Ultrasound-assisted catheter-directed thrombolysis for pulmonary embolism: current evidence, limitations, and future directions

Pulmonary embolism (PE) is the third leading cause of cardiovascular death globally and continues to carry high rates of morbidity and mortality despite advances in therapy. While risk stratification helps guide treatment for both low- and high-risk patients, optimal management of intermediate-risk PE remains unclear. Although contemporary AHA/ACC guidelines introduce more granular clinical categories to better define risk and guide treatment selection within this heterogeneous population, uncertainty persists. Systemic fibrinolysis poses bleeding risks, whereas anticoagulation alone may not be sufficient to prevent clinical deterioration. Catheter-based approaches, such as ultrasound-assisted catheter-directed thrombolysis (UACDT), have therefore emerged as potential options that deliver lower-dose fibrinolytics directly into the pulmonary arteries. However, much of the existing literature combines UACDT with other catheter-based interventions, making it difficult to isolate its specific contribution. The data are also heterogeneous, limiting cross-study comparisons. This review summarizes the current evidence, influential clinical trials, and ongoing studies on UACDT, with a focus on its therapeutic potential, safety considerations, limitations, and evolving role in the management of intermediate-risk PE. A literature search was conducted using PubMed, Embase, and ClinicalTrials.gov from inception through early 2026, with supplementary searches performed using Google Scholar.