MUNICH — Intensive systolic blood pressure (SBP) management in the 24 hours after successful recanalization with intra-arterial thrombectomy (IAT) substantially increases the risk of a poor outcome at 3 months, suggests results from the OPTIMAL-BP trial.
The research, presented May 26 at the 9th European Stroke Organisation Conference (ESOC), supports the latest US and European guidelines, which recommend a relatively high upper SBP limit.
For the trial, which was halted early, over 300 patients who successfully underwent IAT for acute ischemic stroke were randomly assigned to intensive or conventional blood pressure management within 2 hours of recanalization.
Patients in the intensive group were 44% less likely than those assigned to conventional management to have a favorable outcome of a modified Rankin Scale score of 0-2 at 3 months, while having similar rates of adverse outcomes.
The results suggest that intensive blood pressure lowering in the 24 hours after recanalization leads to an increased risk of disability without decreasing the risk of intracerebral hemorrhage (ICH) or death, said study presenter Hyo Suk Nam, MD, PhD, Department of Neurology, Yonsei University College of Medicine, Yonsei, South Korea.
Consequently, the trial "does not support intensive blood pressure management" in that early post-IAT period, although the "optimal blood pressure range remains unclear and requires more investigation," he said.
Nam added that the results suggest, "despite recanalization, some areas in the ischemic brain may have already been damaged," or that surrounding areas continue to have reduced blood circulation.
He believes that these areas may have reduced capacity for autoregulation and so "may not effectively counteract sudden drops in blood pressure."
"Thus, intensive blood pressure lowering may further reduce blood flow…and exacerbate ischemic injury."
On the other hand, the conventional group confirmed prior studies indicating that high SBP is associated with poor outcomes.
Nam suggested that increased blood pressure "may be a physiological response to the acute stress of stroke," but that the adverse outcomes in some patients "might reflect stroke severity rather than being a direct effect of raised blood pressure."
Session co-chair Carlos Molina, MD, director of the Stroke Unit and Brain Hemodynamics at Vall d'Hebron Hospital, Barcelona, Spain, commented that "it's very important to remember that the guidances are endorsed by the results of this study.
He told Medscape Medical News that "intensive blood pressure lowering harms the brain, especially just after reperfusion."
"So, the results are in line with the previous concept that we need to be careful, as intensive blood pressure lowering is associated with clinical deterioration and poor outcomes."
He agreed with Nam that, with high blood pressure also being harmful, the optimal range is currently unclear.
Molina underlined, however, that, in the absence of further studies, "we have to stick to the guidelines."
Nam pointed out that, while high blood pressure can result in reperfusion injury or ICH, "too low blood pressure can worsen cerebral ischemia."
Yet the management of blood pressure after successful recanalization with IAT is "largely unknown."
He noted that, while both the European Stroke Organisation and American Heart Association/American Stroke Association guidelines recommend that blood pressure should be kept below 180/105 mmHg in patients who have undergone successful recanalization, the evidence class for this recommendation is "weak."
Furthermore, observational studies have indicated that higher maximum or average systolic blood pressure is associated with poor outcomes, but two multicenter clinical trials of intensive blood pressure lowering after IAT, BP-TARGET and ENCHANTED2/MT, had conflicting results.
The researchers therefore investigated whether intensive blood pressure management would result in better clinical outcomes in the 24 hours after successful recanalization with IAT.
They conducted a multicenter, open-label trial in which patients aged 20 years and older who underwent IAT for acute ischemic stroke with large cerebrovascular occlusion and had an SBP ≥140 mm Hg were recruited from 19 centers in South Korea between June 2020 and November 2022.
The patients were randomly assigned within 2 hours of successful recanalization to intensive blood pressure management, targeting an SBP <140 mm Hg, or conventional management, targeting an SBP of 140-180 mm Hg.
Clinicians could use local treatment protocols based on available IV blood pressure-lowering drugs. Blood pressure was measured every 15 minutes for the first hour after randomization and then hourly for 24 hours.
The trial was terminated early because of safety concerns after the ENCHANTED2/MT trial revealed a negative impact on modified Rankin scale scores at 3 months with intensive blood pressure management.
Of 1606 potentially eligible patients with acute ischemic stroke treated with IAT, 306 were randomly assigned, with 155 in the intensive group and 150 in the conventional group included in the primary analysis.
The mean age was 73.1 years, and 40.3% were women. The average National Institutes of Health Stroke Scale (NIHSS) score prior to IAT was 13. The mean time from stroke onset to randomization was 480 minutes (8 hours) (interquartile range 320-820 minutes [5.3-13.6 hrs]).
At 24 hours, the mean SBP in the intensive group was 129.2 mm Hg versus 138.0 mm Hg in the conventional group, for a between group difference of 9.6 mm Hg (95% CI, -12.2 to -6.9, P < .001).
Patients in the intensive group spent 80.3% of the first 24 hours with SBP <140 mm Hg vs 54.2% in the conventional group (P < .001). In contrast, conventional group patients spent 42.1% of the first 24 hours with SBP 140-180 mm Hg vs 14.2% in the intensive group.
Crucially, Nam showed that patients in the intensive blood pressure lowering group were significantly less likely than those in the conventional group to have a favorable outcome, defined as a modified Rankin scale score of 0-2, at 3 months, at 39.4% vs 54.4%, or an adjusted odds ratio (AOR) of 0.56 (95% CI, 0.33 - 0.96, P = .034).
Moreover, a poor outcome was 1.84 (95% CI, 1.17 - 2.91) times more common in the intervention group than the conventional group, Nam reported, with a number needed to harm of 6.6.
In terms of safety, there was no significant difference in rates of symptomatic ICH between the groups, at 9% in the intensive vs 8.1% in the conventional groups, or an AOR of 1.10 (95% CI, 0.48 - 2.53, P = .816).
There was also no difference in the rate of death related to the index stroke within 90 days, at 7.7% vs 5.4% (AOR, 1.73; 95% CI, 0.61 - 4.92, P = .307).
There were also no significant differences between the groups in key secondary outcomes, such as NIHSS score at 24 hours, recanalization at 24 hours, favorable outcome on the modified Rankin scale at one month, and the EQ-5D-3L quality of life score.
However, patients in the intensive group were substantially more likely to experience malignant brain edema, at 7.7% vs 1.3% in the conventional group (AOR, 7.88; 95% CI, 1.57 - 39.39, P = .012).
Restricted cubic spline regression analysis indicated that there was a U-shaped relationship between mean SBP during the 24 hours following IAT and the odds ratio of a poor outcome, in which both a low and a high blood pressure were unfavorable.
Nam cautioned that, when interpreting the results, the early termination of the study may have reduced its statistical power and increased the likelihood of random and exaggerated treatment effects.
He also noted that the study was conducted in South Korea, and so the results may not be generalizable to other populations.
The study received a grant from the Patient-Centered Clinical Research Coordinating Center, funded by the Ministry of Health and Welfare. No relevant financial relationships declared.
9th European Stroke Organisation Conference (ESOC) 2023: Abstract 3079. Presented May 26, 2023.
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Cite this: Intensive BP Reduction After Stroke Recanalization Harmful - Medscape - May 31, 2023.
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