Radiology. 2021 Jul 13:210777. doi: 10.1148/radiol.2021210777. Online ahead of print.
Background Pulmonary embolism (PE) commonly complicates SARS-CoV-2 infection but there is heterogeneity in incidence and mortality in the single center reports and risk factors. Purpose To determine the incidence of PE in COVID-19 and its associations with clinical and laboratory parameters. Methods Electronic medical records were searched retrospectively for demographic, clinical and laboratory data and outcomes in patients admitted with COVID-19 at 4 hospitals March-June 2020. PE on CT pulmonary angiography (CTPA) and perfusion scintigraphy was correlated with clinical and laboratory parameters. D-dimer was used to predict PE and the obtained threshold underwent an external validation on 85 hospitalized patients with COVID-19 at a 5th hospital. We also assessed the association between right heart strain and embolic burden in patients with PE undergoing echocardiography. Results Four-hundred-thirteen patients with COVID-19 (230 men, aged 20-98 years, mean + SD = 60+16 years) were evaluated. PE was diagnosed in 25% (102/413, 95%CI: 21%-29%) of hospitalized patients with COVID-19, undergoing CTPA or perfusion scintigraphy. PE was observed in 29% (21/73, 95%CI:19% -41%) of ICU vs. 24% (81/340, 95%CI:20% -29%) of non-ICU patients (p=0.37). PE was associated with male sex(Odds Ratio=OR[95% CI]: 1.7[1.1-2.8], p=0.02), smoking (OR[95% CI]:1.8[1.01-3.4], p=0.04) and increased d-dimer (p<0.001), lactate dehydrogenase (p<0.001), ferritin (p=0.001) and IL-6 (p=0.02). Mortality in hospitalized patients was similar between those with PE and without PE (14%[13/102, 95%CI: 8% - 22%]vs 13%[40/311, 95%CI: 9% - 17%], p=0.98), suggesting that diagnosis and treatment of PE was not associated with excess mortality. D-dimer>1600 ng/mL predicts PE with 100% sensitivity and 62% specificity in an external validation cohort. Embolic burden was higher in patients with right heart strain among the patients with PE undergoing echocardiogram (p=0.03). Conclusion Pulmonary embolism incidence was 25% in patients hospitalized with COVID-19 suspected of PE. D-dimer>1600ng/mL was sensitive for identifying which patients need CTPA. See also the editorial by Ketai.