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Comparing two heparin sodium doses on silent brain lesions in patients undergoing embolization of unruptured intracranial aneurysm with drug combination

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What is this trial about?

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

People with an intracranial aneurysm have a small bulge in a blood vessel inside the brain that can be treated by threading a thin tube through the arteries and placing tiny coils to block the bulge. During this procedure a medication called heparin is given through an IV to keep blood from clotting, and the study compares a lower dose (30 IU per kilogram of body weight) with a higher dose (70 IU per kilogram). In addition, a short‑acting drug called protamine sulfate may be used at the end of the procedure to neutralize the heparin, while patients also receive standard blood‑thinning medicines such as acetylsalicylic acid (aspirin) and ticagrelor to further reduce clot risk.

The purpose of the study is to find out which heparin dose best prevents tiny areas of reduced blood flow in the brain that are not felt as symptoms but can be seen on a brain scan called diffusion-weighted imaging (a type of MRI) performed about a day after the procedure. Participants are randomly assigned to one of the two dose groups, receive the medication during the embolization, stay in the hospital for monitoring, and have a brain scan 24 ± 12 hours later to check for these silent lesions, as well as to watch for any bleeding or stroke that might occur shortly after the treatment.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline assessment

    After enrollment, you will have a brief medical review that includes confirming the diagnosis of an intracranial aneurysm and checking any current medications.

    A blood sample may be taken to determine your weight, which is needed to calculate the correct dose of the study medication.

  2. Step 2

    Pre‑procedure medication

    You will receive acetylsalicylic acid (commonly known as aspirin) 250 mg given by intravenous injection. this dose is given once before the procedure to help prevent clot formation.

    You will also take ticagrelor 180 mg by mouth once before the procedure. ticagrelor is an antiplatelet medicine that works together with aspirin to reduce the risk of clots.

  3. Step 3

    Heparin administration during the procedure

    During the embolization, you will receive an intravenous bolus of heparin. the dose is based on your weight and will be either 30 international units (iu) per kilogram or 70 iu per kilogram, as assigned by the study protocol.

    The heparin is given as a single injection directly into a vein at the start of the endovascular treatment.

  4. Step 4

    Possible reversal of heparin

    After the embolization, the medical team may give protamine sulfate 70 units by injection to neutralize the effect of heparin. this step is performed only if it is needed according to the procedure outcome.

  5. Step 5

    Post‑procedure monitoring

    You will remain in the hospital for at least 24 hours after the procedure. during this time, vital signs, neurological status, and any signs of bleeding or clotting will be checked regularly.

    If any symptoms of stroke or bleeding appear, additional examinations will be performed.

  6. Step 6

    Brain mri with dwi

    Within 24 ± 12 hours after the embolization, a brain magnetic resonance imaging (mri) scan with diffusion‑weighted imaging (dwi) will be performed. this scan looks for tiny areas of recent ischemia (restricted blood flow) that may not cause symptoms.

  7. Step 7

    Neurological evaluation and discharge

    After the MRI, a brief neurological exam will be done, including the national institutes of health stroke scale (nihss) score, which measures any stroke‑related deficits.

    If no serious complications are identified, you will be discharged home with instructions for routine follow‑up.

Who can join the trial?

6 criteria

  • You must be at least 18 years old.
  • You must have a saccular intracranial aneurysm (a balloon‑like bulge in a brain blood vessel) that is either unruptured (has not burst) or, if it has burst, it happened more than 30 days ago.
  • You must have no neurological deficit (no weakness, numbness, speech problems, or other loss of brain function).
  • Your score on the modified Rankin Scale (mRS) before the procedure must be less than 3, which means you have only slight or no disability.
  • You must give free and informed consent, meaning you understand the study and agree to join voluntarily.
  • You must be covered by a social security scheme or similar health‑insurance program.

Who cannot join the trial?

