Prehospital trials pose particular challenges
HONOLULU – Acute ischemic stroke patients who underwent endovascular thrombectomy and then had a peak systolic blood pressure of greater than 158 mm Hg during the next 24 hours had worse 90-day outcomes than did patients whose peak systolic pressure remained at or below 158 mm Hg in a prospective, multicenter, observational study with 485 patients.
Mitchel L. Zoler/MDedge News
Dr. Eva A. Mistry
The results hint that maintaining a lower systolic blood pressure after thrombectomy in acute ischemic stroke patients may improve outcomes, but because the current study was observational, the hypothesis that patients benefit when treatment keeps their systolic pressure at or below 158 mm Hg must undergo testing in a prospective, randomized trial, Eva A. Mistry, MBBS, said at the International Stroke Conference, sponsored by the American Heart Association.
The finding from this study that 158 mm Hg provided the best dichotomous division between systolic blood pressures linked with good or bad outcomes is a first step toward trying to devise a more systematic and evidence-based approach to blood pressure management in acute ischemic stroke patients following endovascular thrombectomy, said Dr. Mistry, a neurologist at Vanderbilt University in Nashville, Tenn.
Neither Vanderbilt nor any of the other 11 major U.S. stroke centers that participated in the current study currently have an established protocol for blood pressure management after thrombectomy, Dr. Mistry said in an interview.
“We usually treat to reduce blood pressure, but we don’t have a [broadly agreed on] threshold” to trigger treatment. “It depends on a collective decision” by the various medical specialists who care for an individual acute stroke patient. In addition, no consensus yet exists for the best treatment strategy for blood pressure lowering in acute ischemic stroke patients. Intravenous nicardipine is often the top choice because it is fast-acting and easy to administer and control as an intravenous agent. Those same properties make the beta blocker labetalol a frequently used second drug, she said.
The BEST (Blood Pressure After Endovascular Stroke Therapy) study ran at 12 U.S. centers and enrolled 485 patients who underwent endovascular thrombectomy to treat an acute ischemic stroke. The patients averaged 69 years old, and 48% also underwent thrombolytic treatment. The study’s primary outcome was the percentage of patients with a modified Rankin Scale score of 0-2 at 90 days after their stroke, an outcome reached by 39% of all patients in the study.
Statistical analysis of the collected data showed that a peak systolic blood pressure of 158 mm Hg reached during the 24 hours following thrombectomy best divided patients with good 90-day outcomes from those with worse outcomes. Patients with a postthrombectomy peak systolic pressure above 158 mm Hg had a 2.2-fold increased rate of having a modified Rankin Scale score of 3 or higher after 90 days, a statistically significant relationship, Dr. Mistry reported. However, in an analysis that also adjusted for age, baseline stroke severity, glucose level, time to reperfusion, ASPECTS score, history of hypertension, and recanalization status, the elevated risk for a bad outcome linked with higher systolic pressure dropped to 39% greater than that for patients with systolic pressures that did not rise above 158 mm Hg, a difference that was not statistically significant. This suggests that these adjustments were unable to account for all confounders and further highlighted the need for a prospective, randomized trial to test the value of controlling blood pressure following thrombectomy, Dr. Mistry said. The unadjusted results confirmed a prior report from Dr. Mistry and her associates that found a link between higher blood pressure after stroke thrombectomy and worse outcomes (J Am Heart Assoc. 2017 May 18. doi: 10.1161/JAHA.117.006167).
The analysis also showed that patients who were successfully recanalized by thrombectomy, achieving a thrombolysis in cerebral infarction (TICI) score of 2b or 3, had lower peak systolic blood pressures than did patients who failed to get this level of restored cerebral blood flow from thrombectomy.
BEST received no commercial funding. Dr. Mistry had no disclosures.
SOURCE: Mistry EA et al. Stroke. 2019 Feb;50(Suppl_1): Abstract 94.