Impact of Helicopter Transfer on Recanalization and Outcomes in Anterior Large Vessel Occlusion Strokes

Abstract

Background: For patients with acute ischemic stroke due to a large vessel occlusion admitted in primary stroke centers, helicopter transfer to comprehensive stroke centers is often used to expedite access to mechanical thrombectomy. Some studies have suggested that vibrations generated during helicopter transport might enhance intravenous thrombolysis (IVT) efficacy. We aimed to evaluate the impact of helicopter transfer, compared with ground transportation, on interhospital recanalization and functional outcomes.

Methods: We conducted a retrospective analysis of 2 prospectively collected cohorts of anterior circulation acute ischemic stroke due to a large vessel occlusion patients transferred to 2 comprehensive stroke centers (Stanford, CA, November 2019 to January 2023, and Montpellier, France, January 2015 to January 2017) for mechanical thrombectomy consideration with arterial imaging both at the primary stroke center and on comprehensive stroke center arrival. The primary outcome was interhospital recanalization, determined by comparison of the baseline and posttransfer arterial imaging and defined as revised arterial occlusive lesion scores of 2b to 3. The association between transportation mode (helicopter versus ground) and interhospital recanalization was studied in logistic regression analysis, adjusting for pretransfer IVT use, occlusion site, and transfer duration.

Results: Among 520 included patients, 315 (61%) were transferred by helicopter and 259 (50%) received IVT before transfer. Interhospital recanalization rates were similar between helicopter and ground transfers in both the overall cohort (23% versus 19%; P=0.30) and the IVT subgroup (36% versus 33%; P=0.61). Adjusted analyses confirmed no association between helicopter transport and interhospital recanalization (adjusted odds ratio, 1.23 [95% CI, 0.72-2.11]; P=0.44). Favorable 3-month functional outcome (modified Rankin Scale score, 0-2) rates were also similar between helicopter and ground transfers in both unadjusted (35% versus 40%; P=0.29) and adjusted analyses (adjusted odds ratio, 1.12 [95% CI, 0.67-1.88]; P=0.67).

Conclusions: In this multicenter observational cohort study, helicopter transfer was not associated with improved interhospital recanalization or favorable functional outcomes compared with ground transport. These findings do not support the hypothesis that vibrations during helicopter transport enhance IVT efficacy.

Keywords: infarction, middle cerebral artery; middle cerebral artery; reperfusion; stroke; thrombectomy.