The safety and potential benefit of a strategy to more intensively control blood pressure in patients who receive 'clot-busting' treatment for acute ischaemic stroke has been demonstrated in a clinical trial led by The George Institute for Global Health.
Researchers found stroke patients who received intensive blood pressure lowering were significantly less likely to suffer bleeds on the brain, a side-effect associated with people being treated with clot-busting therapies known as thrombolysis.
The study, which involved over 2000 patients from 110 hospitals in 15 countries from 2013 to 2018, has resolved much of the controversy surrounding the role of intensive blood pressure lowering in this critical condition in showing the treatment is safe and reduces the risk of major bleeding in the brain, which is the major potential side-effect of clot-busting treatments.
Researchers investigated whether intensive lowering systolic blood pressure (the top number in a blood pressure reading) to less than 140 millimeters of mercury (mm Hg) could reduce post-stroke disability and safely reduce the risk of bleeding in the brain better than lowering systolic blood pressure to the standard recommended target of less than 180 mm Hg over three days.
The findings were simultaneously presented at the International Stroke Conference of the American Heart Association (AHA) / American Stroke Association (ASA) and published in The Lancet.
Most strokes are ischaemic and occur due to sudden blockage of a blood vessel in the brain. The clot-busting drug, alteplase (or tPA), and/or insertion of tiny mechanical device into the blood vessel, often referred to as 'reperfusion therapy' to remove clot-causing blockage, are proven treatments for acute ischaemic stroke.
Despite these treatments having small risks of serious bleeding, they have been shown to reduce the brain damage caused by ischaemic stroke, provided they are given early after the onset of symptoms in carefully selected patients.
Lead investigator of the study, Professor Craig Anderson, Executive Director of The George Institute, China said: "There has been much debate over whether any benefits are offset by potential harms of intensive blood pressure lowering early after the onset of acute ischaemic stroke.
"This study now clearly shows more intensive blood pressure control than is currently recommended has the potential to make thrombolysis treatment safer, by reducing the risk of serious bleeding in the brain."
- The level of disability at 90 days did not differ between groups of patients allocated to intensive and standard blood pressure management;
- Significantly fewer patients had bleeding within the brain after intensive compared to standard blood pressure management;
- Large and serious bleeding in the brain were lower with intensive blood pressure lowering;
- There were no harms identified for intensive blood pressure lowering;
- Results were influenced by the difference in blood pressure between the patient groups being less than planned, with many patients in the standard treatment group receiving more blood pressure lowering than typically used in clinical practice;
- More research is required to better understand why the reduced risk of bleeding in the brain did not translate into improved overall outcome for patients.
"These findings also highlight the need for more research to better understand the underlying mechanisms of benefit and harm of early intensive blood pressure lowering in the patients receiving modern reperfusion therapy with thrombolysis and devices, given that the reduction in brain haemorrhage failed to translate into improvements in overall recovery for patients," added Professor Tom Robinson, Co-Lead Investigator and Head of the Cardiovascular Research Centre at the University of Leicester, UK.
Stroke accounts for almost 5% of lives lost due to premature death or disability, and 10% of all deaths worldwide.
It is estimated that on average, one in four people will suffer a stroke across the world, but it is as high a one in three in many parts of Asia and Eastern Europe.
In China, where most of the study participants were from, stroke is the leading cause of death and disability.
The National Health and Medical Research Council (NHMRC) of Australia and the UK Stroke Association were the main funders of the study.
- World Stroke Organization
- Global, regional, and country-specific lifetime risks of stroke, 1990 and 2016. Global Burden of Disease authors. New England Journal of Medicine 2018
- 2018 China Ischaemic Stroke Guideline