SEATTLE II: Ultrasound-facilitated thrombolysis safe, effective for acute PE

WASHINGTON — Ultrasound-delivered, catheter-directed, low-dose thrombolysis using the EKOS EkoSonic endovascular system was associated with improved right ventricle function and reduced pulmonary hypertension and intracranial hemorrhage risk among patients with acute pulmonary embolism in the SEATTLE II study.

Results of the prospective, single-arm, multicenter trial were presented by Gregory Piazza, MD, clinical instructor in medicine at Harvard Medical School, during the American College of Cardiology Scientific Sessions. Researchers evaluated the efficacy of the EkoSonic endovascular system in 31 patients with acute massive pulmonary embolism (PE) and 119 patients with sub-massive PE. All participants had proximal PE and a dilated right ventricle (RV/LV ratio ≥0.9). The trial used a dose of 24 mg tissue plasminogen activator (tPA), administered either as 1 mg/hour for 24 hours with a unilateral catheter or 1 mg/hour/catheter for 12 hours with bilateral catheters, according to a press release.

Mean RV/LV ratio decreased significantly, from 1.55 before thrombolysis to 1.13 at 48 hours after thrombolysis (P<.0001). At the 30-day follow-up, there were no deaths reported among patients with massive PE. In the overall cohort, there was one death directly attributed to PE, according to the release.

Major bleeding was reported in 17 patients, including one severe bleed and 16 moderate bleeds. Six of the major bleeds occurred in patients with comorbidities known to be associated with increased bleeding risk during thrombolytic therapy. There were no reports of fatal bleeding events or intracranial hemorrhage.

“This trial represents a breakthrough in demonstrating the safety and efficacy of thrombolytic therapy for acute PE,” principal investigator Samuel Z. Goldhaber, MD, professor of medicine at Harvard Medical School and director of the Thrombosis Research Group at Brigham and Women’s Hospital, said in the press release. “The reduction of the RV/LV ratio by 0.42 is substantial and clinically significant, without any intracranial hemorrhage and using a much-reduced lytic dose. These findings establish a new rationale for considering thrombolysis in both massive and sub-massive PE.”

The system is indicated in the United States for controlled and selective infusion of physician-specific fluids, including thrombolytics, in the peripheral vasculature. In Europe, the system is intended for the treatment of PE among patients with ≥50% clot burden in one or both main pulmonary arteries or lobar pulmonary arteries, and evidence of right ventricle dysfunction, according to the release.

For more information:

Piazza G. Abstract #407-04. Presented at: American College of Cardiology Scientific Sessions ; March 29-31, 2014; Washington, D.C.

Disclosure: EKOS Corp. provides research grants for venous thromboembolism research to Brigham and Women’s Hospital. Piazza and Goldhaber report no relevant financial disclosures.