← Back

BAOCHE

Trial of Thrombectomy 6 to 24 Hours after Stroke Due to Basilar-Artery Occlusion

Share Share Copied! Compare

Year of Publication: 2022

Authors: Tudor G. Jovin, Chuanhui Li, Longfei Wu, ..., for the BAOCHE Investigators

Journal: The New England Journal of Medicine

Citation: N Engl J Med 2022;387:1373-84.

Link: https://www.nejm.org/doi/full/10.1056/NEJMoa2207576

PDF: https://www.nejm.org/doi/pdf/10.1056/NEJ...ticleTools=true

Clinical Question

In patients with acute ischemic stroke due to basilar-artery occlusion presenting 6 to 24 hours after symptom onset, does endovascular thrombectomy plus standard medical therapy improve functional outcomes compared with standard medical therapy alone?

Study Overview

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

Thrombectomy significantly improved good functional outcome (mRS 0–3) at 90 days.
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.

Patients per Arm

Thrombectomy: 110; Control: 107

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 of the first 212 enrolled patients who had completed 90-day follow-up (218 total underwent randomization; planned enrollment was 318). 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 rate ratio 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 rate ratio 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 rate ratio 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 risk ratio 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 (adjusted rate ratio 1.89) and >12-24h window (adjusted rate ratio 1.71).
sICH (SITS-MOST) was 6% vs. 1% (risk ratio 5.18); sICH (ECASS II) was 9% vs. 2% (risk ratio 3.88). 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 the first 212 enrolled patients (who had completed 90-day follow-up) crossed the O'Brien-Fleming boundary (P<0.012 threshold).

      

Design

Study Type: Investigator-initiated, multicenter, open-label, randomized, controlled trial with blinded outcome evaluation (PROBE design)

Randomization: 1

Blinding: Open-label treatment; blinded outcome assessment by local assessors unaware of treatment plus central assessors via video/audio recordings

Enrollment Period: August 2016 to June 2021

Follow-up Duration: 90 days (primary); also 6 and 12 months for EQ-5D-3L

Centers: 30

Countries: China

Sample Size: 218

Analysis: Intention-to-treat (ITT); also per-protocol (102 vs 100) and as-treated (113 vs 104). Stratified by age (≤70 or >70), time window (6-12h or >12-24h), baseline NIHSS (6-20 or >20).

Inclusion Criteria

Age 18 to 80 years.
Occlusion of the basilar artery or intracranial segments of both vertebral arteries.
Treatable within 6 to 24 hours after symptom onset (last known well, excluding isolated vertigo).
Pre-stroke modified Rankin Scale score of 0 or 1.
NIHSS score ≥10 at presentation (amended to ≥6 after first 61 patients due to slow recruitment).
PC-ASPECTS ≥6 on CT, CTA source images, or DWI-MRI.
Pons-Midbrain Index ≤2 (1 point = infarction <50% one side; 2 points = ≥50% one side).

Exclusion Criteria

Evidence of recent intracranial hemorrhage on imaging.
Large posterior circulation infarct: PC-ASPECTS <6.
Large brainstem infarct: Pons-Midbrain Index >2.
Additional criteria detailed in Supplementary Table S1.

Baseline Characteristics

Characteristic	Thrombectomy (N=110)	Control (N=107)
Age (mean±SD)	64.2±9.6	63.7±9.8
Male sex	80 (73%)	79 (74%)
Atrial fibrillation	14 (13%)	13 (12%)
Diabetes mellitus	30 (27%)	29 (27%)
Hypertension	90/110 (82%)	79/106 (75%)
Pre-stroke mRS 0	85 (77%)	89 (83%)
NIHSS median (IQR)	20 (15-29)	19 (12-30)
NIHSS 6-20	66 (60%)	61 (57%)
NIHSS >20	44 (40%)	46 (43%)
Median SBP (IQR)	157 (138-175) mmHg	152 (138-166) mmHg
IV thrombolysis received	15 (14%)	23 (21%)
Median PC-ASPECTS (IQR)	8 (7-10)	8 (7-10)
Median Pons-Midbrain Index (IQR)	1 (0-2)	1 (0-2)
Occlusion site — Proximal basilar	53/107 (50%)	45/105 (43%)
Occlusion site — Middle basilar	40/107 (37%)	37/105 (35%)
Occlusion site — Distal basilar	13/107 (12%)	23/105 (22%)
Time window 6-12h	64 (58%)	71 (66%)
Time window >12-24h	46 (42%)	36 (34%)
Median onset-to-randomization (IQR)	664 (512-861) min	662 (492-838) min
Median onset-to-revascularization (IQR)	790 (626-1000) min
General anesthesia used	72 (65%)

