Simplified selection criteria for patients with longer or unknown time to treatment predict good outcome after mechanical thrombectomy

Objective: To identify simplified selection criteria for mechanical thrombectomy (MT) in longer and unknown time windows.

Methods: Patients with anterior circulation LVO who underwent MT between January 2014 and November 2017 were identified from the local registry, selected if they met current guideline recommendations except for time window (HERMES-like), and divided by time last seen well (LSW <6 hours or >6 hours). The primary endpoint was good outcome (mRS 0–2 at day 90); safety outcomes were 90-day mortality and symptomatic intracranial hemorrhage (sICH).

Results: Of 752 patients, 390 (51.9%) met HERMES-like criteria. Despite baseline differences, patients LSW >6 hours (n=107) did not differ in good outcome (44.9% vs 44.9%), mortality (14% vs 15.2%), or sICH (5.6% vs 6%). Independent predictors of good outcome were age, NIHSS, ASPECTS (OR 1.26), general anesthesia, and successful recanalization — but not treatment time or baseline DWI/CTP.

Conclusion: Patients with proven LVO in unknown and longer time windows may be selected for MT based on ASPECTS and clinical criteria.