Correlating computed tomography pulmonary angiography signs of right ventricular strain in pulmonary embolisms to clinical outcomes

INTRODUCTION: Right ventricular strain (RVS) in pulmonary embolism (PE) can be used to stratify risk and direct intervention. The clinical significance of computed tomography pulmonary angiogram (CTPA)-derived radiologic signs of RVS, however, remains incompletely characterized. We retrospectively analyzed a cohort of persons with acute PE to determine which, if any, findings of RVS on CTPA correlate with clinical outcomes. METHODS: All patients with PE diagnosed on CTPA from March 2013 through February 2015 at Lyndon B. Johnson Hospital were identified. Their records were retrospectively reviewed to identify length of stay, intensive care unit (ICU) placement, hemodynamic failure, use of thrombolytics, vasopressor requirement, mechanical ventilation, and attributable mortality. Three radiologists, blinded to clinical outcomes, separately reviewed the cohort's CTPAs to identify signs of RVS – pulmonary trunk size, internal size of the right and left ventricles, paradoxical interventricular septal bowing, inferior vena cava (IVC) contrast reflux, and hepatic vein contrast reflux. RESULTS: In our cohort of 102 persons, 12 demonstrated hemodynamic failure, 13 required ICU placement, 3 received thrombolysis, and 5 had death attributable to PE. The greatest interobserver agreement among radiologists existed for the presence of increased pulmonary trunk size (0.76 kappa by %agreement) and hepatic vein contrast reflux (0.92 kappa by %agreement). A multiple regression analysis found that when 100% radiologist agreement existed, presence of paradoxical intravenous septal bowing predicted thrombolytic usage (P = 0.02), and the presence of IVC reflux predicted attributable mortality (P = 0.03). CONCLUSION: Only IVC contrast reflux was associated with increased mortality, and no other sign of RVS on CTPA correlated with clinical outcomes. This suggests that most signs of RVS on CTPA do not reliably predict PE severity. Therefore, RVS seen by CTPA should be used cautiously in weighing the decision to initiate thrombolytics.