Two post-hoc analyses show no interaction between these factors and either functional outcomes or risk of symptomatic intracranial hemorrhage.
Neither blood pressure nor serum glucose level thresholds should be employed to eliminate stroke patient as candidates for intra-arterial interventions, according to two post-hoc analyses of the MR CLEAN trial that were published last month in Stroke. While suboptimal values are associated with poorer outcomes, patients clearly still benefit from the intervention, researchers say.
Blood Pressure Study
In an interview with Neurovascular Exchange, Maxim J.H.L. Mulder, MD (Erasmus University Medical Center, Rotterdam, the Netherlands), who led the blood pressure study, explained that American Heart Association and American Stroke Association guidelines recommend against use of IV thrombolysis for the treatment of stroke among patients with a blood pressure above 185/110 mm Hg. They make no recommendation about intra-arterial treatment and blood pressure, however, because of the paucity of data on this issue.
To help clarify the matter, Mulder and colleagues used the MR CLEAN data to calculate the correlation between baseline blood pressure and 90-day mRS as well as safety parameters.
Systolic blood pressure correlated with mRS score in a U-shaped fashion, such that both low and high baseline systolic blood pressures were associated with poorer functional outcomes. In addition, higher systolic blood pressure was associated with a greater risk of symptomatic intracranial hemorrhage (adjusted OR 1.25 per 10-mm Hg increase; 95% CI 1.09-1.44).
Importantly, there was no interaction between systolic blood pressure and intra-arterial therapy with respect to functional outcome, symptomatic intracranial hemorrhage, or other safety parameters. In other words, the treatment benefit was evident for the whole range of systolic blood pressure. A similar pattern was found for diastolic blood pressure.
“The main finding is that . . . blood pressure is indeed associated with functional outcome for patients with a large vessel occlusion,” said Mulder. “But most importantly, blood pressure does not interact with intra-arterial treatment effect.” He likened the relationship to that of patient age—despite older age being associated with poorer functional outcomes in all large vessel occlusion patients, intra-arterial treatment remains beneficial even for the very elderly. Therefore, older age alone is not a barrier to the intervention, Mulder noted.
Serum Glucose Study
There are similar uncertainties about the effect of hyperglycemia on outcomes of intra-arterial therapy. “Patients with hyperglycemia are at increased risk of poor functional outcome, symptomatic intracranial hemorrhage, and less successful revascularization after intra-arterial thrombolysis,” write Elizabeth Osei, MD, (Medisch Spectrum Twente, Enschede, the Netherlands), and colleagues in their analysis of MR CLEAN. “Less evidence is available for patients who have been treated with intra-arterial thrombectomy.”
Osei et al examined the correlation between hyperglycemia at admission (defined as serum glucose > 7.8 mmol/L) and improvement in 90-day mRS as well as risk of symptomatic intracranial hemorrhage. Mean admission glucose was 7.2 mmol/L for the 487 patients included in the analysis. In both treatment arms, around one-quarter of patients were hyperglycemic.
As with blood pressure, there was no significant interaction between either hyperglycemia or \serum glucose levels at admission and the effect of intra-arterial treatment on mRS score or risk of symptomatic hemorrhage.
Mulder emphasized that the studies provide no information on how (or even whether) to treat blood pressure and serum glucose levels that fall outside of an ideal range. It is possible, for instance, that high blood pressure is a protective biological mechanism and that lowering it could worsen outcomes even more. This remains an important question for future research.
“If you have acute ischemic stroke patients with a blood pressure above the IV threshold, then you cannot treat with IV [thrombolysis] given the guidelines,” he said. “I would proceed as soon as possible with CT angiography to see if they are a possible candidate for intra-arterial treatment. If they have a proximal occlusion, I would definitely go for intra-arterial treatment because we know that removing the occlusion is beneficial despite the blood pressure.”
Similarly, he said, hyperglycemia should not be a barrier to intra-arterial treatment, which has been shown to be beneficial at every serum glucose level.
Sources:
- Mulder MJHL, Ergezen S, Lingsma HF, et al. Baseline blood pressure effect on the benefit and safety of intra-arterial treatment in MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment of Acute Ischemic Stroke in the Netherlands). Stroke. 2017;Epub ahead of print.
- Osei E, den Hertog HM, Berkhemer OA, et al. Admission glucose and effect of intra-arterial treatment in patients with acute ischemic stroke. Stroke. 2017;Epub ahead of print.
Disclosures:
- MR CLEAN was funded by the Dutch Heart Foundation and by unrestricted grants from AngioCare Besloten Vennootschap, Medtronic/ Covidien/ev3, Medac Gesellschaft mit beschränkter Haftung/ Lamepro, Penumbra Incorporated, Stryker, and Top Medical/ Concentric.
- Osei and Mulder report no relevant conflicts of interest.
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