Abstract
Reflux of contrast medium into the inferior vena cava (IVC) on computed tomography pulmonary angiogram (CTPA) is an independent risk factor for mortality in patients with acute pulmonary embolism (PE). This study's aim was to determine if reflux into the IVC correlates with objective scores of clinical risk in acute PE. Patient-level data were collected for adults diagnosed with acute PE by CTPA at University of California, San Diego Health between January 1 and June 30, 2023. Contrast reflux into the IVC was graded on a 4-point scale. The primary endpoint was the correlation between reflux severity and risk for clinical deterioration as measured by the National Early Warning Score (NEWS). The secondary endpoint was interobserver reliability grading reflux amongst 16 reviewers. Fifty-six subjects with acute PE were included. Extent of contrast reflux into the IVC correlated with NEWS (Spearman's ρ 0.2932; p = 0.028). Subjects with grade 3 reflux had increased NEWS (7.80) compared to those with reflux grades 0 (3.63; p = 0.014) or 1 (4.29; p = 0.05). NEWS was elevated in those with contrast below the diaphragm compared to those without when grading was pooled (p = 0.036). Interobserver reliability for reflux grading was "moderate" (κ = 0.58), yet increased to "almost perfect" (κ = 0.87) for pooled grading. Contrast reflux into the IVC during acute PE correlates with risk for clinical deterioration, as reflected by NEWS. Simplification of grading to contrast above or below the diaphragm improves reliability without compromising this relationship.