PDF: BAOCHE
(2022)Objective
To assess whether endovascular thrombectomy plus medical therapy improves outcomes compared to medical therapy alone in patients with basilar-artery occlusion stroke presenting 6 to 24 hours after symptom onset.
Study Summary
• Trial was stopped early due to efficacy.
• Symptomatic intracranial hemorrhage and procedural complications were more frequent with thrombectomy.
Intervention
Multicenter, open-label, randomized controlled trial conducted in China. Patients were randomized to receive either thrombectomy plus standard medical therapy or standard therapy alone. Imaging eligibility required no large infarcts (PC-ASPECTS ≥6). Thrombectomy used Solitaire device within 6–24 hours of last known well.
Inclusion Criteria
Adults aged 18–80 with NIHSS ≥6 and basilar-artery or bilateral vertebral occlusion, presenting 6–24 hours from symptom onset. Required small infarct burden and good pre-stroke function (mRS 0–1).
Study Design
Arms: Thrombectomy + Medical Therapy vs. Medical Therapy Alone
Patients per Arm: Thrombectomy: 110; Control: 107
Outcome
• Functional independence (mRS 0–2): 39% vs. 14%; adjusted rate ratio 2.75 (95% CI, 1.65–4.56)
• Revascularization: 88% successful (TICI ≥2b)
• Symptomatic ICH: 6% vs. 1%
• Mortality at 90 days: 31% (thrombectomy) vs. 42% (control); adjusted RR 0.75 (95% CI, 0.54–1.04)
Bottom Line
Thrombectomy plus medical therapy resulted in good functional status (mRS 0-3) at 90 days in 46% of patients vs. 24% with medical therapy alone (adjusted rate ratio 1.81; 95% CI, 1.26-2.60; P<0.001; NNT ~5). The trial was stopped early for efficacy at a prespecified interim analysis after 218 of planned 318 patients. However, thrombectomy was associated with more procedural complications (11%) and a numerically higher rate of symptomatic intracranial hemorrhage (6% vs. 1%).
Major Points
- Primary outcome positive: mRS 0-3 at 90 days was 46% (thrombectomy) vs. 24% (control), adjusted RR 1.81 (95% CI 1.26-2.60; P<0.001), NNT ~5.
- Original primary outcome (mRS 0-4) was null: 55% vs. 43% (adjusted RR 1.21; 95% CI 0.95-1.54) — primary endpoint was changed from mRS 0-4 to mRS 0-3 mid-trial (before unblinding) based on external data from BEST and BASICS.
- Functional independence (mRS 0-2) nearly tripled: 39% thrombectomy vs. 14% control (adjusted RR 2.75; 95% CI 1.65-4.56).
- Ordinal mRS shift favored thrombectomy: common odds ratio 2.64 (95% CI 1.54-4.50).
- Mortality was not significantly different: 31% thrombectomy vs. 42% control (adjusted RR 0.75; 95% CI 0.54-1.04).
- High reperfusion rate: mTICI 2b/3 achieved in 88% of thrombectomy patients; basilar-artery patency at 24 hours was 92% vs. 19%.
- Extended time window validated: benefit consistent in 6-12h window (RR 1.89) and >12-24h window (RR 1.71).
- sICH (SITS-MOST) was 6% vs. 1%; sICH (ECASS II) was 9% vs. 2%. NNH for sICH ~20.
- Procedural complications in 11%: vessel dissection (4%), vessel perforation (3%), distal embolization (5%). Rescue angioplasty/stenting needed in 55% of patients, reflecting high atherosclerotic burden.
- Trial stopped early after prespecified interim analysis of 212 patients crossed the O'Brien-Fleming boundary (P<0.012 threshold).
Study Design
- Study Type
- Investigator-initiated, multicenter, open-label, randomized, controlled trial with blinded outcome evaluation (PROBE design)
- Randomization
- Yes
- Blinding
- Open-label treatment; blinded outcome assessment by local assessors unaware of treatment plus central assessors via video/audio recordings
- Sample Size
- 218
- Follow-up
- 90 days (primary); also 6 and 12 months for EQ-5D-3L
- Centers
- 30
- Countries
- China
Primary Outcome
Definition: mRS 0-3 at 90 days
| Control | Intervention | HR/OR | P-value |
|---|---|---|---|
| 26/107 (24%) | 51/110 (46%) | - (1.26-2.60) | <0.001 |
Limitations & Criticisms
- Primary outcome changed mid-trial from mRS 0-4 to mRS 0-3 (though before unblinding, based on external BEST/BASICS data). Original primary (mRS 0-4) was null.
- Open-label design, though outcome assessment was blinded.
- Limited to Han Chinese population — generalizability uncertain, especially for embolic vs atherothrombotic etiology.
- 101 of 319 excluded patients underwent endovascular therapy outside the trial — selection bias.
- Low IV thrombolysis rate (14-21%) — patients had to pay for the drug; less than two-thirds arriving within 4.5h received it.
- Early stopping for efficacy after 218 of 318 planned patients may overestimate treatment effect.
- Original primary outcome (mRS 0-4) had CI crossing 1.0 (RR 1.21, 0.95-1.54).
- Rescue intracranial angioplasty/stenting was needed in 55%, reflecting predominantly atherosclerotic etiology that may differ from Western populations.
Citation
N Engl J Med 2022;387:1373-84.