A study presented at the American College of Cardiology's Annual Scientific Session (ACC.26) on Mar. 28 found that delivering low doses of clot-buster drugs directly to the site of a pulmonary embolism (PE) using a catheter and ultrasound led to significantly better outcomes than standard systemic anticoagulants. The targeted catheter-based method reduced early PE-related death, circulatory collapse, or recurrence by more than 60%.
Pulmonary embolism occurs when a blood clot blocks a lung blood vessel, which can cause severe damage or death. At least 20-25% of PE cases are considered high risk for cardiopulmonary failure, with real-world death rates reaching up to 15%. While clot-buster medications can dissolve clots, they also carry risks such as brain bleeding and are typically reserved for only the most critical cases.
The trial enrolled 544 patients across sites in the United States and eight European countries who had intermediate-risk PE with additional signs of severity like high heart rate or low oxygen saturation. Participants were randomly assigned either to receive ultrasound-facilitated catheter-directed thrombolysis or standard systemic anticoagulation. Both groups followed standardized protocols for medication administration and rescue treatment if needed.
After 30 days, researchers reported that only 4% of those receiving the catheter-based treatment experienced serious complications compared to 10.3% in the control group—a significant difference favoring the new approach due mainly to fewer instances of cardiorespiratory decompensation or collapse among those treated with catheters. No brain bleeds occurred in either group, and there was no significant difference in deaths from any cause or major bleeding between groups.
Researchers said that this ultrasound-facilitated method is feasible for physicians experienced in cardiovascular interventions at hospitals equipped with suitable facilities and teams available around-the-clock. "The results regarding effectiveness are very convincing," Konstantinides said. "In addition, the study offers a precedent for how to evaluate the effects of catheter treatments for PE." He added that as more trials are conducted on different types of catheter treatments, stronger evidence will inform future guidelines.
Patient outcomes will continue to be tracked up to one year after treatment to assess long-term survival rates and quality-of-life differences between groups. Researchers noted that results might vary among more diverse populations and cautioned against applying these findings broadly across all forms of catheter-based PE treatments.
