Introduction Symptomatic intracranial hemorrhage after MT has a reported incidence rate of up to 16% in previous studies and can amplify the risk of poor clinical outcome.

Aim of Study The aim of our study was to find predictors of parenchymal hematoma (PH) and clinical outcome after mechanical thrombectomy (MT) in patients with large vessel occlusion (LVO) and baseline large infarct.

Methods The databases of 16 stroke centers were retrospectively screened for patients with anterior circulation LVO and baseline ASPECTS ≤5 that received MT. Outcome measures were occurrence of PH type 2 and any type of PH after MT, and the 90-day mRS score of 0-3 and 0-2.

Results In total, 408 patients were available for analysis. A higher number of passes in the second technique was predictive of PH type 2 (odds ratio (OR) - 3.204, 95% confidence interval (CI) 1.140 to 9.005), whereas procedure conducted under general anesthesia was associated with lower risk (OR 0.127, 95% CI 0.002 to 0.808). The modified thrombolysis in cerebral infarction grade 2c-3 was associated with the mRS score 0-3 (OR 3.373, 95% CI 1.891 to 6.017), whereas occurrence of PH type 2 was predictive of unfavorable outcome (OR 0.221, 95% CI 0.063 to 0.773). Similar results were found for the mRS score 0-2 outcome measure.

Conclusion In patients with large ischemic core, a higher number of passes during MT and procedure not conducted under general anesthesia are associated with increased rate of PH type 2, that negatively impact the clinical outcome.