The administration of medications to lower systolic blood pressure in acute ischaemic stroke patients who have undergone a successful mechanical thrombectomy procedure—also known as endovascular therapy (EVT)—”should be customised”, owing to possible safety concerns and only marginal benefits associated with their use. That is according to the findings of a Phase 2, late-breaking clinical trial presented at the 2023 International Stroke Conference (ISC; 8–10 February, Dallas, USA).
“Healthcare professionals should be cautious when lowering blood pressure after endovascular treatment, as there are some signs that blood pressure that is too low may be harmful,” said lead study author Eva Mistry (University of Cincinnati, Cincinnati, USA), who delivered data from the BEST II trial at ISC 2023. “Individual patients might require lowering of blood pressure due to medical and neurological reasons—however, it should not be done as blanket practice with all patients. It may benefit some patients and needs to be customised.”
Previous research has indicated that higher systolic blood pressure after EVT is associated with greater disability in people who have had an acute ischaemic stroke, and a systolic blood pressure of 140–160mmHg has been associated with better outcomes following the procedure. But, whether using blood pressure medications to artificially lower systolic blood pressure to less than 180mmHg is safe and effective has not been demonstrated following clot removal, according to the BEST II researchers.
“There is always the concern if blood pressure is lowered too much in patients who are having an acute ischaemic stroke that it could make the size of their stroke worse by reducing already compromised blood flow in that area,” Mistry explained. “Endovascular therapy has changed the landscape in acute stroke treatment. Patients do drastically better when they receive endovascular treatment, compared to when they do not. And, despite the enormous effectiveness of endovascular treatment, about 50% of patients remain disabled or die at 90 days, so we are on a quest to understand if there are additional strategies that may further improve outcomes in these patients.”
In the prospective, randomised BEST II trial, researchers hypothesised that patients allocated to lowering systolic blood pressure targets might have a higher volume of stroke size at 36 hours and increased disability at 90 days. They enrolled 120 patients (average age of 70 years, 57% female) who had an acute ischaemic stroke and underwent successful EVT at one of three urban comprehensive stroke centres in the USA between January 2020 and February 2022.
Forty patients were randomly assigned to have their systolic blood pressure lowered to a target of ≤180mmHg; 40 patients were assigned to a systolic blood pressure target of <160mmHg; and another 40 patients were targeted to reach a systolic blood pressure of <140mmHg. Patients were treated with an anti-hypertensive medication called nicardipine, administered intravenously, started within one hour after EVT and given for 24 hours if their systolic blood pressure was above the target they were assigned.
The BEST II researchers wanted to assess whether lowering blood pressure may cause harm to brain tissue—which is particularly vulnerable during the 24 hours after a stroke—and to assess disability 90 days later.
In the ≤180mmHg-, <160mmHg- and <140mmHg-target groups, average systolic blood pressure reached 129mmHg, 130mmHg, and 123mmHg, respectively. In addition, the average 36-hour stroke volumes showed no conclusive evidence of harm, and 90-day disability outcomes indicated only a slight indication of harm.
“The main outcomes of the study were the size of stroke at 36 hours and degree of disability at 90 days,” Mistry said. “Although the study did not find significant evidence of an unequivocal harm of lower blood pressure targets in this population in terms of worsening size of stroke or increasing disability, the trends indicated that there may only be marginal benefit on patients’ long-term disability by lowering blood pressure after endovascular treatment. In fact, there was an indication that lowering the blood pressure after thrombectomy may worsen patients’ long-term disability.
“This study provides an indication that patients’ blood pressure should be allowed to be autoregulated after endovascular treatment, unless about 180mmHg, and clinicians might want to be cautious when they reflexively lower the blood pressure, since there may be some signal of harm. There should be individual patient decision-making, such as if there are other medical reasons for lowering the blood pressure or if there are signs of significant bleeding in the brain.”
BEST II study limitations cited by the researchers include the small number of patients involved as well as the trial being conducted at just three US centres, potentially limiting the generalisability of the results to stroke patients being treated elsewhere.
In her ISC presentation, Mistry posited that “we cannot rule out the potential for harm” with blood pressure-lowering medications, advocating an individualised approach to their use after EVT, before concluding that ongoing trials—OPTIMAL BP, CRISIS I and HOPE—will provide additional insight on this topic.