Published SEATTLE II Results Support Low-Dose Thrombolysis With EkoSonic System for Acute PE

August 24, 2015—Ekos Corporation, a BTG International group company, announced that the results of the SEATTLE II trial were published by Gregory Piazza, MD, et al in the Journal of the American College of Cardiology (JACC): Cardiovascular Interventions (2015;8:1382–1392).

The study concluded that treatment with ultrasound-facilitated, catheter-directed, low-dose thrombolysis using the company’s EkoSonic endovascular system for acute pulmonary embolism (PE) improves right heart function, reduces blood clot size, and decreases pulmonary hypertension in patients with intermediate- to high-risk PE. Importantly, no patient experienced intracranial hemorrhage, which can be a serious adverse experience related to full-dose thrombolysis treatment. 

Dr. Piazza, who is one of the Principal Investigators for SEATTLE II, commented in Ekos’ press release, “The SEATTLE II findings establish a new rationale for considering ultrasound-facilitated, catheter-directed, low-dose thrombolysis in both massive and submassive PE. Without any intracranial hemorrhage and using a much reduced lytic dose, a substantial and clinically meaningful reduction of the right ventricular/left ventricular ratio was achieved.” Dr. Piazza is Assistant Professor of Medicine at Harvard Medical School and Staff Physician, Cardiovascular Division, at Brigham and Woman’s Hospital in Boston, Massachusetts.

In March 2014, Dr. Piazza presented the SEATTLE II trial at ACC.14: the 63rd annual scientific session of the American College of Cardiology in Washington, DC. In May 2014, Ekos announced US Food and Drug Administration clearance of the EkoSonic endovascular system for the ultrasound-facilitated, controlled, and selective infusion of physician-specified fluids (including thrombolytics) into the vasculature for treating PE.

The SEATTLE II study was a prospective, single-arm, multicenter trial designed to evaluate the safety and effectiveness of ultrasound-facilitated, catheter-directed, low-dose thrombolysis using the EkoSonic system. The study enrolled 150 patients with acute massive (n = 31) or submassive (n = 119) PE. Patients received a low-dose (24 mg) thrombolytic (tissue plasminogen activator) for 24 hours with a unilateral catheter or for 12 hours with bilateral catheters. The size of the right heart, measured as right ventricular/left ventricular ratio, significantly decreased from 1.55 to 1.13 (P < .0001) at 48 hours after the treatment was initiated.

Additionally, 31 patients in SEATTLE II presented to the emergency department with massive PE, syncope, and hypotension. All 31 patients survived the 30-day follow-up period. Of the 150 patients in the study, one death was directly attributed to PE. There were no intracranial hemorrhages and no fatal bleeding events. Major bleeds (one severe, 16 moderate) occurred in 15 patients. Ekos reported that six of the major bleeds occurred in patients with comorbidities known to be associated with an increased risk of bleeding during thrombolytic therapy.