Endovascular Therapy for Ischemic Stroke with Perfusion-Imaging Selection¶
Why this mattered¶
EXTEND-IA mattered because it helped convert endovascular stroke therapy from an uncertain, inconsistently successful intervention into a biologically targeted treatment. Earlier thrombectomy trials had been mixed, in part because they often used older devices, enrolled patients without reliably confirming a treatable large-vessel occlusion, or did not select for a substantial mismatch between irreversibly infarcted tissue and salvageable penumbra. This trial showed that, in patients already receiving alteplase, rapid thrombectomy with a modern stent retriever could produce near-complete reperfusion and substantially better early neurologic recovery when CT perfusion identified a small ischemic core and viable threatened tissue.
Its importance was not only the positive result, but the model of treatment it validated: acute ischemic stroke could be triaged by vessel status and tissue physiology, not just by clock time. The trial’s small size and early stopping mean it was one piece of a larger evidence shift rather than a standalone revolution, but alongside MR CLEAN, ESCAPE, SWIFT PRIME, and REVASCAT it helped establish mechanical thrombectomy as standard care for anterior-circulation large-vessel occlusion. EXTEND-IA was especially influential in demonstrating that advanced imaging could identify patients most likely to benefit, making reperfusion therapy more selective, faster, and more mechanistically grounded.
That imaging-selection paradigm directly shaped later breakthroughs that expanded the treatment window. Trials such as DAWN and DEFUSE 3 built on the same core idea: some patients retain salvageable brain tissue well beyond traditional time limits, and perfusion or clinical-core mismatch can identify them. In that sense, EXTEND-IA helped move stroke care toward the modern “tissue clock” framework, where thrombectomy decisions depend on demonstrable threatened-but-viable brain rather than onset time alone.
Abstract¶
BACKGROUND: Trials of endovascular therapy for ischemic stroke have produced variable results. We conducted this study to test whether more advanced imaging selection, recently developed devices, and earlier intervention improve outcomes. METHODS: We randomly assigned patients with ischemic stroke who were receiving 0.9 mg of alteplase per kilogram of body weight less than 4.5 hours after the onset of ischemic stroke either to undergo endovascular thrombectomy with the Solitaire FR (Flow Restoration) stent retriever or to continue receiving alteplase alone. All the patients had occlusion of the internal carotid or middle cerebral artery and evidence of salvageable brain tissue and ischemic core of less than 70 ml on computed tomographic (CT) perfusion imaging. The coprimary outcomes were reperfusion at 24 hours and early neurologic improvement (≥8-point reduction on the National Institutes of Health Stroke Scale or a score of 0 or 1 at day 3). Secondary outcomes included the functional score on the modified Rankin scale at 90 days. RESULTS: The trial was stopped early because of efficacy after 70 patients had undergone randomization (35 patients in each group). The percentage of ischemic territory that had undergone reperfusion at 24 hours was greater in the endovascular-therapy group than in the alteplase-only group (median, 100% vs. 37%; P<0.001). Endovascular therapy, initiated at a median of 210 minutes after the onset of stroke, increased early neurologic improvement at 3 days (80% vs. 37%, P=0.002) and improved the functional outcome at 90 days, with more patients achieving functional independence (score of 0 to 2 on the modified Rankin scale, 71% vs. 40%; P=0.01). There were no significant differences in rates of death or symptomatic intracerebral hemorrhage. CONCLUSIONS: In patients with ischemic stroke with a proximal cerebral arterial occlusion and salvageable tissue on CT perfusion imaging, early thrombectomy with the Solitaire FR stent retriever, as compared with alteplase alone, improved reperfusion, early neurologic recovery, and functional outcome. (Funded by the Australian National Health and Medical Research Council and others; EXTEND-IA ClinicalTrials.gov number, NCT01492725, and Australian New Zealand Clinical Trials Registry number, ACTRN12611000969965.).
Related¶
- cite → A Simple Sequentially Rejective Multiple Test Procedure — The stroke trial uses Holm's sequentially rejective procedure to control family-wise error across multiple statistical comparisons.
- cite → A Randomized Trial of Intraarterial Treatment for Acute Ischemic Stroke — The perfusion-imaging stroke trial follows MR CLEAN's evidence that intraarterial endovascular therapy improves outcomes in acute ischemic stroke.
- enables ← A Simple Sequentially Rejective Multiple Test Procedure — Holm's sequentially rejective procedure supplied family-wise error control for multiple outcome testing in the ischemic-stroke trial.