BEST II Evaluates Safety of Lowering Blood Pressure After Mechanical Thrombectomy

February 10, 2023—The American Stroke Association (ASA) announced findings from a clinical trial that suggest using medications to lower systolic blood pressure may not be safe or effective among patients who have an acute ischemic stroke and undergo successful endovascular mechanical thrombectomy.

The phase 2 BEST II study findings were presented as a late-breaking clinical trial at ASA’s International Stroke Conference 2023 held February 8-10 in Dallas, Texas, and virtually.

Lead investigator Eva Mistry, MBBS, is a stroke neurologist and Assistant Professor in the Department of Neurology and Rehabilitation Medicine at the University of Cincinnati in Cincinnati, Ohio.

“Health care professionals should be cautious when lowering blood pressure after endovascular treatment, as there are some signs that blood pressure that’s too low may be harmful,” commented Dr. Mistry in the ASA press release. “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 customized.”

Dr. Mistry continued, “Endovascular therapy has changed the landscape in acute stroke treatment. Patients do drastically better when they receive endovascular treatment compared to when they don’t. 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.”

As noted in the ASA press release, previous research has indicated that higher systolic blood pressure after endovascular treatment is associated with greater disability in patients who have had an acute ischemic stroke. Whether using blood pressure medications to artificially lower systolic blood pressure to < 180 mm Hg is safe and effective has not been demonstrated following clot removal, noted the ASA press release.

Dr. Mistry explained, “There is always the concern if blood pressure is lowered too much in patients who are having an acute ischemic stroke that it could make the size of their stroke worse by reducing already compromised blood flow in that area.”

The BEST II investigators hypothesized that patients allocated to lowering systolic blood pressure targets might have a higher volume of stroke size at 36 hours and a higher disability at 90 days.

As summarized in the ASA press release, the investigators enrolled 120 patients (average age, 70 years; 57% female) who had an acute ischemic stroke and successful endovascular treatment at one of three urban comprehensive stroke centers (Vanderbilt University Medical Center in Nashville, Tennessee; University of Cincinnati in Cincinnati, Ohio; and Hartford Health Medical Center in Hartford, Connecticut) between January 2020 and February 2022.

Forty patients were randomly assigned to have their systolic blood pressure lowered to a target of ≤ 180 mm Hg, 40 patients were assigned to a systolic blood pressure target of < 160 mm Hg, and 40 patients were targeted to reach a systolic blood pressure of < 140 mm Hg. Patients were treated with nicardipine, an antihypertensive medication administered intravenously, started within 1 hour after endovascular treatment and given for 24 hours if their systolic blood pressure was above the target they were assigned.

The investigators assessed 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.

ASA reported that the study investigators found the following:

• In the ≤ 180 mm Hg target group, average systolic blood pressure reached 129 mm Hg.
• In the < 160 mm Hg target group, average systolic blood pressure reached 130 mm Hg.
• In the < 140 mm Hg target group, systolic blood pressure was lowered to an average of 123 mm Hg.
• The average 36-hour stroke volumes showed no conclusive evidence of harm.
• In the 90-day disability outcome, there was only a slight indication of harm.

Dr. Mistry stated, “The main outcomes of the study were the size of stroke at 36 hours and degree of disability at 90 days. 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 indication that lowering the blood pressure after thrombectomy may worsen patients’ long-term disability.”

“This study provides indication that patients’ blood pressure should be allowed to be auto regulated after endovascular treatment unless about 180 mm Hg, and clinicians might want to be cautious when they reflexively lower the blood pressure since there may be some signal of harm,” concluded Dr. Mistry. “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.”

The study’s limitations include the small number of patients involved in the trial. Additionally, because the trial was conducted at three centers, the results may not apply to stroke patients treated elsewhere, advised ASA.