Pulmonary Thromboembolic Disease in Patients with COVID-19 Undergoing Computed Tomography Pulmonary Angiography (CTPA): Incidence and Relationship with Pulmonary Parenchymal Abnormalities
Purpose This study aims to report the incidence, severity and extent of pulmonary thromboembolic disease (PTD) in patients with confirmed COVID-19 who have undergone CT pulmonary angiography (CTPA) in a tertiary centre. Materials and Methods This is a retrospective analysis of all patients undergoing CTPA between 23rd March 2020 and 19th April 2020 in a tertiary centre. The presence of PTD, location and involved pulmonary lobes were documented. The pattern and extent of pulmonary parenchymal
... nary parenchymal abnormalities including the presence of fibrosis, lymph node enlargement and pleural effusion were evaluated by two experienced observers independently and consensus was achieved for the most disparate results. Inter-observer agreement was assessed using Kappa statistics. Student t-test, Chi square and Mann-Whitney U tests were used to compare imaging features between PTD and non-PTD sub-groups. Results During the study period, 2157 patients were confirmed with COVID-19, 297/2157 (13.8%) had CT imaging, 100/2157 (4.6%) were CTPA studies, 93 studies were analysed, excluding sub-optimal studies. Overall incidence of PTD was 41/93 (44%) with a third of patients showing segmental and subsegmental PTD (n=28/93, 30%,). D-dimer was elevated in 90/93 (96.8%) of cases. High Wells score did not differentiate between PE and non-PE groups (p=0.801). The inter-observer agreement was fair (Kappa=0.659) for parenchymal pattern and excellent (Kappa = 0.816) for severity. Lymph node enlargement was found in 34/93 of cases (36.6%) with 29/34 (85.3%) showing no additional source of infection. Fibrosis was seen in 16/93 (17.2%) of cases, mainly demonstrating fibrotic organising pneumonia. Conclusion There is a high incidence of PTD in COVID -19 patients undergoing CTPA, complicated by lack of a valid risk stratification tool. Our data indicates a much higher suspicion of PTD is needed in severe COVID-19 patients. The concomitant presence of fibrotic features on CT indicates the need for follow-up for evaluation of chronic pulmonary complications.