Abstract 1122‐000126: Mobile Stroke Unit Process Metrics in Large Vessel Occlusion Stroke Patients: BEST‐MSU Substudy

Abstract

Introduction: Mobile Stroke Units (MSUs) speed thrombolytic treatment for acute ischemic stroke and improve clinical outcomes compared to standard management by Emergency Medical Services (EMS). However, MSU process metrics in the subset of patients with large vessel occlusions (LVOs) having endovascular thrombectomy (EVT) have yet to be optimized. Methods: A pre‐specified Benefits of Stroke Treatment Using a Mobile Stroke Unit (BEST‐MSU) substudy of tPA‐eligible stroke patients with imaging evident LVOs was conducted. The primary outcome was process metrics related to treatment times from stroke onset and first medical alert. Safety outcomes included rates of symptomatic intracerebral hemorrhage and procedural complications. Groups were compared using Chi‐square or Fisher’s exact tests for categorical variables, and Wilcoxon rank‐sum tests for continuous variables. Results: A total of 295 patients were included, 169 in the MSU group and 126 in the EMS group. Baseline characteristics were comparable between the groups, with the exception of baseline NIHSS (MSU mean 19.0 [IQR 13.0,23.0] vs EMS 16.0 [11.0, 20.0], p = 0.003). 92% of MSU and 87% of EMS LVO patients received tPA, and 78% and 85% went on to have EVT. Process metrics are detailed in Table 1. MSU LVO patients had faster tPA bolus from 911‐alert (MSU 45.0 minutes [40.0, 53.5] vs EMS 76.0 [64.0, 87.8], p<0.001), however the two groups had similar alert to groin puncture (MSU 142.5 [116.8, 171.0] versus EMS 131.5 [114.0, 159.8], p = 0.15). MSU patients spent more time on‐scene, (EMS arrival to ED arrival, 53.0 [45.0, 62.0] vs 27.0 [22.0, 33.0], p<0.001) however less time prior to EVT (door to groin puncture, 76.5 [54.8, 108.5] vs 94.0 [72.0, 123.0], p<0.001) with variable use of field CTAs and direct cath lab admission with ED bypass, yielding a net neutral result. The variability among site protocols is reflected in the range of median alert to groin puncture times (minimum 107.0 minutes, maximum 152.0). In the 222 patients undergoing EVT, median alert to recanalization time was 181.5 minutes [146.8, 225.5] in the MSU group and 190.5 [157.5, 227.5] in the EMS group (p = 0.47). Recanalization (Thrombolysis In Cerebral Infarction [TICI] 2b/3) was achieved in 76% of MSU and 70% of EMS (p = 0.32) with comparable rates of EVT complications (including hemorrhage, perforation, dissection, hematoma). 54% MSU and 44% of EMS LVO patients achieved good functional outcome (modified Rankin Scale [mRS] ≤ 2) at 90 days (p = 0.11). Conclusions: In tPA‐eligible LVO stroke patients, MSU management did not increase or expedite EVT treatment times as compared to standard EMS management. Future MSU processes should include field CTA with direct admission to cath labs to maximize the early treatment advantage this technology provides.

Keywords

• Ischemic Stroke
• Acute Ischemic Stroke Intervention
• Clinical Trial
• Door To Needle
• Door To Groin Puncture