Background: Given the bleeding risk associated with full-dose intravenous thrombolytic treatment and the absence of randomized clinical trial evidence, current guidelines do not recommend reperfusion treatments as first-line therapy for intermediate-high risk (IHR) pulmonary embolism (PE). The aim of this study was to evaluate the effectiveness and safety of ultrasound-assisted catheter-directed thrombolysis (USAT) compared to anticoagulation therapy alone in patients with IHR PE.

Methods: A total of 425 patients diagnosed with acute PE and determined as IHR, 203 of whom underwent USAT, and 222 patients receiving only anticoagulants as the control group, were included. Baseline and post-treatment right ventricle (RV) function in echocardiography, tomographic RV/left ventricle (RV/LV) ratio, Qanadli score (Qs), and % changes from baseline were taken as primary effectiveness outcomes. For safety outcomes, major and minor bleeding and in-hospital all-cause death were adopted. Propensity score analysis was performed to reduce confounders and bias.

Results: The USAT treatment was found to be associated with improved RV function and decreased Qs, but no significant effect was observed on the RV/LV ratio and its change. Bleeding events were more frequent in the USAT group (P < .001 for both), and no difference was observed in terms of mortality.

Conclusion: The study, based on real-life data, has shown that a moderate-dose, slow-infusion tissue-type plasminogen activator regimen is superior to anticoagulant therapy alone in terms of reducing pulmonary arterial thrombus burden, restoring RV dysfunction, and improving clinical outcomes in acute PE patients at IHR. However, it has also resulted in a slight increase in bleeding events.