Stroke in patients with large Ischaemic Core: Assessment of Reperfusion therapy Impact on Outcome (SICARIO-LC)

INTERVENTION: SICARIO‐LC will include patients presenting with a baseline perfusion core lesion volume between 70 and 100mL. Patients will be randomized to receive thrombectomy or not. The thrombectomy device and method used will be at the interventionalist's discretion. The thrombolysis decision will be up to the treating physicians’ decision based on current local/regional best evidence guidelines. This will minimize the chances of selection bias as the research team members are not interfering in the clinician’s judgment. However, the research team will control the thrombolysis decision at the randomisation process to avoid any possible imbalances. Two types of standard of care clot retrieval devices used. (brands may vary between countries) 1. Stent retrievers such as Trevo by Stryker, Solitaire by Medtronic. 2. Aspiration catheters such as Penumbra Duration of thrombectomy procedure depends on complexity, approximately 1‐2 hours. Procedure to be initiated within 2 hours of presentation as per protocol and carried out by the neurointerventionalist. CONDITION: Acute Ischaemic stroke; ; Acute Ischaemic stroke Stroke ‐ Ischaemic PRIMARY OUTCOME: For SICARIO‐LC ‐ The proportion of patients with modified Rankin Scale (mRS) 0‐2 (no significant disability) at 3 months. ; ; [3 months post‐randomisation] SECONDARY OUTCOME: SICARIO‐LC ‐ mRS scores at 3 months. ; ; [3 months post randomisation] SICARIO‐LC ‐ overall health assessed by PROMS‐10 ; ; [3 months & also 12 months post randomisation for participants enrolled in Australia & New Zealand..] SICARIO‐LC ‐ Proportion of patients with mRS score 0‐2 at 12 months (for those patients enrolled in Australia and New Zealand). ; ; [3 months & also 12 months post randomisation for participants enrolled in Australia & New Zealand.] SICARIO‐LC ‐ Proportion of patients with mRS score 0‐3 at 12 months (for those patients enrolled in Australia and New Zealand). ; ; [3 months & also 12 months post randomisation for participants enrolled in Australia & New Zealand.] SICARIO‐LC ‐ Proportion of patients with mRS score 0‐3 at 3 months. ; ; [3 months post randomisation] SICARIO‐LC ‐ Proportion of patients with mRS score 0‐4 at 12 months (for those patients enrolled in Australia and New Zealand). ; ; [3 months & also 12 months post randomisation for participants enrolled in Australia & New Zealand..] SICARIO‐LC ‐ Proportion of patients with mRS score 0‐4 at 3 months. ; ; [3 months post randomisation] SICARIO‐LC ‐ quality of life assessed by EQ‐5D ; ; [3 months & also 12 months post randomisation for participants enrolled in Australia & New Zealand..] INCLUSION CRITERIA: • Patients presenting with acute hemispheric ischemic stroke with onset (or the time last known to be well) within 24 hours. • Presence of a baseline ischemic core of 70‐100 mL on CT perfusion imaging or diffusion‐perfusion MRI processed with automated perfusion volumetric analysis (MIStar ‐ Apollo Medical Imaging specified as the preferred software for the trial aiming to reduce volume estimation variability). • Patient’s age is 18 years or above • Premorbid modified Rankin Scale score 0 to 2. • Presence of a large vessel occlusion on CTA or MRA. Large vessel occlusion will be defined as a ‘potentially retrievable’ thrombus at one or more of the following sites: intracranial internal carotid (ICA), middle cerebral artery (MCA) first segment (M1) or combination of an extracranial segment of ICA and an intracranial occlusion (terminal ICA or MCA) ‐tandem occlusion‐. • Onset of acute imaging to groin puncture (in the patients randomized to thro