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Study of Catheter-Directed Thrombolysis Using Alteplase for Treatment of Intermediate-High Risk Acute Pulmonary Embolism

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study focuses on patients with intermediate-high risk acute pulmonary embolism, a serious condition where blood clots block arteries in the lungs. The study compares two different treatment approaches: catheter-directed thrombolysis using Actilyse (also known as alteplase) versus standard blood-thinning therapy. Catheter-directed thrombolysis is a procedure where clot-dissolving medication is delivered directly to the blood clot through a thin tube.

The purpose of the study is to determine if catheter-directed thrombolysis leads to better outcomes compared to standard treatment in terms of survival, prevention of new blood clots, and overall heart and lung function. The medication Actilyse will be given through an infusion directly to the blood clot, with a maximum daily dose of 20 milligrams over the course of one day.

During the study, patients will undergo various tests to monitor their heart and lung function, including computed tomography angiography to look at blood vessels in the lungs, and heart ultrasound tests to check heart function. Patients will be followed for up to two years to assess their recovery and quality of life after treatment.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial diagnosis confirmation

    Your participation begins after a computed tomography angiography (CTA) confirms blood clots in your lungs, known as pulmonary embolism (PE)

    The condition must be diagnosed within 14 days of first symptoms

  2. Step 2

    Medical assessment

    Medical team will evaluate your heart function using special tests

    Blood tests will be performed to check specific markers related to heart strain

    Your overall health risk will be assessed using a special scoring system

  3. Step 3

    Treatment assignment

    You will be randomly assigned to receive either:

    Standard blood-thinning medication treatment, or

    Catheter-directed thrombolysis (CDT) - a procedure where medication is delivered directly to the blood clot through a thin tube

  4. Step 4

    Follow-up evaluations

    Initial assessment after 24 hours

    Health status check at 7 days

    Follow-up visit at 30 days

    Additional check-ups at 12 months

    Final evaluation at 24 months

  5. Step 5

    Testing during follow-up

    Heart ultrasound examinations to measure heart function

    Physical ability tests including a 6-minute walk test

    Quality of life assessments using questionnaires

    Regular monitoring for any health changes or complications

Who can join the trial?

7 criteria

  • Must be between 18 and 80 years old
  • Must have a pulmonary embolism (blood clot in the lung) confirmed by CT scan within the last 14 days from when symptoms started
  • Must have an intermediate-high risk pulmonary embolism with:
    • A positive sPESI score (a measure of disease severity)
    • Right ventricle dysfunction (decreased function of the heart's right chamber)
    • Elevated levels of certain blood proteins (hs-troponin or NT-proBNP) that indicate heart stress
    • Must be able to understand and sign the informed consent form
    • Both men and women can participate

Who cannot join the trial?

15 criteria

  • Age below 18 years or above 75 years
  • Active bleeding or high risk of bleeding
  • Recent major surgery within the last 14 days
  • History of stroke (a condition where blood flow to the brain is disrupted) in the past 6 months
  • Severe thrombocytopenia (very low blood platelet count below 50,000)
  • Pregnancy or breastfeeding
  • Life expectancy less than 30 days
  • Severe kidney failure requiring dialysis
  • Known bleeding disorders
  • Inability to take blood thinning medications
  • Severe uncontrolled hypertension (high blood pressure)
  • Active cancer requiring treatment
  • Previous participation in this clinical trial
  • Unable to provide informed consent
  • Severe liver disease
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Investigated drugs

Based on the provided trial information about treating pulmonary embolism, the key treatments involved are: Thrombolytic medication is administered through a catheter directly into the blood clot in the pulmonary artery. This medication helps to break down blood clots that are blocking blood flow to the lungs. This targeted approach allows the clot-dissolving medication to work directly at the site of the blockage. Standard anticoagulants are blood-thinning medications that help prevent existing blood clots from getting bigger and stop new clots from forming. These medications are the conventional treatment for pulmonary embolism and work throughout the entire bloodstream to prevent clotting.

What is already known about the treatment

  • Thrombolytic Agents

    These are medications administered through a catheter directly into blood clots in the pulmonary arteries to treat acute pulmonary embolism. The drugs work by breaking down blood clots through enzymatic action, converting plasminogen to plasmin which then dissolves fibrin in the clots. Currently, catheter-directed thrombolysis (CDT) is being studied as an alternative to standard anticoagulation therapy for patients with intermediate-high risk pulmonary embolism, with the aim of reducing mortality and preventing complications. These medications belong to the fibrinolytic drug class and are typically used in emergency medicine settings under careful medical supervision.

  • Anticoagulants

    These are blood-thinning medications used as the standard treatment for acute pulmonary embolism, administered either orally or through injection. They work by interfering with the blood clotting cascade, preventing the formation of new clots and stopping existing clots from growing larger. Anticoagulants are well-established in medical practice and serve as the conventional therapy for preventing the progression and recurrence of pulmonary embolism. These medications belong to several classes including heparins, vitamin K antagonists, and direct oral anticoagulants, with their use carefully monitored to balance effectiveness and bleeding risk.

Investigated diseases

  • Pulmonary Embolism (PE)

    A condition where one or more blood clots block arteries in the lungs. The clot typically forms in a deep vein of the leg and travels through the bloodstream to the lungs. This blockage affects blood flow and decreases oxygen levels in the blood. PE can cause shortness of breath, chest pain, and rapid heartbeat. The severity can range from small clots with minimal symptoms to larger ones affecting significant portions of the lungs.

  • Chronic Thromboembolic Pulmonary Hypertension (CTEPH)

    A rare form of high blood pressure affecting the lungs and heart. It develops when old blood clots in lung arteries become hardened scar tissue, permanently blocking or narrowing these vessels. This condition leads to increased pressure in the pulmonary arteries and causes the heart to work harder. Symptoms typically include breathlessness during physical activity, fatigue, and chest discomfort.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-516144-25-00Protocol codePRAGUE-26Estimated enrolment558 patientsSponsorFakultni Nemocnice Kralovske Vinohrady

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