95% confidence interval: 1.02, 15], P = .049) remained associated with acute pulmonary embolus (Table E3, Appendix E1 [online]).

Discussion

Our study points to a high prevalence of acute pulmonary embolism in patients with coronavirus disease 2019 (23% [95% confidence interval: 15%, 33%]). Pulmonary embolus was diagnosed a mean of 12 days from symptom onset. Patients with pulmonary embolus were more likely to require care in the critical care unit and to require mechanical ventilation compared with those without pulmonary embolus.

Current guidelines (1,5,6) recommend performing unenhanced chest CT to assess the COVID-19 CT pattern and its extension. However, previous reports suggested coagulopathy associated with COVID-19 infection (2,3). Furthermore, these patients have frequent risk factors for pulmonary embolus (eg, mechanical ventilation, intensive care unit admission). Therefore, we routinely performed contrast-enhanced CT for patients with COVID-19 with severe clinical features to evaluate the lung parenchyma as well as to evaluate other complications that may result in respiratory distress.

Our results showed frequent (23%) pulmonary embolus in patients with COVID-19. At multivariable analysis, pulmonary embolus was associated with invasive mechanical ventilation and male sex. Interestingly, extent of lesions was not associated with pulmonary embolus. We acknowledge the preliminary nature of these findings, including its retrospective nature and limited sample size. Important clinical markers were not available that may explain or be associated with pulmonary embolus, including d-dimer level (only 22 of the 100 patients had d-dimer levels available). Nevertheless, our results suggest that patients with severe clinical features of COVID-19 may have associated acute pulmonary embolus. Therefore, the use of contrast-enhanced CT rather than routine unenhanced CT may be considered for these patients.