Abstract 70: Reducing Onset-to-reperfusion Times Through The Implementation Of A Prehospital Large-vessel Occlusion Bypass Protocol: A Real-world Experience

Abstract

Introduction: Time to endovascular treatment (EVT) is a major determinant of patient outcomes for large vessel occlusion (LVO) strokes. Delays in interfacility transfers, however, can limit treatment efficacy. The Cincinnati Stroke Triage Assessment Tool (C-STAT) is a pre-hospital screen used to identify patients suspected of having LVOs. In October 2019, the “Oahu LVO Bypass Protocol” was adopted island-wide for all EMS evaluations. In this protocol, patients with C-STAT+ scores bypassed the nearest local hospital and were diverted to a Comprehensive Stroke Center (CSC). Our study aims to identify how this protocol has impacted onset-to-reperfusion times for patients with LVOs. Methods: A retrospective chart review was performed on all patients receiving EVT from January 1 st , 2017 to February 1 st , 2022. Patients were dichotomized into pre and post bypass groups using October 1 st , 2019 as the implementation date. All non-EMS transfers, posterior circulation strokes, and patients >8 hours from symptom onset were excluded from analysis. We compared the two time epochs using descriptive statistics and an interrupted time-series analysis (ITS). Results: During the 5-year study period, 520 patients received EVT at our institution with an average age of 70.6 and median NIHSS of 19. A total of 115 patients met inclusion for the pre-bypass cohort and 172 patients for the post-bypass cohort. Significant reductions were observed in the median times (pre-bypass(min) [IQR] vs. post-bypass(min) [IQR]) from onset-to-CSC arrival (140[65-214] vs. 68[46-157], p<.001) and onset-to-reperfusion (233[167-310] vs. 189[151-250], p=.005) without significant delay in onset-to-tPA time (100[70-169] vs. 88[67-119], p=.121). The proportion of interfacility EVT transfers also declined from 51% to 17% between the pre and post bypass eras (p<0.001). On ITS analysis, the mean and median level of onset-to-CSC arrival times were significantly reduced by 30% and 51%, respectively. This reduction in treatment time was maintained for a 28-month post-bypass period. Conclusion: Implementation of the Oahu LVO bypass protocol shows significant reduction in onset-to-reperfusion times without delays to tPA administration, while also reducing rates of interfacility transfers.