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NIHR play 'key role' in major international stroke study


A major international study has found that rapidly lowering blood pressure safely reduces the risk of bleeding in the brain in stroke patients being treated with clot-busting drugs.

The NIHR-supported research, was led in the UK by the University of Leicester and funded by the Stroke Association. The study, ‘Enhanced Control of Hypertension and Thrombolysis Stroke (ENCHANTED) is published in The Lancet.

Professor Tom Robinson, the study’s UK Chief Investigator and NIHR National Specialty Lead for Stroke, said: "The ENCHANTED study has shown that rapidly lowering blood pressure is a safe way to reduce the risk of bleeding in the brain for patients treated with clot busting drugs, though we need to understand better why this did not lead to overall improvements in recovery at three months following stroke.

"Research of this kind is essential if we're to ensure stroke treatments are safe for patients. NIHR played a key role in this important study, recruiting 961 participants across 31 sites in England. The study could well inform future clinical guidelines."

 Most strokes (85%) are ischaemic, which are caused by a blood clot blocking an artery leading to the brain. In this situation, doctors may inject a clot-busting medicine (a process known as thrombolysis) to break down and disperse the clot and restore blood flow. Thrombolysis reduces the brain damage caused by the stroke, especially when given as early as possible within the first four- and-a-half hours after the stroke occurs. However, it carries a small risk of serious bleeding to the brain.

The study investigated whether lowering a stroke patient’s systolic blood pressure (the top number in a blood pressure reading) to less than 140 millimetres of mercury (mm Hg) could safely reduce the risk of bleeding in the brain and lessen post-stroke disability better than lowering systolic blood pressure to the current recommended target of 180 mm Hg or less, for up to three days.

Researchers found that significantly fewer patients had bleeding in the brain after intensive compared to standard blood pressure management. Incidence of serious bleeds in the brain was also lower with intensive blood pressure reduction. Further, no harm was identified for intensive blood pressure management.

Crucially, the research teams also found that while there was no harm in intensively lowering blood pressure, neither did it significantly improve post-stroke recovery.

Professor Tom Robinson, said: "Bleeding in the brain can be a major side-effect of clot-busting stroke treatment. While more intensive blood pressure lowering is associated with reduced bleeding risk, there has been a longstanding belief that this additional treatment could worsen the stroke damage to the brain, causing higher levels of disability in patients over the longer term."

Hilary Reynolds, Executive Director for Strategy and Research at the Stroke Association said: "Findings from this research should provide reassurance that this approach to thrombolysis can be done safely. We’d like to see more research that leads to safer treatments and also people making better recoveries."

The study was led in the UK by the University of Leicester and was co-ordinated in the UK from the NIHR Leicester Biomedical Research Centre (BRC).  The study was led by a team at The George Institute for Global Health in Australia of more than 2,000 patients at 110 hospital sites in six countries, over several years.