Blood Pressure–Lowering After Thrombectomy May Be Harmful

Artificially lowering blood pressure in stroke patients following endovascular therapy is not necessarily a good strategy, new research suggests.

Preliminary results of a new study showed that using an antihypertensive drug to target systolic blood pressure to below 160 mm Hg or 140 mm Hg in these patients may not be beneficial, and may even be harmful.

Dr Eva A. Mistry

"This line of inquiry is probably not worth pursuing," stroke neurologist Eva A. Mistry, MBBS, MSCI, assistant professor of clinical neurology and rehabilitation medicine, University of Cincinnati College of Medicine, Ohio, told Medscape Medical News.

Following current blood pressure guidelines in these patients (so targeting blood pressure under 180/105 mm Hg) "is probably reasonable," unless the patient's systolic blood pressure goes above 180, Mistry said. "Artificially trying to lower it may result in harm, at least in terms of the disability outcome."

The findings were presented at the International Stroke Conference (ISC) 2023.

Endovascular therapy has become standard of care for patients with large vessel occlusion after studies showed "massive benefit," yet about 50% of patients remain disabled or die at 90 days, Mistry said.

"We have been on the quest to understand if there's something we can do to improve these outcomes."

One approach could be optimizing medical management. Previous observational studies showed that higher blood pressure values after thrombectomy are associated with worse outcomes.

Taking It Forward

"We wanted to take that forward in a randomized inquiry to see first with this trial if [artificially] lowering blood pressure using medications is safe, and preliminarily understand if it could be efficacious in a larger trial," she said.

This blood pressure–lowering strategy is already practiced in some centers. A nationwide survey conducted by Mistry and her colleagues showed a wide range of targets, with some institutions aiming it as low as under 120 mm Hg after thrombectomy, which she found "surprising."

The Blood pressure after Endovascular Stroke Treatment-II (BEST-II) study included 120 ischemic stroke patients at three stroke centers, mean age 70 years and 57% female, who had undergone endovascular treatment. They were randomized to one of three target blood pressure groups: 180 mm Hg or under, less than 160 mm Hg, or under 140 mm Hg.

To lower blood pressure, researchers used intravenous nicardipine, a calcium channel blocker, as a first line. This was started within 1 hour of the endovascular treatment and given for 24 hours if the patient's systolic blood pressure was above the target of their group.

In the highest target group (less than or equal to 180 mm Hg), the average systolic blood pressure reached 129 mm Hg. In the middle target group (below 160 mm Hg), the average systolic blood pressure was 131 mm Hg, and in the lowest target group (less than 140 mm Hg), systolic blood pressure was lowered to an average of 123 mm Hg.

Mean Infarct Volumes

At 36 hours, the mean adjusted infarct volume was slightly lower in the lowest blood pressure target group (32.4) compared with the other groups (46.4 for the 180 mm Hg group and 50.7 for the under-160 mm Hg group).

"Based on a model or a slope that would be associated with serial lowering of blood pressure targets, we found the point estimate of the effect size was slightly in the direction of benefit of lower blood pressure targets in terms of lower infarct volume," Mistry said.

But this was not conclusive. While the point estimate was in the direction of benefit, Mistry stressed that the trial design doesn't "definitely rule out" the possibility of harm.

Researchers also measured functional status at 90 days with the modified Rankin Scale (mRS). They found that the utility-weighted mRS was slightly lower in the lowest blood pressure target group (0.507) compared with the higher target groups (0.584 and 0.475, respectively, for the 180 mm Hg and under-160 mm Hg groups).

"The effect size was slightly in the direction of harm," Mistry said. "To me, that means there might be safety issues associated with the lower blood pressure target."

Probably Futile

The results suggest that studying this issue further is probably futile. "If lowering blood pressure improves outcomes, that improvement is fairly marginal, and there are trends that suggest that, in fact, it might be harmful," Mistry said.

Her researcher team "believes it would not be the wisest decision" to pursue this strategy any further in a phase 3 study, she said.

"We wanted to understand whether or not we should spend millions of dollars to do a thousand-patient or two thousand-patient trial, and the answer to that is probably not."

And there are other therapeutics "we can test that might be more promising than this approach," she added.

In the meantime, Mistry stressed that clinicians should be cautious about automatically lowering blood pressure in this patient population and that decisions to target lower levels should be done on an individual basis.

Timely and Important

Commenting for Medscape Medical News, Karen Furie, MD, MPH, Chair of Neurology, Warren Alpert Medical School, Brown University, Providence, Rhode Island, said that the study is "timely and important," given the uncertainty about management of blood pressure after opening the vessel again using endovascular treatment.

"We already knew that letting the blood pressure go very high after reperfusion was bad, and this study shows that lowering it may also pose a risk, and I think that's an important message for the community."

The results send a cautionary message to clinicians but do not provide definitive evidence, she added. "Perhaps in the future we will have a better understanding of what the optimal range is."

Furie stressed that this was a small pilot study and conclusions are "guarded."

"I think the authors didn't want to over-interpret the results so they ended up concluding that because the final disability might have been worse in the patients who had their blood pressure significantly lowered, recommending that as an approach across the board is sort of discouraged."

Instead, the authors indicated that there may be factors such as degree of recanalization, size of the infarct, or other patient-specific factors "that would dictate where you target blood pressures," Furie said.

International Stroke Conference (ISC) 2023. Late-Breaking Abstract #18. Presented February 10, 2023.

The study was funded by the National Institutes of Health/National Institute of Neurological Disorders and Stroke. Mistry receives funding from the Patient-Centered Outcomes Research Institute, compensation from the American Heart Association for editorial activities, and is a consultant for RapidAI. Furie has declared no relevant financial relationships.

For more Medscape Neurology news, join us on Facebook and Twitter.

Comments

Commenting is limited to medical professionals. To comment please Log-in.

Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.