Background: The purpose of this study was to evaluate whether measuring the ratio of descending aortic enhancement (DAE) to main pulmonary artery enhancement (MPAE) on pulmonary computed tomography angiography (PCTA) can predict poor outcome in patients with acute massive or submassive pulmonary embolism (PE). Methods: We retrospectively, reviewed computed tomgraphy findings and charts of 37 patients with acute PE and right ventricular dysfunction. We divided the enrolled patients into 3 groups; group Ia (n=8), comprised of patients with major adverse event (MAE); group Ib (n=5), consisted of those with PE-related MAE; and group II (n=29), those without MAE. We analyzed the right ventricular diameter (RVD)/left ventricular diameter (LVD) and DAE/MPAE on PCTA. Results: For observer 1, RVD/LVD in group Ia ($1.9{pm}0.36$ vs. $1.44{pm}0.38$, p=0.009) and group Ib ($1.87{pm}0.37$ vs. $1.44{pm}0.38$, p=0.044) were significantly higher than that of group II. For observer 2, RVD/LVD in group Ia ($1.71{pm}0.18$ vs. $1.41{pm}0.47$, p=0.027) was significantly greater than that of group II, but RVD/LVD of group Ib was not ($1.68{pm}0.2$ vs. $1.41{pm}0.47$, p=0.093). For both observers, there was a significant difference of DAE/MPAE between group Ib and group II ($0.32{pm}0.15$ vs. $0.64{pm}0.24$, p=0.005; $0.34{pm}0.16$ vs. $0.64{pm}0.22$, p=0.004), but no significant difference of DAE/MPAE between group Ia and group II ($0.51{pm}0.3$ vs. $0.64{pm}0.24$, p=0.268; $0.53{pm}0.29$ vs. $0.64{pm}0.22$, p=0.302). Intra-class correlation coefficient (ICC) for the measurement of DAE/MPAE (ICC=0.97) was higher than that of RVD/LVD (ICC=0.74). Conclusion: DAE/MPAE measured on PCTA may predict PE-related poor outcomes in patients with massive or submassive PE with an excellent inter-observer agreement.