Project summary
Extending the time for thrombolysis in emergency neurological deficits with tenecteplase (EXTEND TNK 24)
What is the issue for NSW?
Ischaemic stroke is caused by blockage of an artery supplying a portion of the brain. In most cases, this blockage is caused by a blood clot. Successful treatment of stroke depends on removal of this blood clot, which can be accomplished mechanically with a catheter inserted into the brain artery, or using a drug commonly known as a ‘clot buster’, which can be injected into a vein in the arm.
Although catheter-based therapy has been shown to be effective up to 24 hours after onset in carefully selected patients, clot busters are approved for use only within 4.5 hours of onset. Unfortunately, many patients present with blood clots that are in small arteries that cannot be reached with a catheter. If these patients present more than 4.5 hours after their stroke began, they cannot be treated at all.
We plan to use the same selection techniques that were used to prove catheter- based treatment can be effective for up to 24 hours after onset to select patients for clot buster therapy.
What does the research aim to do and how?
Clot busters can be used in many more hospitals than catheter-based methods, which require specialised equipment and personnel to perform the operation. This means we can treat many more patients living in rural and small urban centres far from specialised hospitals found in only two cities in NSW.
We will use an advanced form of brain imaging, known as ‘CT Perfusion’. This allows us to measure the blood flow to different parts of the brain. Brain blood flow measurements can be used to predict who will respond to therapy, even when they present late (more than 4.5 hours after onset) and who will not. We will use CT Perfusion to select patients for treatment. They will be randomly (like the flip of a coin) assigned to receive a clot buster known as tenecteplase (‘TNK’) or the standard treatment, which is a baby aspirin. We will then re-image the patients at 24 hours and measure their clinical symptoms for the next three months.
We believe that patients treated with TNK will have better outcomes than those given aspirin. Our research will be the first to show that clot busters can be used safely and effectively in patients presenting to hospital more than 4.5 hours after onset. This will allow treatment of a group of stroke patients who currently have no options available to them, including many who live in rural areas. This study has the potential to change guidelines and treatment approaches almost immediately.