Radiological cardiothoracic ratio as a potential predictor of right ventricular enlargement in patients with suspected pulmonary embolism due to COVID-19

ABSTRACT

Objective. Cases of pulmonary embolism are observed in the course of COVID-19. Right ventricular enlargement is a negative prognostic factor of pulmonary embolism. The cardiothoracic ratio is a routine parameter in the cardiac assessment in chest radiology. Purpose. The aim of the study was to determine the usefulness of the radiological cardiothoracic ratio (CTR) as a predictor of right ventricular enlargement in patients with suspected pulmonary embolism during COVID-19. Material and method. The study group consisted of 61 patients with confirmed COVID-19, suspected of pulmonary embolism based on physical examination and laboratory tests (age 67.18 ± 12.47 years). Computed tomography angiography (CTA) of pulmonary arteries and chest radiograph in AP projection with cardiothoracic ratio assessment were performed in all patients. Right ventricular enlargement was diagnosed by the ratio of right ventricular to left ventricular (RV/LV) dimensions in pulmonary CTA with 2 cut-off points ≥0.9 and ≥1.0. Heart's silhouette enlargement was found when CTR on the chest radiograph in the projection AP >0.55. Results. The mean values of RV/LV and CTR in the studied group were 0.96 ± 0.23 and 0.57 ± 0.05. Pulmonary embolism was diagnosed in 45.9%. Right ventricular enlargement was documented in 44.3% or 29.5% depending on the adopted criterion RV/LV ≥0.9 or RV/LV ≥1.0. Heart's silhouette enlargement was found in 60.6%. Patients with confirmed pulmonary embolism (PE+) had significantly higher RV/LV ratio and CTR than patients with excluded pulmonary embolism (PE-) (RV/LV PE+ 1.08 ± 0.24, PE- 0.82 ± 0.12;CTR PE+ 0.60 ± 0.05, PE- 0.54 ± 0.04;p < 0.05). The correlation analysis showed a statistically significant positive correlation between RV/LV ratio and CTR (r = 0.59, p < 0.05). Based on the ROC curves, CTR values were determined as the optimal cut-off points for the prediction of right ventricular enlargement (RV/LV ≥0.9 or RV/LV ≥1.0), being 0.54 and 0.55, respectively. The sensitivity, specificity, and accuracy of the CTR criterion >0.54 as a predictor of RV/LV ratio ≥0.9 was 0.412, 0.963, and 0.656, respectively, while the CTR criterion >0.55 as a predictor of RV/LV ratio ≥1.0 was 0.488, 0.833, and 0.590, respectively. Conclusions. In patients with suspected pulmonary embolism during COVID-19, radiographic cardiothoracic ratio may be a predictor of right ventricular enlargement, especially a negative predictor of right ventricular enlargement in case of lower CTR values.