To evaluate the association of infarct volume, collateral circulation, and reperfusion grade with 90-day outcome after mechanical thrombectomy (MT) in acute ischemic stroke, and identify an infarct-volume threshold predicting poor prognosis.

Mechanical thrombectomy has transformed stroke care, yet outcomes vary. Imaging markers such as infarct size, collateral status, and reperfusion quality may refine prognosis and guide patient selection.

This prospective study included 41 adults with acute ischemic stroke who underwent MT within 24 hours of onset. Infarct volume was measured on diffusion-weighted MRI using the ABC/2 method. Collaterals were graded by ASITN/SIR for anterior and BATMAN for posterior circulation. Reperfusion was assessed by modified Thrombolysis in Cerebral Infarction (mTICI) score. Functional outcome at 90 days was classified as good (modified Rankin Scale ≤ 2) or poor (≥ 3). Logistic regression identified independent predictors, and ROC analysis determined the infarct-volume cutoff linked with poor outcome.

Mean age was 68.2 ± 9.7 years; 51 % were men. Good reperfusion (mTICI 2b–3) occurred in 92.7 % and good collaterals in 68.3 %. At 90 days, 51.2 % achieved independence. Larger infarct volume (39.2 ± 19.3 cc vs 81.6 ± 29.6 cc, p < 0.001) and symptomatic intracranial hemorrhage (34.1 %, p < 0.001) were linked to poor outcomes, while collateral grade and time metrics were not. Multivariable analysis found infarct volume (OR 0.31, 95 % CI 0.15–0.67, p = 0.002), mTICI grade (OR 15.8, p = 0.04), and sICH (OR 0.13, p = 0.006) as independent predictors. ROC analysis for anterior circulation showed AUC 0.91, with 50 cc the optimal cutoff (sensitivity 88 %, specificity 85 %).

Infarct volume, reperfusion quality, and symptomatic hemorrhage independently influence 90-day outcome after MT. An infarct volume > 50 cc in anterior-circulation strokes strongly predicts poor recovery highlighting the prognostic value of early volumetric imaging.