Immediate Recanalization of Large-Vessel Occlusions by Tissue Plasminogen Activator Occurs in 28% of Patients Treated in a Mobile Stroke Unit

BACKGROUND: Recanalization of cerebral large-vessel occlusions (LVOs) by intravenous thrombolysis is infrequent but has been relatively unexplored with ultraearly treatment. We evaluated prehospital treatment with tissue plasminogen activator (tPA) in a mobile stroke unit to explore the recanalization rate in patients with LVOs and its effect on early clinical improvement and long-term disability. METHODS: Prospectively collected data were analyzed from Houston mobile stroke unit patients who were treated with tPA and had LVOs identified by either hyperdense arteries on computed tomography or arterial occlusion on computed tomography angiography while on board the mobile stroke unit. The primary outcome was immediate recanalization (IRC), categorized as resolution of LVO on repeat vascular imaging in the emergency department (ED) or on emergent angiography. The secondary outcome was change in National Institutes of Health Stroke Scale from baseline and modified Rankin score at 90 days. RESULTS: Sixty-nine patients with anterior or posterior circulation LVOs were enrolled; the median time from last known normal to tPA bolus was 64.0 minutes (interquartile range, 52.0-89.0). Nineteen patients (28%) had IRC, with 11 based on computed tomography angiography on ED arrival and 8 based on first run of emergent angiography. Median time from tPA bolus to documentation of IRC was 61.0 minutes (interquartile range, 42.0-111.0). IRC was associated with improvement in median National Institutes of Health Stroke Scale from baseline (17.0 [14.0-22.0]) to ED arrival (10.0 [5.5-16.5]) and to 24 hours (4.0 [0.5-10.5]). Of the non-IRC patients, 41 had recanalization after endovascular thrombectomy and 9 did not receive recanalization. The IRC group, earlier last known normal to tPA bolus, greater baseline National Institutes of Health Stroke Scale, and M1 and M2 middle cerebral artery occlusion locations were independently associated with greater improvement in National Institutes of Health Stroke Scale from baseline to ED arrival. The 90-day modified Rankin score distribution was best in the IRC group, followed by the delayed recanalization group, and both had significantly less disability than the no recanalization group (P=0.002). CONCLUSIONS: Recanalization by ED arrival occured in 28% of patients with LVO who received tPA treatment in a mobile stroke unit and results in early clinical improvement and less disability at 90 days.