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Original Investigation
July 26, 2021

Assessment of Optimal Patient Selection for Endovascular Thrombectomy Beyond 6 Hours After Symptom Onset: A Pooled Analysis of the AURORA Database

Author Affiliations
  • 1Department of Neurology and Neurological Sciences, Stanford University, Stanford, California
  • 2Stanford Stroke Center, Stanford University, Stanford, California
  • 3Bright Research Partners, Minneapolis, Minnesota
  • 4Department of Neurosurgery, Barrow Neurological Institute, Phoenix, Arizona
  • 5Department of Neurology, Marcus Stroke and Neuroscience Center, Grady Memorial Hospital, Emory University School of Medicine, Atlanta, Georgia
  • 6Federal University of Rio Grande do Sul, Porto Alegre, Brazil
  • 7Department of Clinical Neurosciences, Calgary Stroke Program, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
  • 8Department of Radiology, Calgary Stroke Program, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
  • 9Stroke Unit, Department of Neurology, Hospital Vall d’Hebron, Barcelona, Spain
  • 10Department of Neurosurgery, Prisma Health–Upstate, Greenville, South Carolina
  • 11Department of Neurology, University of California, Los Angeles, Los Angeles
  • 12UCLA Stroke Center, University of California, Los Angeles, Los Angeles
  • 13Department of Radiology and Stanford Stroke Center, Stanford University, Stanford, California
  • 14Department of Neurology, Cooper University Health Care, Camden, New Jersey
JAMA Neurol. 2021;78(9):1064-1071. doi:10.1001/jamaneurol.2021.2319
Key Points

Question  What is the optimal imaging approach for identification of patients with ischemic stroke who may benefit from endovascular thrombectomy beyond 6 hours after they were last known well?

Findings  In this pooled analysis of 6 randomized clinical trials including 505 patients with ischemic stroke, the receipt of endovascular thrombectomy was associated with a reduction in disability among patients with an imaging profile mismatch between clinical defect vs size of early infarction or size of perfusion lesion vs size of early infarction; however, this reduction in disability was not observed in the smaller group of patients with an undetermined imaging profile. Greater benefit was observed among patients with one of the mismatch profiles compared with those with an undetermined imaging profile.

Meaning  In this study, within a 6- to 24-hour treatment interval, the performance of endovascular thrombectomy among patients who had either mismatch imaging profile was associated with improvements in clinical outcomes; additional studies are needed to clarify the treatment benefit among patients with other imaging profiles.

Abstract

Importance  The optimal imaging approach for identifying patients who may benefit from endovascular thrombectomy (EVT) beyond 6 hours after they were last known well is unclear. Six randomized clinical trials (RCTs) have evaluated the efficacy of EVT vs standard medical care among patients with ischemic stroke.

Objective  To assess the benefits of EVT among patients with 3 baseline imaging profiles using a pooled analysis of RCTs.

Data Sources  The AURORA (Analysis of Pooled Data from Randomized Studies of Thrombectomy More Than 6 Hours After Last Known Well) Collaboration pooled patient-level data from the included clinical trials.

Study Selection  An online database search identified RCTs of endovascular stroke therapy published between January 1, 2010, and March 1, 2021, that recruited patients with ischemic stroke who were randomized between 6 and 24 hours after they were last known well.

Data Extraction/Synthesis  Data from the final locked database of each study were provided. Data were pooled, and analyses were performed using mixed-effects modeling with fixed effects for parameters of interest.

Main Outcomes and Measures  The primary outcome was reduction in disability measured by the modified Rankin Scale at 90 days. An evaluation was also performed to examine whether the therapeutic response differed based on imaging profile among patients who received treatment based on the time they were last known well. Treatment benefits were assessed among a clinical mismatch subgroup, a target perfusion mismatch subgroup, and an undetermined profile subgroup. The primary end point was assessed among these subgroups and during 3 treatment intervals (tercile 1, 360-574 minutes [6.0-9.5 hours]; tercile 2, 575-762 minutes [9.6-12.7 hours]; and tercile 3, 763-1440 minutes [12.8-24.0 hours]).

Results  Among 505 eligible patients, 266 (mean [SD] age, 68.4 [13.8] years; 146 women [54.9%]) were assigned to the EVT group and 239 (mean [SD] age, 68.7 [13.7] years; 126 men [52.7%]) were assigned to the control group. Among 295 patients in the clinical mismatch subgroup and 359 patients in the target perfusion mismatch subgroup, EVT was associated with reductions in disability at 90 days vs no EVT (clinical mismatch subgroup, odds ratio [OR], 3.57; 95% CI, 2.29-5.57; P < .001; target perfusion mismatch subgroup, OR, 3.13; 95% CI, 2.10-4.66; P = .001). Statistically significant benefits were observed in all 3 terciles for both subgroups, with the highest OR observed for tercile 3 (clinical mismatch subgroup, OR, 4.95; 95% CI, 2.20-11.16; P < .001; target perfusion mismatch subgroup, OR, 5.01; 95% CI, 2.37-10.60; P < .001). A total of 132 patients (26.1%) had an undetermined imaging profile and no significant treatment benefit (OR, 1.59; 95% CI, 0.82-3.06; P = .17). The interaction between treatment effects for the clinical and target perfusion mismatch subgroups vs the undetermined profile subgroup was significant (OR, 2.28; 95% CI, 1.11-4.70; P = .03).

Conclusions and Relevance  In this study, EVT was associated with similar benefit among patients in the clinical mismatch and target perfusion mismatch subgroups during the 6- to 24-hour treatment interval. These findings support EVT as a treatment for patients meeting the criteria for either of the imaging mismatch profiles within the 6- to 24-hour interval.

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