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JACC Cardiovasc Interv. 2015 Aug 24;8(10):1382-92. doi: 10.1016/j.jcin.2015.04.020.

A Prospective, Single-Arm, Multicenter Trial of Ultrasound-Facilitated, Catheter-Directed, Low-Dose Fibrinolysis for Acute Massive and Submassive Pulmonary Embolism: The SEATTLE II Study.

Author information

  • 1Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts. Electronic address:
  • 2Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
  • 3Cardiovascular Division, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
  • 4Syntactx, New York, New York.
  • 5East Jefferson General Hospital, Metairie, Louisiana.
  • 6Cardiovascular and Interventional Associates, INOVA Alexandria Hospital, Alexandra, Virginia.
  • 7Mt. Carmel East Hospital, Columbus, Ohio.
  • 8Gill Heart Institute, University of Kentucky, Lexington, Kentucky.
  • 9Florida Heart Group, Florida Hospital, Orlando, Florida.
  • 10Holmes Regional Medical Center, Melbourne, Florida.
  • 11Prairie Heart Institute, St. John's Hospital, Springfield, Illinois.
  • 12St. Vincent Medical Group, Indianapolis, Indiana.
  • 13Holy Name Medical Center, Teaneck, New Jersey.
  • 14Vascular Medicine Division, Hartford Hospital, Hartford, Connecticut.
  • 15Lifelink Interventional Center, Memorial Medical Center, Modesto, California.
  • 16River Region Cardiology Associates, Baptist Medical Center, Montgomery, Alabama.
  • 17El Paso Cardiology Associates, PA, Providence Memorial Hospital and Sierra Medical Hospital, El Paso, Texas.
  • 18Leesburg Regional Medical Center, Leesburg, Florida.
  • 19Division of Vascular Intervention Radiology, Department of Radiology, Montefiore Medical Center, Bronx, New York.
  • 20Radiology and Imaging Specialists of Lakeland, Lakeland Regional Medical Center, Lakeland, Florida.
  • 21Christiana Care Center for Heart and Vascular Health, Newark, Delaware.
  • 22The Cardiovascular Care Group, Overlook Medical Center, Summit, New Jersey.
  • 23Macon Cardiovascular Institute, Medical Center of Georgia, Macon, Georgia.
  • 24Miriam Cardiology Inc., The Miriam Hospital, Providence, Rhode Island.
  • 25Stanford University, Stanford, California.
  • 26Fred Hutchinson Cancer Center, Seattle, Washington.



This study conducted a prospective, single-arm, multicenter trial to evaluate the safety and efficacy of ultrasound-facilitated, catheter-directed, low-dose fibrinolysis, using the EkoSonic Endovascular System (EKOS, Bothell, Washington).


Systemic fibrinolysis for acute pulmonary embolism (PE) reduces cardiovascular collapse but causes hemorrhagic stroke at a rate exceeding 2%.


Eligible patients had a proximal PE and a right ventricular (RV)-to-left ventricular (LV) diameter ratio ≥0.9 on chest computed tomography (CT). We included 150 patients with acute massive (n = 31) or submassive (n = 119) PE. We used 24 mg of tissue-plasminogen activator (t-PA) administered either as 1 mg/h for 24 h with a unilateral catheter or 1 mg/h/catheter for 12 h with bilateral catheters. The primary safety outcome was major bleeding within 72 h of procedure initiation. The primary efficacy outcome was the change in the chest CT-measured RV/LV diameter ratio within 48 h of procedure initiation.


Mean RV/LV diameter ratio decreased from baseline to 48 h post-procedure (1.55 vs. 1.13; mean difference, -0.42; p < 0.0001). Mean pulmonary artery systolic pressure (51.4 mm Hg vs. 36.9 mm Hg; p < 0.0001) and modified Miller Index score (22.5 vs. 15.8; p < 0.0001) also decreased post-procedure. One GUSTO (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries)-defined severe bleed (groin hematoma with transient hypotension) and 16 GUSTO-defined moderate bleeding events occurred in 15 patients (10%). No patient experienced intracranial hemorrhage.


Ultrasound-facilitated, catheter-directed, low-dose fibrinolysis decreased RV dilation, reduced pulmonary hypertension, decreased anatomic thrombus burden, and minimized intracranial hemorrhage in patients with acute massive and submassive PE. (A Prospective, Single-arm, Multi-center Trial of EkoSonic® Endovascular System and Activase for Treatment of Acute Pulmonary Embolism (PE) [SEATTLE II]; NCT01513759).

Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.


catheter embolectomy; catheter thrombolysis; fibrinolysis; pulmonary embolism; right ventricular failure; thrombolysis

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