Cardiovascular parameters to assess the severity of acute pulmonary embolism with computed tomography

Background: Computed tomographic pulmonary angiography (CTPA) has been established as a first-line test in the acute pulmonary embolism (APE) diagnostic algorithm, but the assessment of the severity of APE by this method remains to be explored. Purpose: To retrospectively evaluate right ventricular (RV) dysfunction and severity in patients with APE without underlying cardiopulmonary disease using helical computed tomography (CT). Material and Methods: Seventy-three patients (35 men and 38 women) were divided into two groups according to the clinical findings: severe APE (n=22) and non-severe APE (n=51). Pulmonary artery CT obstruction index was calculated according to the location and degree of clots in the pulmonary arteries. Cardiovascular parameters including RV short axis and left ventricular (LV) short axis, RV short axis to LV short axis (RV/LV) ratio, main pulmonary artery, azygous vein, and superior vena cava diameters were measured. Leftward bowing of the interventricular septum, reflux of contrast medium into the inferior vena cava and azygous vein, and bronchial artery dilatation were also recorded. The results were analyzed by Mann-Whitney U test, x2 test, Spearman's rank correlation coefficient, and the area under the receiver operating characteristic curve (Az). Results: CT obstruction index in patients with severe APE (median 43%) was higher than that of patients with non-severe APE (median 20%). Comparison of cardiovascular parameters between patients with severe and non-severe pulmonary embolism showed significant differences in RV short axis, LV short axis, RV/LV ratio, RV wall thickness, main pulmonary artery diameter, azygous vein diameter, leftward bowing of the interventricular septum, and bronchial artery dilatation. The correlation between CT obstruction indexes and cardiovascular parameters was significant. Spearman's rank correlation coefficient was highest between RV/LV ratio and CT obstruction index. Az values were significantly higher than 0.5 for CT obstruction index, LV short axis, RV/LV ratio, main pulmonary artery diameter, and azygous vein diameter. Conclusion: These results suggest that CTPA is a practical and accurate means for evaluating RV dysfunction of pulmonary embolism in patients without any underlying cardiopulmonary disease and can discriminate between severe and non-severe APE.