Functional outcomes following mechanical thrombectomy beyond 6 hours after acute ischaemic stroke

Mechanical thrombectomy (MT) within 6 hours is the standard treatment for large vessel occlusion stroke. However, the benefit-to-risk ratio of MT becomes increasingly unfavourable in the extended 6- to 24-hour window; current guidelines recommend cerebral perfusion studies (CPS) for patient selection. Although recent trials of extended-window MT have shown promising results, challenges may arise in real-world implementation where CPS are not readily available. This single-centre retrospective review included patients who underwent extended-window MT with or without prior CPS in Hong Kong.

This study included 480 patients who underwent MT at Queen Mary Hospital between January 2019 and January 2025. Primary outcomes were 3-month modified Rankin Scale, door-to-groin puncture time, recanalisation rate, procedural complications and mortality. Secondary outcomes included differences in 3-month functional status between patients who underwent MT with or without prior CPS.

Among the 51 patients who underwent extended-window MT, 37 (72.5%) had anterior circulation stroke. The overall complication rate was 7.8%. Cerebral perfusion studies were performed to guide selection in 15 patients (40.5%) with anterior circulation strokes and were associated with a significantly higher rate of functional independence at 3 months compared with selection based on clinical judgement alone (66.7% vs 27.3%; P=0.018). Use of CPS was also associated with a longer door-to-puncture time (167 vs 89.5 min; P<0.001).

Cerebral perfusion studies improve patient selection for extended-window MT. Favourable functional outcomes were achieved in a substantial proportion of patients selected on the basis of clinical criteria alone. The study findings provide evidence supporting clinical service development to facilitate CPS adoption and extended-window MT in Hong Kong.