IMPORTANCE Optimal management of sedation and airway during thrombectomy for acute ischemic stroke is controversial due to lack of evidence from randomized trials. OBJECTIVE To assess whether conscious sedation is superior to general anesthesia for early neurological improvement among patients receiving stroke thrombectomy. DESIGN, SETTING, AND PARTICIPANTS SIESTA (Sedation vs Intubation for Endovascular Stroke Treatment), a single-center, randomized, parallel-group, open-label treatment trial with blinded outcome evaluation conducted at Heidelberg University Hospital in Germany (April 2014-February 2016) included 150 patients with acute ischemic stroke in the anterior circulation, higher National Institutes of Health Stroke Scale (NIHSS) score (>10), and isolated/combined occlusion at any level of the internal carotid or middle cerebral artery.INTERVENTION Patients were randomly assigned to an intubated general anesthesia group (n = 73) or a nonintubated conscious sedation group (n = 77) during stroke thrombectomy.MAIN OUTCOMES AND MEASURES Primary outcome was early neurological improvement on the NIHSS after 24 hours (0-42 [none to most severe neurological deficits; a 4-point difference considered clinically relevant]). Secondary outcomes were functional outcome by modified Rankin Scale (mRS) after 3 months (0-6 [symptom free to dead]), mortality, and peri-interventional parameters of feasibility and safety. RESULTS Among 150 patients (60 women [40%]; mean age, 71.5 years; median NIHSS score, 17), primary outcome was not significantly different between the general anesthesia group (mean NIHSS score, 16.8 at admission vs 13.6 after 24 hours; difference, −3.2 points [95% CI, −5.6 to −0.8]) vs the conscious sedation group (mean NIHSS score, 17.2 at admission vs 13.6 after 24 hour; difference, −3.6 points [95% CI, −5.5 to −1.7]); mean difference between groups, −0.4 (95% CI, −3.4 to 2.7; P = .82). Of 47 prespecified secondary outcomes analyzed, 41 showed no significant differences. In the general anesthesia vs the conscious sedation group, substantial patient movement was less frequent (0% vs 9.1%; difference, 9.1%; P = .008), but postinterventional complications were more frequent for hypothermia (32.9% vs 9.1%; P < .001), delayed extubation (49.3% vs 6.5%; P < .001), and pneumonia (13.7% vs 3.9%; P = .03). More patients were functionally independent (unadjusted mRS score, 0 to 2 after 3 months [37.0% in the general anesthesia group vs 18.2% in the conscious sedation group P = .01]). There were no differences in mortality at 3 months (24.7% in both groups).CONCLUSIONS AND RELEVANCE Among patients with acute ischemic stroke in the anterior circulation undergoing thrombectomy, conscious sedation vs general anesthesia did not result in greater improvement in neurological status at 24 hours. The study findings do not support an advantage for the use of conscious sedation.