Abstract 3: Early Recanalization of Large Vessel Occlusions by tPA on the Mobile Stroke Unit

Abstract

Introduction: The benefit of intravenous tPA in acute ischemic stroke patients with large vessel occlusions (LVOs) is limited but time dependent. We evaluated pre-hospital treatment with tPA on the Mobile Stroke Unit (MSU) to explore the recanalization rate in patients with LVOs and its effect on clinical improvement upon ED arrival. Methods: Prospectively derived data were analyzed from patients on the Houston MSU who were treated with tPA and had LVOs identified by hyperdense artery on MSU CT or arterial occlusion on MSU CTA. The primary outcome was early recanalization, categorized as resolution of LVO on repeat vascular imaging in the ED or on emergent angiography versus no recanalization. Secondary outcome was change in baseline NIHSS at 24 hours. Differences in NIHSS were evaluated using Wilcoxon rank sum test with continuity correction. Results: Seventy-one patients received tPA and had proximal LVOs both in the anterior and posterior circulation. Eleven had recanalization on CTA upon ED arrival (15.5%), while 7 had recanalization on emergent angiography (9.9%). The total early recanalization rate with tPA was 25.4%. Forty-seven patients with persistent LVOs on ED arrival (66.2%) underwent endovascular thrombectomy (EVT). Time from symptom onset (last known normal) to tPA bolus did not differ significantly between the early recanalization vs non-early recanalization groups (64.5 minutes [IQR 43.0-78.5] vs 64.0 minutes [52.5-92.0]; p = 0.41). Early recanalization resulted in greater improvement in baseline to ED arrival NIHSS (median NIHSS change 4.0 [0-11.8] vs 0 [0-3.5]; p = 0.01). There were no differences in ED arrival to 24 hour NIHSS between the early recanalization versus non-early recanalization groups irrespective of EVT. Conclusions: Recanalization by ED arrival occurs in 25% of LVO patients with tPA treatment on a MSU and was associated with early clinical improvement. Subsequent EVT did not “make up” for the clinical benefit of early recanalization.