Worse disability scores
Results showed that the patients who underwent the more intensive blood pressure lowering had more disability at 3-month follow-up, with worse scores on a shift analysis of the mRS than those in the less intensive group (common odds ratio, 1.37; 95% confidence interval, 1.07-1.76).
The unfavorable shift in mRS scores in the more intensive group was consistent in adjusted sensitivity analysis, and there was no significant heterogeneity in the treatment effect on the primary outcome across all prespecified subgroups.
The incidence of death or neurologic deterioration at 7 days was higher in the more intensive-treatment group than the less intensive-treatment group (common OR, 1.53), and a between-group difference emerged at 24 hours.
The incidence of death or disability (mRS scores, 3-6) at 90 days was higher among patients in the more intensive-treatment group than the less intensive-treatment group (53% vs. 39%; OR, 1.85; P = .0001).
Among those who survived, more patients in the more intensive-treatment group had major disability (mRS scores, 3-5) at 90 days than did patients in the less intensive-treatment group (43% vs. 28%; OR, 2.07; P = .0001).
No difference in ICH or severe hypotension episodes
The incidence of symptomatic intracranial hemorrhage, mortality, and serious adverse events did not significantly differ between the two groups. There were no significant differences in recurrent ischemic stroke events at 90 days, and no episodes of severe hypotension were reported as a serious adverse event.
“Our results show that intensive lowering of blood pressure appears to be associated with worsening physical disability. While there was no difference in mortality rates between the two groups, the lower blood pressure appeared to compromise the ability to recover from the stroke,” Dr. Anderson said.
On the possible mechanism of harm, he suggested that the intensive blood pressure reduction might be interfering with blood flow through the injured part of the brain and impeding the ability to recover from the clot removal procedure.
What levels should be aimed for?
Dr. Anderson stressed that it was important to have conducted this trial.
“Current guidelines recommend very conservative level of blood pressure in acute ischemic stroke patients – to below 180 mm Hg. But no lower limit is recommended.
“Most clinicians aim for about the 140 mm Hg mark, but there is a large variation in opinion on what to do,” he said. “Some doctors treat aggressively, believing that lower pressures could be beneficial in preventing bleeding and swelling, and others prefer to keep levels higher. Our results have helped to give some guidance on this.”
Asked what he thought an optimum target would be, Dr. Anderson replied: “For now, I think a target of around 140 mm Hg systolic would be reasonable, and there is no evidence to move below that.”
Yvo Roos, MD, professor of acute neurology at University Medical Center, Amsterdam, a co-author of the ENCHANTED2/MT trial, also commented: “The real importance of these study results is that they show that lowering blood pressure too much is detrimental on outcome. My personal interpretation, looking at the results of this study but also on the previous studies, is that we should aim for a target of 140-150 mm Hg. This is true for patients with recanalization therapy. For patients without any therapy, I would even be more careful in lowering blood pressure and recommend just staying below 180 mm Hg.”
As to whether these results are generalizable to other populations, given that the patients were Chinese, Dr. Anderson noted that Asian people have higher rates of intracranial atherosclerosis and more blood pressure complications in the heart and kidney than White patients. Stroke management patterns also differ.
“These points raise questions about generalizability, and while I think this is an issue for consideration, I do not think it should detract from the clarity of these results,” he commented.
The study is supported by grants from the Shanghai Hospital Development Center, the National Health and Medical Research Council of Australia, the China Stroke Prevention Project, Shanghai Changhai Hospital, the Science and Technology Commission of Shanghai Municipality, Takeda China, Genesis Medtech, and Penumbra. Dr. Anderson has received grants from the National Health and Medical Research Council and Medical Research Futures Fund of Australia, the UK Medical Research Council, Penumbra, and Takeda China.
A version of this article first appeared on Medscape.com.