Stopping the damage caused by stroke

Strokes cause around 35,000 deaths a year in the UK alone, and are the single biggest cause of severe disability. A stroke happens when the blood supply to part of the brain is disrupted, causing brain cells to become damaged or die. This usually occurs as a result of a blockage in one of the brain’s blood vessels, called an ischaemic stroke; or when a blood vessel bursts, causing a bleed in the brain called a haemorrhagic stroke.

The very first research project funded by the BHF in the 1960s was to support BHF fellow    Dr Enid Joan Acheson at North Staffordshire Royal Infirmary in Stoke-on-Trent to identify the causes of strokes, conditions that were very poorly understood back then. Since then, we have funded more research to better prevent and treat these life-threatening conditions.

Taking statins to reduce the risk of ischaemic stroke

In the 1970s, it became clear that high level of cholesterol was associated with an increased risk of having a stroke.

A large clinical trial, called WOSCOPS, led by BHF Professor Stuart Cobbe and colleagues in Glasgow in the 1990s showed that people with high cholesterol taking cholesterol-lowering statins had a lower risk of having a stroke. The team followed up the same group of people after 10 and 15 years and showed in 2007 that the benefit of taking statins appeared to extend to at least 10 years after the original trial.

In the 2000s, BHF Professor Rory Collins in Oxford led the BHF/MRC Heart Protection Study to test if statins could also help people with ‘normal’ cholesterol levels. The results published in 2004 showed that statins reduced the risk of having an ischaemic stroke by a third in this group of people.

Improving outcomes after ischaemic stroke

Giving a “clot-busting” drug to break down the clot and restore blood flow through the brain in the first few hours after an ischaemic stroke can greatly improve the chances of recovery. Right now, doctors use a drug called alteplase, but newer clot-busting drugs are used in other fields of medicine. One of these is a drug called tenecteplase.

We are funding several clinical trials looking at how tenecteplase might help treat strokes. Professor Keith Muir at the University of Glasgow is leading the ATTEST-2 trial to compare tenecteplase with alteplase in thousands of people with an ischaemic stroke, to see which is best at helping patients recover. Because tenecteplase is less expensive and easier to give than alteplase, it could be a cheaper and more straightforward way to improve the outlook for stroke patients.

Improving outcomes in mini-stroke

Some strokes cause mild symptoms or appear to improve quickly. However, despite seeming mild these mild strokes – also known as transient ischaemic attacks or mini-strokes – can lead to long-lasting disability.

Professor Muir is also investigating whether tenecteplase could help doctors stop mini-strokes from causing disability. People who’ve had a mini-stroke are not usually offered clot-busting drugs because their symptoms may be considered too mild or they are judged to be rapidly improving. Also, clot-busting drugs can cause bleeding on the brain, so doctors are careful to give them only when it’s clear that they could help. Professor Muir and his team have received BHF funding to take part in the TEMPO-2 trial, an international clinical trial testing whether tenecteplase improves recovery in people with mini-stroke compared with usual treatments, such as aspirin. The study could lead to a new way to treat this kind of stroke.

Wake-up stroke

Clot-busting drugs have to be given within hours of the stroke happening. But about one in five strokes occur when someone is asleep and then wakes up with symptoms. People who have ‘wake-up strokes’ are not offered clot-busting treatment because it’s not known what time the stroke happened and whether the treatment would work.

We’ve funded Professor Thompson Robinson, at the University of Leicester, to take part in the TWIST clinical trial. This is comparing tenecteplase with usual care (no clot-busting treatment) in people who present with wake-up stroke to see if tenecteplase helps improves recovery in this patient group.

Haemorrhagic stroke

What about strokes that are caused by a bleed into the brain?

We funded Professor Rustam Salman and his team at the University of Edinburgh to explore a controversial issue: whether doctors should avoid antiplatelet drugs (drugs like aspirin and clopidogrel, that reduce the chances of a heart attack) after a brain bleed. Many people who have a brain bleed are already prescribed aspirin, often because they have coronary heart disease. Aspirin is a blood thinner, which reduces the chance of clots forming that could cause a heart attack or ischaemic stroke. But if someone has just had a bleed in the brain, it’s important for their blood to be able to clot so that the bleeding stops. So the guidance is to stop taking aspirin immediately so that a haemorrhagic stroke doesn’t worsen. But no-one knew whether these patients should then restart their aspirin.

The results of the BHF-funded RESTART study published in 2019 suggested it is safe for people who have had a stroke caused by bleeding in the brain to restart blood-thinning drugs without raising their risk of another brain bleed. In fact, the results suggested that these drugs might even reduce the risk of a further brain bleed. The BHF is currently funding further research to confirm whether this is indeed the case. The findings could have major implications for the treatment and management of people who’ve suffered an haemorrhagic stroke.

First published 1st June 2021