Prognostic significance of peripheral immunity after thrombectomy in acute ischemic stroke: a retrospective study stratified by early post-EVT leukocyte count.

BACKGROUND: The prognostic relevance of early peripheral immune profiles after successful endovascular thrombectomy (EVT) remains incompletely characterized. We evaluated whether associations between lymphocyte-subset percentages and 90-day functional outcome differed according to early post-EVT white blood cell (WBC) count. MATERIALS AND METHODS: This retrospective single-center study included acute anterior-circulation large-vessel occlusion who achieved successful reperfusion (mTICI 2b or 3) after EVT between January 2021 and December 2023. Blood samples obtained within 24 hours after EVT were classified as normal WBC (4.0-10.0 ×10^9/L) or elevated WBC (>10.0 ×10^9/L). The primary outcome was unfavorable 90-day functional status (mRS 3-6). Prespecified multivariable logistic models adjusted for age, sex, admission NIHSS, ASPECTS, ICA versus MCA occlusion, collateral status, and mTICI grade. Interaction, nonlinear, and sensitivity analyses were also performed. RESULTS: A total of 334 patients met the eligibility criteria; after excluding one patient without a valid 90-day mRS assessment, 333 patients were included in the primary outcome analysis, including 205 (61.6%) in the normal-WBC group and 128 (38.4%) in the elevated-WBC group. In the normal-WBC group, lower CD19+ B-cell percentage (adjusted odds ratio [aOR] 0.918, 95% CI 0.864-0.976; P = 0.006) and higher NLR (aOR 1.170, 95% CI 1.043-1.311; P = 0.007) were associated with unfavorable outcome. In the elevated-WBC group, lower CD3+ T-cell percentage (aOR 0.960, 95% CI 0.926-0.995; P = 0.026) and lower CD8+ T-cell percentage (aOR 0.943, 95% CI 0.896-0.992; P = 0.024) were associated with unfavorable outcome. Biomarker-by-WBC interactions were significant for CD19, NLR, CD3, and CD8. Addition of these biomarkers numerically increased AUCs, but paired DeLong comparisons were not statistically significant. CONCLUSION: Early post-EVT WBC count modified the associations between selected peripheral immune-cell percentages and 90-day functional outcome. These exploratory findings require prospective validation. TRIAL REGISTRATION: www.chictr.org.cn, identifier ChiCTR2300070650.