ATLAS
(2026)Objective
To synthesize evidence from recent trials of endovascular thrombectomy in patients with large-core ischaemic stroke presenting up to 24 h after onset, and to estimate treatment benefit within clinical and imaging subgroups.
Study Summary
• EVT reduced 90-day mortality (31.1% vs 37.3%; aRR 0.82, 95% CI 0.70-0.97, p=0.022)
• No significant difference in symptomatic intracranial haemorrhage (1.1% vs 1.0%; risk difference -0.17 percentage points, 95% CI -1.01 to 0.67, p=0.69)
• No difference in neurological worsening (22.0% vs 17.9%; aRR 1.19, 95% CI 0.87-1.62, p=0.27)
• NNT 4.2 (95% CI 3.3-5.8) to improve ≥1 mRS point; NNT 8.6 for functional independence; NNT 14.6 for reduced mortality
• Benefit consistent across ASPECTS, perfusion mismatch, age, NIHSS, and occlusion site subgroups; uncertain for ischaemic core ≥150 mL beyond 6 h
Intervention
Endovascular thrombectomy versus best medical management in patients with large-core ischaemic stroke (ASPECTS ≤5 or estimated ischaemic core ≥50 mL) presenting within 24 h of onset.
Inclusion Criteria
Adults with acute ischaemic stroke due to anterior circulation large-vessel occlusion, large-core ischaemic stroke (ASPECTS ≤5 on non-contrast CT or MR diffusion, or estimated ischaemic core ≥50 mL on CT perfusion or MR diffusion), within 24 h of last-known-well, randomised to EVT or best medical care.
Study Design
Arms: Endovascular thrombectomy (n=944) vs Medical management (n=942)
Patients per Arm: EVT n=944; Medical management n=942
Outcome
• Mortality at 90 days reduced with EVT: 31.1% vs 37.3% (aRR 0.82, 95% CI 0.70-0.97, p=0.022)
• Symptomatic intracranial haemorrhage: 1.1% vs 1.0% (risk difference -0.17 pp, 95% CI -1.01 to 0.67, p=0.69)
• Neurological worsening at 24-48 h: 22.0% vs 17.9% (aRR 1.19, 95% CI 0.87-1.62, p=0.27)
• Successful reperfusion (eTICI 2b-3) achieved in 82.7% (95% CI 80.2-85.0) of EVT patients
• Benefit sustained across ASPECTS and ischaemic core strata up to 150 mL; limited evidence for core ≥150 mL beyond 6 h
Bottom Line
Endovascular thrombectomy improves 90-day functional outcomes and reduces mortality vs medical management in patients with large-core ischaemic stroke presenting within 24 h, without an increase in symptomatic intracranial haemorrhage. Benefit was sustained across ASPECTS and ischaemic core strata up to 150 mL; evidence remains limited for core volumes ≥150 mL beyond 6 h.
Major Points
- Individual patient data meta-analysis of 6 RCTs, 1886 patients with large-core ischaemic stroke (ASPECTS ≤5 or ischaemic core ≥50 mL) within 24 h
- EVT improved 90-day mRS distribution: aGenOR 1.63 (95% CI 1.42-1.88, p<0.0001)
- Reduced 90-day mortality: 31.1% (EVT) vs 37.3% (medical); aRR 0.82 (95% CI 0.70-0.97, p=0.022)
- No increase in symptomatic intracranial haemorrhage: 1.1% vs 1.0% (risk difference -0.17 pp, p=0.69)
- No significant difference in early neurological worsening (24-48 h): 22.0% vs 17.9% (aRR 1.19, p=0.27)
- NNT 4.2 to improve ≥1 mRS point; NNT 8.6 for functional independence (mRS 0-2); NNT 5.7 for independent ambulation (mRS 0-3); NNT 14.6 for reduced mortality
- Successful reperfusion (eTICI 2b-3) achieved in 82.7% of EVT-treated patients
- Benefit consistent across age, NIHSS, occlusion site (ICA vs MCA), hemisphere, time window, ASPECTS strata (0-2, 3, 4, 5, 6-10), and presence or absence of perfusion mismatch
- Benefit sustained for ischaemic core volumes up to 150 mL; for core ≥150 mL, point estimates favoured EVT (especially 0-6 h) but wide CIs limited interpretation
- Central imaging core laboratory readjudicated ASPECTS, ischaemic core volume, perfusion mismatch, and haemorrhagic transformation across all trials
Study Design
- Study Type
- Systematic review and individual patient data meta-analysis with central imaging adjudication
- Randomization
- Yes
- Blinding
- Central imaging adjudicators masked to treatment group, source trial, and original core laboratory ASPECTS readings
- Sample Size
- 1886
- Follow-up
- 90 days (primary outcome); 1-year outcomes planned in dedicated analysis
Primary Outcome
Definition: Distribution of modified Rankin Scale (mRS) scores at 90 days (mRS scores 5 and 6 merged into one category)
| Control | Intervention | HR/OR | P-value |
|---|---|---|---|
| Median mRS 5 (IQR 4-6), n=931 | Median mRS 4 (IQR 3-6), n=940 | 1.63 (1.42-1.88) | <0.0001 |
Limitations & Criticisms
- Wide 95% CIs for ischaemic core volume ≥150 mL subgroup limit interpretation, particularly beyond 6 h
- Some concerns for risk of bias for secondary outcome of neurological worsening due to missing data in two trials
- Perfusion mismatch status available for only 56.1% of patients
- 1-year outcomes not uniformly collected; planned in dedicated analysis
- Heterogeneity in original trial eligibility criteria (different imaging modalities, time windows, ASPECTS/core volume thresholds)
- 95% CIs for secondary outcomes and subgroup analyses not adjusted for multiple comparisons
Citation
Sarraj A, et al. Endovascular thrombectomy for patients with large-core ischaemic stroke presenting up to 24 h after onset (ATLAS): a systematic review and individual patient data meta-analysis with central imaging adjudication. The Lancet. Available online 7 May 2026.