# Influence of interhospital transfer on endovascular thrombectomy outcome in acute ischemic stroke patients: an analysis of the TREAT-AIS registry

## TL;DR

This study examines how arriving directly to a stroke center versus being transferred affects outcomes for stroke patients undergoing a specific treatment.

## Contribution

The study reveals that transfer patients may benefit more from treatment if it occurs later than six hours.

## Key findings

- Direct arrival to a stroke center was linked to better outcomes when treatment began within six hours.
- Transfer patients had higher odds of a good outcome when treatment occurred six hours or later.
- The relationship between arrival pathway and outcome depends on treatment timing.

## Abstract

The outcome of patients undergoing endovascular thrombectomy (EVT) for large vessel occlusion in a comprehensive stroke center (CSC) is affected by the onset-to-treatment time. Whether the pathway to CSC arrival (direct vs. interhospital transfer) is thus associated with EVT outcomes among such patients is unknown.

Using the Taiwan Registry of Endovascular Thrombectomy for AIS registry, patients ≥20 years of age and receiving EVT for AIS within 24 h of onset between January 2019 and December 2022 were included. Patients were categorized according to CSC arrival pathway into direct arrival and transfer groups. The primary outcome was 3-month functional independence, defined as a modified Rankin Scale (mRS) of 0–2.

Of the1830 patients included, 79% arrived at a CSC directly and 21% via transfer. More patients in the direct arrival than the transfer group achieved a 3-month mRS of 0–2. A significant interaction was found between onset-to-puncture (OTP) time and arrival pathway for achieving 3-month mRS 0–2 (p
interaction = 0.017). Arrival by transfer was associated with reduced odds of achieving mRS 0–2 when OTP time was < 6 h (aOR, 0.55), but with increased odds when OTP was ≥6 h (aOR, 1.95).

Direct arrival was associated with improved outcomes if OTP < 6 h. Patients who arrive via transfer may still benefit substantially from EVT during the later treatment window. Further study is warranted to examine the predictors of favorable post-EVT outcomes within a 24-h window to facilitate timely treatment.