Ultrasound-Accelerated Thrombolysis Studied for Treatment of Acute Pulmonary Embolism

January 17, 2012—At the International Symposium on Endovascular Therapy in Miami Beach, Florida, Robert J. Kennedy, MD, presented data from a retrospective review of a single-center experience treating 40 consecutive acute pulmonary embolism (PE) patients between 2009 and 2011.

The goal of the study was to evaluate the safety and effectiveness of ultrasound-accelerated thrombolysis for rapid thrombus resolution and improvement of cardiopulmonary function. The study was conducted at Holmes Regional Medical Center in Melbourne, Florida.

Dr. Kennedy stated that upon diagnosis of PE by pulmonary computed tomography angiography or ventilation/perfusion scan, all patients received anticoagulant therapy and treatment with the EkoSonic endovascular system (Ekos Corporation, Bothell, WA). The EkoSonic device was placed into the thrombus to facilitate ultrasound-accelerated thrombolytic infusion at 0.5 or 1 mg/h. Patient outcomes, including clinical improvement, pulmonary artery pressure, thrombus removal (Miller score), and complications, were documented to evaluate treatment success following overnight thrombolytic infusion.

The treated population included 25 men and 15 women with an average age of 60 years. Complete thrombus clearance (90% or better) was achieved in 25 patients, with near-complete clearance (50% to 90%) in the remaining 15 patients. In addition, Dr. Kennedy reported that systolic and mean pulmonary artery pressures decreased significantly from pretreatment measures.  Systolic pulmonary artery pressure after treatment was 37.6 mm Hg after treatment, down from 47.3 mm Hg before (P < 0.001), and mean PA pressure decreased from 26.8 mm Hg to 21.3 mm Hg (P = 0.002). The Miller score improved from 25.3 to 16.9 (P < 0.001). The mean infusion time was 20.3 hours, with a mean tissue plasminogen activator dosage of 34 mg. 

Clinical improvement of symptoms was observed in all 40 patients. No major hemorrhagic complications were reported, and all patients survived to hospital discharge with a median stay of 1 day in the intensive care unit and 9 days overall.

According to Dr. Kennedy, the study demonstrated the safety and effectiveness of ultrasound-accelerated thrombolysis in a population of patients with severe thrombus burden and with increased risk of poor outcomes when left either untreated or undertreated. Treatment success in the study was predictable, with angiographic evidence of thrombus clearance corroborated by significant reduction of pulmonary artery pressure and Miller score, using a low-dose thrombolytic infusion protocol.

“Our analysis of the data on these patients corroborated what we have been observing clinically—that patients with submassive and massive PE tend to have good outcomes when they are treated with ultrasound-accelerated thrombolysis,” commented Dr. Kennedy. “Looking forward, there is a need for multicenter prospective trials to build on the knowledge and experience with this form of treatment and to further evaluate its safety and efficacy. This study focused on the short-term outcomes of these patients. In the future, I would be interested exploring the long-term outcomes in this group of patients.”

Dr. Kennedy also advised that an analysis of the cost effectiveness of this treatment would be useful, especially to determine its impact on length of stay and overall cost of care compared to standard anticoagulation alone.