27 criteria

  • Current anticoagulant treatment (blood‑thinning medicines such as Vitamin K antagonists, oral anticoagulants, or full‑dose heparin) at the time of the aneurysm procedure.
  • Known bleeding disorder (any condition that makes blood clot poorly, called a coagulopathy).
  • Pregnancy or breastfeeding.
  • Planned treatment of several aneurysms in different arteries during the same procedure (treating more than one aneurysm in the same artery is allowed).
  • Obesity defined as a body‑mass index (BMI) greater than 30.
  • Inadequate understanding of French to follow study instructions.
  • Legal protection such as guardianship or curatorship.
  • Unable to give personal consent for participation.
  • Deprived of liberty by a court or administrative decision.
  • Other planned endovascular procedures in the neck or brain at the same time (for example, carotid stenting or treatment of an arteriovenous fistula or malformation).
  • Very difficult blood‑vessel access due to severe narrowing (atherosclerosis), extreme twisting (tortuosity), or damage from a previous artery tear (dissection).
  • Carotid artery stent placed within the past 3 months on the same side as the aneurysm.
  • Recent ischemic brain event (stroke or transient ischemic attack) within the last month.
  • Recent surgery with bleeding risk performed within the past 30 days.
  • Brain bleeding (intracranial or subarachnoid hemorrhage) within the past 30 days.
  • Cerebral amyloid angiopathy (a condition where abnormal protein deposits make brain vessels fragile) suspected or known.
  • Aneurysm linked to a cerebral arteriovenous malformation (AVM) (an abnormal tangle of blood vessels in the brain).
  • Organic lesions that increase bleeding risk in the brain.
  • End‑stage kidney disease or severe liver failure.
  • Contraindication to unfractionated heparin (a reason why this type of heparin cannot be used).
  • Severe allergy to contrast dye used in imaging studies.
  • Allergy to nickel, titanium, or their alloys (metals often found in medical devices).
  • Participating in another clinical study that could affect the results.
  • Contraindication to MRI or angiography (any reason why these imaging tests cannot be performed).
  • Other serious health problems that could affect brain assessments or survival, such as major stroke effects, severe head injury, advanced neurodegenerative diseases (e.g., Parkinson’s disease, ALS), dementia, active brain tumor, multiple sclerosis, uncontrolled epilepsy, severe psychiatric illness, major cancer, or serious infections.
  • Allergy to heparin, aspirin (ASA), or other blood‑platelet medicines.
  • History of heparin‑induced thrombocytopenia (a condition where heparin causes a dangerous drop in platelets).
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Investigated drugs

  • Heparin

    is a medication given through an IV line during the aneurysm embolization procedure. It helps prevent blood clots from forming while the doctors are working inside the blood vessels, which can reduce the risk of stroke or other complications.

  • Protamine sulfate

    is used after the procedure to neutralize the effect of heparin. By reversing heparin’s action, it helps the blood’s normal clotting ability return to normal, lowering the chance of bleeding problems once the procedure is finished.

  • Aspirin

    (acetylsalicylic acid) is an oral medication taken before the procedure to thin the blood slightly. It works by preventing platelets from clumping together, which further reduces the risk of clot formation during and after the treatment.

  • Ticagrelor

    is another oral antiplatelet drug given before the embolization. It blocks a different pathway that platelets use to stick together, providing added protection against clots during the endovascular treatment.

What is already known about the treatment

  • Heparin Sodium

    This medication is given as a clear liquid that is injected directly into a vein, either as a quick push or a slow drip. It is an approved and widely used blood thinner that helps prevent clots during procedures like aneurysm repair. It works by attaching to a natural protein in the blood called antithrombin, which then disables several clot‑forming factors. It belongs to the antithrombotic (heparin) class of drugs.

  • Protamine Sulfate

    Protamine is administered by injection to quickly neutralize the effects of heparin after a medical procedure. It is an approved drug commonly used in surgeries and cardiac interventions to reverse heparin’s action. The positively charged protamine molecules bind to the negatively charged heparin, forming a stable complex that stops heparin from thinning the blood. It is classified as a heparin antagonist.

  • Acetylsalicylic Acid

    This drug can be given by injection into a vein and is used to reduce the risk of blood clots. It is an over‑the‑counter medication that is also prescribed to protect the brain and heart after certain procedures. It works by blocking an enzyme called COX, which lowers the production of substances that make platelets stick together. It is part of the antiplatelet and non‑steroidal anti‑inflammatory drug (NSAID) groups.

  • Ticagrelor

    Ticagrelor is taken by mouth as a tablet and is used to keep platelets from forming clots, especially after heart or brain vessel procedures. It is a prescription medication approved for preventing clot‑related events. The drug blocks a specific receptor (P2Y12) on platelets, which stops them from becoming sticky. It belongs to the class of P2Y12 receptor inhibitors, a type of antiplatelet agent.

Investigated diseases

Saccular intracranial aneurysm - A localized bulge in a cerebral artery wall that forms a sac‑shaped dilation. Over time the aneurysm may enlarge as the vessel wall weakens. It can press on nearby brain tissue, causing headaches or neurological signs. If the wall becomes thin, the aneurysm may rupture, leading to bleeding into the surrounding space. Even when unruptured, the aneurysm can alter blood flow and increase the risk of small clot formation that may appear as ischemic lesions on imaging.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2026-526530-13-00Estimated enrolment124 patientsSponsorCentre Hospitalier Universitaire De Bordeaux

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