BASEL, SWITZERLAND — Early reduction of blood pressure has a beneficial effect in hemorrhagic stroke but a detrimental effect in ischemic stroke, new trial data show. The findings could shake up recommendations on control of blood pressure in acute stroke patients.
“This is the first time that we have randomized evidence of blood pressure control prior to reperfusion in ischemic stroke patients, and our data will challenge the current guidelines that recommend lowering blood pressure to below 180 mm Hg systolic in these patients,” said study coauthor Craig Anderson, MD, George Institute for Global Health, Sydney, Australia.
“And this study also clearly shows for the first time that getting blood pressure under control in hemorrhagic stroke patients in the first couple of hours has definitive benefits,” he added.
The findings were presented on May 16 at the European Stroke Organization Conference (ESOC) annual meeting and published online simultaneously in The New England Journal of Medicine.
A Test of Early BP Control
The trial was conducted to test the strategy of very early blood pressure control during patient transport in an ambulance after acute stroke, which investigators suspected could benefit patients with both types of stroke.
The hypothesis was that this would reduce bleeding in the brain for those with hemorrhagic stroke. For ischemic stroke patients, it was thought this strategy would speed up administration of thrombolysis, because guidelines recommend bringing blood pressure under control before thrombolysis.
For the INTERACT4 trial, which was conducted in China, 2404 patients with suspected acute stroke and elevated systolic blood pressure (≥ 150 mm Hg) who were assessed in the ambulance within 2 hours after symptom onset were randomized to receive immediate treatment with intravenous urapidil to lower the systolic blood pressure or usual blood pressure management (usual care group).
The median time between symptom onset and randomization was 61 minutes, and the mean blood pressure at randomization was 178/98 mm Hg.
Stroke was subsequently confirmed by imaging in 2240 patients, of whom 46% had a hemorrhagic stroke and 54% an ischemic stroke.
At the time of arrival at the hospital, the mean systolic blood pressure in the intervention group was 158 mm Hg, compared with 170 mm Hg in the usual care group.
The primary efficacy outcome was functional status as assessed by modified Rankin scale score at 90 days.
Overall, there was no difference between the two groups in terms of functional outcome scores (common odds ratio [OR], 1.00; 95% CI, 0.87-1.15), and the incidence of serious adverse events was similar.
But the study showed very different results in patients with hemorrhagic stroke vs those with ischemic stroke.
‘Slam-Dunk’ Effect
Anderson has led several previous trials of blood pressure control in stroke patients, some of which have suggested benefit of lowering blood pressure in those with hemorrhagic stroke, but he says the results of the current trial are more clear-cut.