The study concluded that treatment with ultrasound-facilitated catheter-directed low-dose thrombolysis 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, a serious adverse experience related to full-dose thrombolysis treatment.
The SEATTLE II study was a prospective, single-arm, multi-center trial designed to evaluate the safety and effectiveness of ultrasound-facilitated catheter-directed low-dose thrombolysis, using the EKOS EkoSonic Endovascular System.
One-hundred fifty (150) patients diagnosed as acute massive (N=31) or submassive (N=119) PE were enrolled. Patients received low dose (24 mg) of tPA (thrombolytic) for 24 hours with a unilateral catheter or for 12 hours with bilateral catheters. The size of the right heart measured as RV/LV ratio significantly decreased from 1.55 to 1.13 (p<0.0001) by 48 hours after start of treatment.
For patients with severe PE, the mortality rate is nearly one third1. In the SEATTLE II study 31 patients presented to the emergency room with massive PE, syncope and hypotension. All 31 survived the 30-day follow up period. Of 150 patients in the study, one death was directly attributed to PE.
There were no intracranial hemorrhages and no fatal bleeding events. Major bleeds occurred in 15 patients and were comprised of one severe bleed and 16 moderate bleeds. Six of the major bleeds occurred in patients with co-morbidities known to be associated with an increased risk of bleeding during thrombolytic therapy.
"The SEATTLE II findings establish a new rationale for considering ultrasound-facilitated catheter-directed low-dose thrombolysis in both massive and submassive PE," said Gregory Piazza, MD, MS Assistant Professor of Medicine, Harvard Medical School, Staff Physician, Cardiovascular Division, Brigham and Woman’s Hospital (Boston, MA), and Principal Investigator for SEATTLE II.
"The SEATTLE II and ULTIMA trials add to the body of evidence showing treatment with the EkoSonic Endovascular System improves the standard of care for patients with acute pulmonary embolism," said Matt Stupfel, General Manager of EKOS Corporation.
EKOS has shown a continued commitment to clinical research in PE. The ULTIMA trial, published January 2014 in Circulation, demonstrated that EKOS treatment was clinically superior to anticoagulation with heparin alone in reversing right ventricular enlargement at 24 hours, without an increase in bleeding complications.
Building on the success of SEATTLE II and ULTIMA for treatment of PE, EKOS continues to improve and enhance clinical science knowledge by launching the next study, OPTALYSE PE, to better understand the optimal dose of thrombolytic and duration of its treatment.
