Prehospital Stroke Triage to Route Patients Directly to a Thrombectomy Center: New York City First-Year Experience

New York City Emergency Medical Services implemented a prehospital triage protocol using a modified Speech-Los Angeles Motor Scale to identify patients with large-vessel occlusion. Patients with Speech-Los Angeles Motor Scale ≥4 and last known well within 5 hours were routed to the nearest thrombectomy-capable stroke center. Our aim was to describe the Speech-Los Angeles Motor Scale Triage Positive (STP) cohort and compare to a cohort that ultimately underwent endovascular thrombectomy (EVT) but were missed by the protocol (not triaged as Speech-Los Angeles Motor Scale positive [NSTP]).

A prospectively collected database identified patients arriving within 5 hours from last known well between April 2019 and March 2020. STP patients (N=145) were assessed for medical history, acute stroke time metrics, and clinical accuracy. NSTP (N=65) was subdivided into those who arrived directly to a thrombectomy-capable stroke center (direct NSTP, N=30), and those transferred to a thrombectomy-capable stroke center (transferred NSTP, N=35). Comparisons were made between the cohorts that underwent EVT.

In the STP cohort, stroke was diagnosed in 110 of 145 (75.9%) patients: 31 hemorrhagic, 79 ischemic. There were 45 patients (31.0%) with large vessel occlusion and 34 (23.4%) underwent EVT. STP and NSTP subgroups had no difference in first medical contact-to-intravenous thrombolysis (≈90 minutes) despite STP patients taking 5 minutes longer to arrive. Ambulance travel times were similar (11 minutes). First medical contact-to-arterial access was similar in STP (137.9 minutes) and direct NSTP (137.9 minutes) groups but significantly shorter against transferred NSTP (252.1 minutes; P<0.01).

Through the protocol, a high percentage of identified patients with large-vessel occlusion undergo EVT with no sacrifice to intravenous thrombolysis. The increased ambulance travel time has minimal effect. As more than half the NSTP cohort required transfer for EVT, these patients would have reaped the greatest benefit. Appropriate implementation that maintains the score specificity would prevent patients with high large-vessel occlusion likelihood from delayed thrombectomy.