Patient selection
This was a single-center retrospective observational analysis of 327 consecutive patients with ACLVO-related AIS treated by MT between January 2016 and August 2022. The hospital's institutional review board approved our study protocol.
Eligible MT-treated subjects met the following inclusion criteria: (1) adult ≥18 years; (2) availability of non-contrast computed tomography (NCCT) imaging done on admission; and (3) proximal anterior circulation occlusion involving internal carotid artery (ICA) or M1/proximal M2 branch of middle cerebral artery (MCA), as shown by computed tomography angiography (CTA) or digital subtraction angiography (DSA). The following were grounds for study exclusion: (1) prior severe stroke, with baseline National Institutes of Health Stroke Scale (NIHSS) score≤8 or baseline modified Rankin Scale (mRS) score≥1; (2) farction on baseline CT; or (3) other brain abnormalities, such as tumors or trauma (shown in Fig. 1).
Data collection
We retrieved baseline patient characteristics (age and sex), medical history (including prior stroke, coronary artery disease, atrial fibrillation/flutter, hypertension, hyperlipidemia, or diabetes mellitus), and lifestyle habits (current/prior tobacco use, alcohol intake), as well as clinical parameters on admission (ie, NIHSS score, diastolic [DBP] and systolic [SBP] blood pressure readings, glycosylated hemoglobin [HbA1c] concentration, D-dimer level, and presence of hyperdense middle cerebral artery sign [HMCAS] or signs of early infarction on NCCT) and intravenous injection of tissue plasminogen activator (tPA) from electronic medical records. Other clinical variables, including trial of ORG 10172 in acute stroke treatment (TOAST) classification, occlusive location, stroke-onset to puncture time, number of device passes, and use of balloon-guided catheter or angioplasty/stenting, were also recorded.
All NCCT studies were performed by Discovery CT 750 HD scanner (GE Healthcare, Chicago, IL, USA) at the following settings: tube voltage, 100 kV; tube current, 120 mA; collimator width, 40mm; field of view, 25cm; layer thickness, 5mm; layer spacing, 5mm. Two neuroradiologists blinded to clinical outcomes separately determined ASPECTS values for each patient. Inconsistencies were resolved by imaging reviews, reaching consensus decisions through discussion.
In ASPECTS determinations, MCA vascular supply has 10 defined territories [1], including seven regions of caudate nucleus and layers below (M1, M2, M3, insula [I], lenticular nucleus[L], caudate nucleus [C], and posterior limb of internal capsule [IC]) and three areas of cerebral cortex above the nucleus(M4, M5, and M6). Maximum score is 10 points, subtracting 1 point for each injured area (shown in Fig. 2).
Clinical outcomes
The primary study endpoint was long-term functional independence, measured by mRS at 90 days. Secondary endpoints were successful vascular reperfusion immediately following MT (ie, modified Thrombolysis in Cerebral Infarction [mTICI] score of 2b or 3); symptomatic intracranial hemorrhage (sICH), indicated by≥4-point decline in NIHSS score or CT evidence of hemorrhage within 24 hours post-MT; and mortality.
Statistical analysis
All computations were driven by standard software (SPSS v22.6; IBM Corp, Armonk, NY, USA). Categorical variables were expressed as frequencies and percentages. The Shapiro-Wilk test was applied to determine normality of distributions. Continuous variables with non-normal distributions were expressed as mean ± standard deviation (SD) or median (interquartile range [IQR]) values. Normally distributed continuous variables were subjected to Student’s t-test, assesssing non-normal variables by Mann-Whitney U test and categorical variables by Fisher’s exact or χ2 test. Multivariate logistic regression analysis served to identify independent predictors of clinical outcomes. Results were presented as odds ratios (ORs) with 95% confidence intervals (CIs), setting significance at p<0.05.