Ultrasound-guided catheter clot-dissolving treatment for adults with moderate-to-high risk pulmonary embolism

ULTRAsound-assisted Catheter-guided Thrombolysis for Intermediate-high Risk Patients With Pulmonary Embolism

This trial will try ultrasound-guided catheter thrombolysis (EKOS) to see if it is safe and helps adults with intermediate-high or high-risk pulmonary embolism.

Quick facts

• Phase: Not applicable
• Study type: Interventional
• Enrollment: 300 (estimated)
• Ages: 18 Years and up
• Sex: All
• Sponsor: National Medical Research Center for Cardiology, Ministry of Health of Russian Federation (Government)
• Locations: 1 site (Moscow)
• Trial ID: NCT07452991 on ClinicalTrials.gov

What this trial studies

This prospective study will enroll adults with intermediate-high or high-risk acute pulmonary embolism and deliver ultrasound-assisted, catheter-directed thrombolysis using the EkoSonic Endovascular System (EKOS). The procedure uses targeted, lower-dose thrombolytic infusions directly into the pulmonary arteries with ultrasound to promote clot breakdown. The primary outcome is all-cause mortality through 360 days of follow-up, and secondary outcomes include changes in echocardiographic measures such as the RV/LV diameter ratio. The study will provide controlled data on safety and clinical outcomes for catheter-directed thrombolysis in this patient group.

Who should consider this trial

Good fit: Adults (≥18) with objectively confirmed acute PE who have right ventricular dysfunction and elevated cardiac biomarkers consistent with intermediate-high risk and who can undergo catheter-directed therapy are ideal candidates.

Not a fit: Patients with low-risk PE, active bleeding or other contraindications to thrombolysis, or those needing immediate systemic thrombolysis or surgical intervention are unlikely to benefit from this procedure.

Why it matters

Potential benefit: If successful, this approach could reduce deaths and long-term right-heart strain while lowering bleeding risk by delivering smaller, targeted doses of clot-dissolving drugs.

How similar studies have performed: Previous trials of EKOS and other catheter-directed thrombolysis (such as ULTIMA, SEATTLE II, and OPTALYSE) have shown improvements in RV/LV ratio and RV function with lower drug doses, though clear mortality benefits remain unproven.

Eligibility criteria

Inclusion Criteria:

* Adults aged ≥ 18 years at time of enrollment;
* Ability to provide written informed consent (or legally authorized representative consent where applicable);
* Objectively confirmed acute pulmonary embolism (PE) by contrast-enhanced computed tomography pulmonary angiography (CTPA) demonstrating intraluminal filling defects in at least one segmental, lobar, or more proximal pulmonary artery;
* Hemodynamically stable at presentation (i.e., not meeting high-risk PE criteria of sustained hypotension, shock, or need for vasopressor support per ESC 2019 and AHA/ACC risk stratification);
* Evidence of right ventricular (RV) dysfunction on imaging (e.g., RV/LV ratio \> 1.0 on CTPA or echocardiography);
* Elevated cardiac biomarkers, including troponin I or T above the upper limit of normal;
* Intermediate-high risk features defined as the combination of imaging RV dysfunction and positive cardiac biomarkers, consistent with ESC stratification;
* At least one clinical indicator of elevated early risk such as:

  1. Tachycardia (e.g., HR ≥ 100 bpm),
  2. Mild systolic blood pressure reduction (e.g., SBP ≤ 110 mmHg but not meeting high-risk thresholds),
  3. Hypoxemia (SpO₂ \< 90% on room air).

Exclusion Criteria:

* Presence of hemodynamic instability, defined as at least one of the following:

  1. Systolic blood pressure (SBP) \< 90 mmHg or a drop ≥ 40 mmHg from baseline for \> 15 minutes not attributable to arrhythmia, hypovolemia, or sepsis,
  2. Requirement for vasopressors to maintain SBP ≥ 90 mmHg,
  3. Cardiogenic shock, defined by clinical signs of end-organ hypoperfusion (e.g., altered mental status, oliguria, lactate elevation),
  4. Need for ECMO or other mechanical circulatory support initiated prior to assessment,
  5. Cardiac arrest requiring resuscitation.
* Active major bleeding or conditions with high bleeding risk (e.g., known intracranial pathology predisposed to hemorrhage or associated with ongoing pharmacotherapy);
* Recent (\< 3 months) intracranial or intraspinal surgery, major trauma, or stroke;
* Known central nervous system neoplasm or metastatic cancer with high bleed risk.
* Administration of systemic thrombolytic agents or catheter-directed thrombolysis prior to registry assessment for the index PE episode;
* Known hypersensitivity to alteplase, unfractionated heparin (UFH), or any of their excipients.
* Requirement for intensive care admission for conditions unrelated to the index PE;
* Duration of symptoms attributable to the index PE \> 14 days at presentation, as defined in contemporary trial criteria;
* Known severe thrombocytopenia (e.g., platelet count \< 100 × 10⁹/L) or coagulopathy precluding safe catheter access;
* Life expectancy \< 6 months due to advanced comorbid disease unrelated to acute PE;
* Pregnancy.

Where this trial is running

Moscow

• National Medical Research Center for Cardiology named after academician Yevgeniy Chazov of the Ministry of Health of the Russian Federation — Moscow, Russia (Recruiting)

Study contacts

• Principal investigator: Dmitry Pevzner, MD, D.Sc. — National Medical Research Center for Cardiology named after academician Yevgeniy Chazov of the Ministry of Health of the Russian Federation
• Study coordinator: Oleg Dorogun, MD

Conditions Pulmonary Embolism; Pulmonary embolism; Ultrasound-assisted Catheter-guided Thrombolysis