We aimed to compare the relative neutrophil, lymphocyte, and monocyte counts between fast and slow progressor phenotypes of anterior circulation large vessel occlusion (ACLVO) stroke.

The determinants of individual fast to slow progression of infarct growth due to ACLVO are poorly understood. Peripheral white blood cell (WBC) changes have been associated with stroke severity, but differences in WBC subtypes between fast and slow progressors of ACLVO stroke are unknown.

Single-center retrospective study of patients with occlusions of the MCA or ICA from 2014-2017. Baseline CTP or MRI were obtained within 24 hours of stroke onset. Fast progressors (ischemic core > 70ml, 0-6 hours) and slow progressors (</= 30ml, 6-24hours) were identified. Lymphocyte, neutrophil, monocyte percentages (relative to total WBC number) were compared in three groups: fast vs. non-fast progressors (0-6 hours), slow vs. non-slow progressors (6-24 hours), fast vs. slow progressors. Mann-Whitney test was used for univariate comparisons. Multivariate logistic regression tested the independent association of WBC subtypes with progressor status.

There were 185 patients with mean age of 71, median NIHSS 17, and median WBC of 9.9x10³ cells. Fast progressors had increased neutrophil percentage (79 vs. 73%, p=0.04) and decreased lymphocyte percentage (9 vs. 15%, p=0.06) relative to non-fast progressors. Slow progressors had significantly decreased monocyte percentage relative to non-slow progressors (6 vs. 8%, p=0.01). After adjusting for age, NIHSS, and sex on multivariate regression, only the monocyte percentage (OR 0.68, 95%Cl 0.53-0.88) was independently associated with slow progressor status.

Peripheral WBC subtypes differ between fast and slow progressor phenotypes of ACLVO stroke. Point of care WBC differential count may be help predict early infarct growth rate in the emergency setting.