Brain frailty assessed by pre-treatment MRI to evaluate its impact on 3month functional outcomes in anterior circulation AIS patients undergoing MT.

We retrospectively analyzed 264 patients with anterior circulation large vessel occlusion (LVO) who underwent mechanical thrombectomy (MT). Brain frailty was operationalized as a latent construct comprising global cortical atrophy, Fazekas scores of periventricular and deep white matter, and the presence of old cortical infarctions and lacunes. Structural equation modeling (SEM) was performed to evaluate the direct and indirect effects of age on 3-month functional outcome, defined by the modified Rankin Scale (mRS), with brain frailty specified as the mediating factor.

Brain frailty was directly associated with poor 3-month outcome (β = 0.36, p = 0.003). Age was positively associated with brain frailty (β = 0.17, p < 0.001) and showed a significant indirect effect on poor outcome through brain frailty (β = 0.054, 95% CI 0.028–0.080, p < 0.001). The direct effect of age on outcome was not significant, supporting a full mediation model. Additional analyses showed that higher NIHSS, severe hypoperfusion intensity ratio, and failed reperfusion were independently related to poor outcome. Logistic regression confirmed that brain frailty was significantly associated with poor functional outcome (OR = 2.53, 95% CI 1.14–5.63, p = 0.023).

Brain frailty on pre-treatment MRI independently predicted poor 3-month outcome after mechanical thrombectomy for anterior circulation AIS, providing prognostic value beyond reperfusion status and age. Considering brain frailty may improve outcome prediction in clinical practice.