Blood Pressure Thresholds and Neurologic Outcomes After Endovascular Therapy for Acute Ischemic Stroke: An Analysis of Individual Patient Data From 3 Randomized Clinical Trials

Abstract

Importance: The optimal blood pressure targets during endovascular therapy (EVT) for acute ischemic stroke (AIS) are unknown.

Objective: To study whether procedural blood pressure parameters, including specific blood pressure thresholds, are associated with neurologic outcomes after EVT.

Design, setting, and participants: This retrospective cohort study included adults with anterior-circulation AIS who were enrolled in randomized clinical trials assessing anesthetic strategy for EVT between February 2014 and February 2017. The trials had comparable blood pressure protocols, and patients were followed up for 90 days. A total of 3630 patients were initially approached, and 3265 patients were excluded.

Exposure: Endovascular therapy.

Main outcomes and measures: The primary efficacy variable was functional outcome as defined by the modified Rankin Scale (mRS) score at 90 days. Associations of blood pressure parameters and time less than and greater than mean arterial blood pressure (MABP) thresholds with outcome were analyzed.

Results: Of the 365 patients included in the analysis, the mean (SD) age was 71.4 (13.0) years, 163 were women (44.6%), and the median National Institutes of Health Stroke Scale score was 17 (interquartile range [IQR], 14-21). For the entire cohort, 182 (49.9%) received general anesthesia and 183 (50.1%) received procedural sedation. A cumulated period of minimum 10 minutes with less than 70 mm Hg MABP (adjusted OR, 1.51; 95% CI, 1.02-2.22) and a continuous episode of minimum 20 minutes with less than 70 mm Hg MABP (adjusted OR, 2.30; 95% CI, 1.11-4.75) were associated with a shift toward higher 90-day mRS scores, corresponding to a number needed to harm of 10 and 4, respectively. A cumulated period of minimum 45 minutes with greater than 90 mm Hg MABP (adjusted OR, 1.49; 95% CI, 1.11-2.02) and a continuous episode of minimum 115 minutes with greater than 90 mm Hg MABP (adjusted OR, 1.89; 95% CI, 1.01-3.54) were associated with a shift toward higher 90-day mRS scores, corresponding to a number needed to harm of 10 and 6, respectively.

Conclusions and relevance: Critical MABP thresholds and durations for poor outcome were found to be MABP less than 70 mm Hg for more than 10 minutes and MABP greater than 90 mm Hg for more than 45 minutes, both durations with a number needed to harm of 10 patients. Mean arterial blood pressure may be a modifiable therapeutic target to prevent or reduce poor functional outcome after EVT.

Conflict of interest statement

Conflict of Interest Disclosures: Dr Rasmussen was supported by a grant from the Health Research Foundation of Central Denmark Region and the National Helicopter Emergency Medical Service Foundation, Denmark. Dr Simonsen is supported by a grant from The Novo Nordisk Foundation. Dr Rentzos has received personal fees from Abbott Medical Sweden and I4L Innovation for Life PC. Dr Bösel has received personal fees from Boehringer Ingelheim, Medtronic, and Zoll, and an unrelated research award from Patient-Centered Outcomes Research Institute. No other disclosures were reported.

Figures

Figure 1.. Schematic Presentation of Fluctuations in Mean Arterial Blood Pressure (MABP) Around Upper and Lower Thresholds

Cumulated time (minutes) and longest continuous episode (minutes) less than and greater than specific thresholds are defined. Change in MABP (Δ MABP) is calculated as the magnitude of the difference between baseline MABP and the average of all MABP values measured during the procedure., The blue dot indicates baseline and the diamond indicates end of endovascular therapy. aLongest continuous episode with MABP less than lower threshold. bCombined with period A for cumulated time with MABP less than lower threshold. cLongest continuous episode with MABP greater than upper threshold. dCombined with period C for cumulated time with MABP greater than upper threshold. eChange in MABP.

Figure 2.. Spline Plots of Cumulated Time (Minutes) and Longest Continuous Episode (Minutes) Less Than Lower and Greater Than Upper Mean Arterial Blood Pressure (MABP) Thresholds vs Adjusted Odds Ratio (OR)

A, Cumulated time with MABP less than 70 mm Hg vs adjusted OR (95% CI) for shift toward worse 90-day outcome. B, Longest continuous episode with MABP less than 70 mm Hg vs adjusted OR (95% CI) for a shift toward worse 90-day outcome. C, Cumulated time with MABP greater than 90 mm Hg vs adjusted OR (95% CI) for a shift toward worse 90-day outcome. D, Longest continuous episode with MABP over 90 mm Hg vs adjusted OR (95% CI) toward worse 90-day outcome.