For patients with acute ischemic stroke, prolonged durations of blood pressure above or below certain thresholds during endovascular therapy may be linked to poor functional outcome, results of a retrospective study suggest.
Copyright American Stroke Association
Mean arterial blood pressure (MABP) lower than 70 mm Hg for 10 minutes or more, or higher than 90 mm Hg for 45 minutes or more, represented “critical thresholds” associated with worse neurologic outcomes, the study authors wrote in JAMA Neurology.
“These results suggest MABP may be a modifiable therapeutic target to prevent or reduce poor functional outcome in patients undergoing endovascular therapy for acute ischemic stroke, and that MABP should possibly be maintained within such narrow limits, wrote the authors, led by Mads Rasmussen, MD, PhD, of the department of anesthesia at Aarhus (Denmark) University Hospital.
The findings come from an analysis of BP data from 365 patients with acute ischemic stroke enrolled in three randomized trials evaluating different strategies for anesthesia. Among those patients, the mean age was approximately 71 years, and about 45% were women.
The investigators looked at a variety of BP-related variables during endovascular therapy to assess their impact on functional outcome, based on modified Rankin Scale (mRS) scores at 90 days.
Having an MABP below 70 mm Hg for a cumulative time of at least 10 minutes substantially increased odds of higher 90-day mRS scores (odds ratio, 1.51; 95% confidence interval, 1.02-2.22), according to Dr. Rasmussen and colleagues. The number needed to harm (NNH) at this threshold was 10; in other words, to harm 1 patient, 10 patients are needed with procedural MABP below 70 mm Hg for at least 10 minutes.
Likewise, having an MABP above 90 mm Hg for a cumulated time of at least 45 minutes significantly increased odds of higher 90-day mRS scores, with an OR of 1.49 (95% CI, 1.11-2.02) and a number needed to harm of 10.
Odds of shifting toward a worse neurologic outcome increased by 62% for every continuous 10 minutes of MABP below 70 mm Hg, and by 8% for every continuous 10 minutes above 90 mm Hg.
The maximum MABP during the procedure was significantly associated with neurologic outcomes in the study, while by contrast, maximum procedural systolic BP was not, according to the investigators.
In general, the study findings suggest that MABP is “more sensitive” than systolic BP when assessing hypotension and hypertension in these patients. However, these findings are subject to a number of limitations, the investigators wrote, including the retrospective nature of the analysis and the selected group of patients enrolled in studies designed to evaluate anesthesia strategies, not hemodynamic management.
“Randomized studies are needed to determine the optimal blood pressure management strategy during endovascular therapy,” the investigators wrote.
Dr. Rasmussen reported grant support from the Health Research Foundation of Central Denmark Region and the National Helicopter Emergency Medical Service Foundation. Coauthors reported receiving grant support from the Novo Nordisk Foundation; a research award from the Patient-Centered Outcomes Research Institute; and personal fees from Abbott Medical Sweden, I4L Innovation for Life, Boehringer Ingelheim, Medtronic, and Zoll.
SOURCE: Rasmussen M et al. JAMA Neurol. 2020 Jan 27. doi: 10.1001/jamaneurol.2019.4838.