BACKGROUND: Complete resolution of pulmonary vascular obstruction is not totally achieved in patients with acute pulmonary thromboembolism (PE). In this study, we tried to identify the factors associated with residual PE.

MATERIALS AND METHODS: Patients with a diagnosis of acute PE from two centers were retrospectively analyzed. Residual PE was detected by computed tomography (CT) pulmonary angiography. Investigated parameters were unprovoked PE, clinical severity index (pulmonary embolism severity index score), D-dimer, troponin I, central pulmonary embolism, clot burden (Qanadli score), CT indexes of right ventricle (RV) overload (RV/left ventricle and pulmonary artery/aorta), massive PE, coexisting deep venous thrombosis signs and symptoms, and follow-up CT time.

RESULTS: On univariate analysis, follow-up CT time and clot burden at the time of diagnosis were significantly associated with residual PE (P = 0.02 and P = 0.002, respectively). Initial D-dimer levels were higher in patients with residual PE although statistical significance was not reached (P = 0.08). On multivariate analysis, clot burden and follow-up CT time remained significant (hazard ratio [95% confidence interval] of 4.31 [1.31–14.12] and 2.47 [0.92–6.62], respectively).

CONCLUSION: Our results suggest that higher clot burden may be an independent predictor for residual PE along with the timing of follow-up CT.