The EKOS™ Endovascular System is the most studied device in the pulmonary embolism space

Clinical Data

Pulmonary Embolism

EKOS Clinical Evidence

The EKOS™ Endovascular System is the most studied device in the Pulmonary Embolism space. Since 2014, several major studies have demonstrated clinically significant results in quality of life scores1, mortality2, and long-term safety and efficacy1,3,4 for acute, massive (high risk) and submassive (intermediate-high risk) PE.

Today, more research is underway, both to confirm established clinical results (KNOCOUT Registry), as well as to address critical gaps in clinical evidence when comparing the clinical benefit of intervention with EKOS™ vs anticoagulation alone (Hi-PEITHO).

EKOS clinical results

  • EKOS brings 23-26% reduction to the RV/LV ratio – without an increase in bleeding1, 3, 4
  • It allows for lower lytic doses – up to 88-92% less than for standard systemic treatment – and shorter delivery duration of the thrombolytic agent5,1
  • It enables shorter average length of hospital stay (3.2 days) than for patients being treated with anticoagulation alone (6.7 days)6


The studies

HI-PEITHO, RCT ongoing, results expected in 2025

HI-PEITHO is a multi-center, prospective, randomised, controlled trial in the U.S.A and Europe. It compares the outcomes of ultrasound-facilitated, catheter-directed thrombolysis plus anticoagulation vs. anticoagulation alone for the treatment of acute, intermediate-high risk Pulmonary Embolism.
Scope: The randomised HI-PEITHO trial will enroll up to 406-544 patients with confirmed acute, intermediate-high risk PE at as many as 65 sites in the U.S. and Europe.
Purpose: The trial, which will follow patients for one year, will assess whether treatment with the EKOS system in combination with anticoagulation is associated with a significant reduction in adverse events compared to anticoagulation alone, within seven days of randomisation.
Endpoints: The composite primary endpoint is defined as PE-related mortality, cardiorespiratory decompensation or collapse and non-fatal symptomatic and objectively confirmed recurrence of PE.

View HI-PEITHO study details >

Principal investigators: Ken Rosenfield, MD and Stavros Konstantinides, MD, PhD, FESC, FRCP (Glasg)

REAL-PE, 2023

The REAL-PE Analysis is the largest real-world and near real-time dataset evaluating advanced therapies for PE patients. The results? Patients treated with the EKOS™ system had statistically significant lower rates of major bleeding and intracerebral haemorrhage than patients treated with Inari Medical’s FlowTriever™ system.

Learn more about the REAL-PE analysis > 


Results observed in the OPTALYSE trial are now being confirmed with the KNOCOUT PE registry, which presented 3-month data for the prospective cohort of 489 patients in 2021.
Scope: A prospective cohort of 489 patients across 83 international sites in the US and Europe.
Purpose: KNOCOUT was established to measure institutional adoption of a lower dose and lower-duration thrombolysis protocol for the EKOS system. It adds to the growing evidence that EKOS is effective at treating intermediate-high risk and high risk PE with lower lytic doses and shorter infusion durations compared to other thrombolytic therapies.
Get full details on the KNOCOUT PE registry >


Many participating physicians in the SEATTLE study saw patients improve in a matter of hours, which led them to ask: What would be the consequences if they stopped earlier than with the study’s 12hrs/24mg tPA treatment protocol? This led to the OPTALYSE trial.
Scope: Four groups of about 25 patients randomised to a specific time and dose. The shortest duration was 2 hours and 4mgs of tPA, while the longest was 6hrs and 24mgs. (To compare, the SEATTLE II study was at 12hrs/24mg tPA.)
Results: At 48hrs all groups improved significantly in RV/LV ratio1. Other cardiac parameters improved most in the 6hr/12mg group. Patients had follow-up until 1y; results were also published.
OPTALYSE also demonstrated a 23-26% decrease in the RV/LV ratio in 48 hrs3, as well as a bleeding rate of 3%.1
Learn more about the OPTALYSE trial and its bibliography >


The SEATTLE II trial, a larger single arm prospective study, consolidated the RV/LV results.
Scope: 150 patients.
Results: It showed a 25% decrease in RV/LV ratio over 48 hours via CTPA (pre/post CTPA)4.
More results from the SEATTLE II trial and its bibliography >

ULTIMA, 2014

The ULTIMA trial was the first randomised controlled trial (RCT) to examine ultrasound-accelerated thrombolysis vs anticoagulation.
Scope: 59 patients in Switzerland and Germany.
Results: The trial showed that a fixed-dose EKOS regimen was superior to anticoagulation alone in improving right ventricular dysfunction, with a 23% reduction in RV/LV ratio at 24 hours3 – without an increase in bleeding complications.
Read about the ULTIMA trial and its bibliography >

Discover our educational program on PE

Boston Scientific has developed an exclusive Pulmonary Embolism blended learning program with a team of well-known experts who are passionate about improving care for patients with PE.
Get an overview of this curriculum from the experts themselves.

1. TapsonVF, Sterling K, Jones N, et al. A randomized trial of the optimum duration of acoustic pulse thrombolysis procedure in acute intermediate-risk pulmonary embolism: the OPTALYSE PE trial. JACC Cardiovasc Interv. 2018;11:1401-1410. doi: 10.1016/j.jcin.2018.04.008
2. M. A. Mangi et al, Ultrasound-Assisted Catheter-Directed Thrombolysis of Acute Pulmonary Embolism: A Review of Current Literature, Cureus 9(7): e1492. DOI 10.7759
3. Nils Kucher, MD et al., Randomized, Controlled Trial of Ultrasound-Assisted Catheter-Directed Thrombolysis for Acute Intermediate-Risk Pulmonary Embolism Circulation 2014; 129: 479-486
4. G. Piazza MD, MS et al, A Prospective, Single-Arm, Multicentre Trial of Ultrasound-Facilitated, Low-Dose Fibrinolysis for Acute Massive and Submassive Pulmonary Embolism. The SEATTLE II Study, JACC Cardiovasc Interv. 2015 Aug 24; 8(10): 1382-92
5. Konstantinides S, Geibel A, Heusel G, et al. Heparin plus alteplase compared with heparin alone in patients with submassive pulmonary embolism. N Engl J Med. 2002;347:1143–1150.
6. Nykamp M et al., Safety and Efficacy of Ultrasound-Accelerated Catheter-Directed Lytic Therapy in Acute Pulmonary Embolism With and Without Haemodynamic Instability, J Vasc Surg: Venous and Lymphatic Disorders 2015: 3(5) 251-7

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