The SEATTLE II study, which will investigate the safety and efficacy of ultrasound accelerated thrombolysis with the EkoSonic Endovascular System (EKOS Corporation) for the treatment of massive and submassive pulmonary embolism, has completed enrolment. SEATTLE II is a 150-patient, single-arm prospective study measuring the rapid reduction in right heart strain in a patient population with both massive and submassive pulmonary embolism.
Robert W Hubert, president and CEO of EKOS Corporation cited US patient statistics: “There are over 600,000 cases of pulmonary embolism each year alone of which upwards of 45% are considered major having significant clot in one or both pulmonary arteries. This clot burden interferes with the heart’s ability to pump blood into the lungs for oxygenation, causing enlargement of the right side of the heart. Not removing the clot burden quickly may result in permanent pulmonary hypertension or even death.”
Up to this point, the current standard of care has been anticoagulation or in the most serious cases intravenous thrombolytics. Anticoagulation therapy does not dissolve clots, but rather helps prevent further clots from forming. Intravenous thrombolytics do help dissolve clot but the high dosage required causes serious bleeding in as many as 20% of patients and causes haemorrhagic stroke in 1% to 3% of patients.
Samuel Z Goldhaber, professor of Medicine, Harvard Medical School and director, Venous Thromboembolism Research Group, Brigham and Woman’s Hospital, Boston, USA, serves as principal investigator for SEATTLE II.
Goldhaber noted, “It is almost unheard of to exceed ambitious enrolment goals in any clinical trial. With enrolment of 150 patients from June 2012 through February 2013, SEATTLE II recruited patients at a galloping pace that was more than double our expected enrolment rate. This study utilised EKOS in a uniform protocol of thrombolytic (tPA) drug dose and drug infusion time. We instituted uniform inclusion and exclusion criteria, and we amassed an impressive safety record, especially considering that our patient population was gravely ill with either massive or submassive pulmonary embolism. We fully expect to see confirmation of the haemodynamic benefit of rapid aggressive EKOS therapy suggested by previously reported single-centre studies.”
Thrombolysis can prevent death and haemodynamic collapse in patients with pulmonary embolism. Goldhaber points out, “The challenge has been to minimise the major bleeding complication of intracranial haemorrhage which occurs 10 times more often with intravenous administered thrombolysis than with heparin alone. It is no surprise that EKOS, utilising less than one-fourth of the standard thrombolytic dose, shows a much improved safety record compared with traditional therapy.”
Hubert added, “We expect this study to continue demonstrating the safety and effectiveness of the EKOS device for the treatment of pulmonary embolism, as did our first trial (ULTIMA), a randomised controlled trial of 59 patients recently presented at the American College of Cardiology annual meeting in San Francisco.”