Purpose To study the relationship between functional independence and time to reperfusion in the Solitaire with the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke (SWIFT PRIME) trial in patients with disabling acute ischemic stroke who underwent endovascular therapy plus intravenous tissue plasminogen activator (tPA) administration versus tPA administration alone and to investigate variables that affect time spent during discrete steps. Materials and Methods Data were analyzed from the SWIFT PRIME trial, a global, multicenter, prospective study in which outcomes were compared in patients treated with intravenous tPA alone or in combination with the Solitaire device (Covidien, Irvine, Calif). Between December 2012 and November 2014, 196 patients were enrolled. The relation between time from (a) symptom onset to reperfusion and (b) imaging to reperfusion and clinical outcome was analyzed, along with patient and health system characteristics that affect discrete steps in patient workflow. Multivariable logistic regression was used to assess relationships between time and outcome; negative binomial regression was used to evaluate effects on workflow. The institutional review board at each site approved the trial. Patients provided written informed consent, or, at select sites, there was an exception from having to acquire explicit informed consent in emergency circumstances. Results In the stent retriever arm of the study, symptom onset to reperfusion time of 150 minutes led to 91% estimated probability of functional independence, which decreased by 10% over the next hour and by 20% with every subsequent hour of delay. Time from arrival at the emergency department to arterial access was 90 minutes (interquartile range, 69-120 minutes), and time to reperfusion was 129 minutes (interquartile range, 108-169 minutes). Patients who initially arrived at a referring facility had longer symptom onset to groin puncture times compared with patients who presented directly to the endovascular-capable center (275 vs 179.5 minutes, P < .001). Conclusion Fast reperfusion leads to improved functional outcome among patients with acute stroke treated with stent retrievers. Detailed attention to workflow with iterative feedback and aggressive time goals may have contributed to efficient workflow environments. (©) RSNA, 2016 Online supplemental material is available for this article.