Arms

Field	Thrombectomy + Medical Therapy	Control
Intervention	Endovascular thrombectomy using Solitaire device (Medtronic) plus standard medical care per Chinese guidelines. Rescue balloon angioplasty or stenting of vertebral/basilar artery permitted. Intracranial angioplasty/stenting after failed thrombectomy performed in 60 patients (55%). General anesthesia in 65%. IV alteplase permitted if within 4.5h (14% received it). Admitted to acute stroke unit or neurologic ICU.	Standard acute ischemic stroke management per Chinese guidelines. Admitted to acute stroke unit or neurologic ICU. IV alteplase if within 4.5h (21% received it). 4 patients (3.7%) crossed over to endovascular treatment.
Duration	Single procedure + 90 days follow-up	90 days follow-up

Outcomes

Outcome	Type	Control	Intervention	HR / OR / RR	P-value
mRS 0-3 at 90 days	Primary	26/107 (24%)	51/110 (46%)	5	<0.001
Ordinal mRS shift at 90 days	Secondary	—	—	Common odds ratio 2.64
mRS 0-2 at 90 days	Secondary	15/107 (14%)	43/110 (39%)	Adjusted rate ratio 2.75
mRS 0-4 at 90 days (original primary)	Secondary	46/107 (43%)	61/110 (55%)	Adjusted rate ratio 1.21
Dramatic neurologic improvement at 24h (≥8pt NIHSS drop or 0-2)	Secondary	9/94 (10%)	25/101 (25%)	Adjusted rate ratio 2.50
Barthel Index 95-100 at 90 days	Secondary	10/56 (18%)	26/73 (36%)	Adjusted rate ratio 2.20
Basilar-artery patency at 24h	Secondary	15/77 (19%)	76/83 (92%)	Adjusted rate ratio 4.53
Median EQ-5D-3L at 90 days	Secondary	0.46 (IQR 0.11-0.73)	0.78 (IQR 0.36-1.00)	Mean diff 0.24
Successful reperfusion (mTICI 2b/3)	Secondary	N/A	89/101 (88%)
Death within 90 days	Adverse	45/107 (42%)	34/110 (31%)	Adjusted risk ratio 0.75
sICH — SITS-MOST	Adverse	1/88 (1%)	6/102 (6%)	Risk ratio 5.18
sICH — ECASS II	Adverse	2/88 (2%)	9/102 (9%)	Risk ratio 3.88
Asymptomatic ICH	Adverse	3/88 (3%)	8/102 (8%)	Risk ratio 2.30
Procedural complications	Adverse	N/A	12/110 (11%)
Vessel dissection	Adverse	N/A	4 (4%)
Vessel perforation	Adverse	N/A	3 (3%)
Distal embolization	Adverse	N/A	5 (5%)
Pneumonia	Adverse	50 (47%)	51 (46%)
Malignant brain edema	Adverse	11 (10%)	14 (13%)
GI hemorrhage	Adverse	10 (9%)	15 (14%)
Acute renal insufficiency	Adverse	5 (5%)	3 (3%)
Cardiac ischemia	Adverse	4 (4%)	0
Acute heart failure	Adverse	22 (21%)	16 (15%)
Acute respiratory failure	Adverse	26 (24%)	21 (19%)

Subgroup Analysis

No significant interactions reported. Benefit of thrombectomy was consistent across subgroups: age ≤70 (adjusted rate ratio 1.70) vs >70 (3.04); male (1.61) vs female (2.95); NIHSS 6-20 (1.80) vs >20 (1.83); 6-12h (1.89) vs >12-24h (1.71); PC-ASPECTS ≥9 (1.42) vs <9 (2.17); proximal (1.96) vs middle (1.67) basilar occlusion. Trial not powered for subgroup analyses.

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 interim analysis of 212 patients (218 randomized of 318 planned) may overestimate treatment effect.
Original primary outcome (mRS 0-4) had CI crossing 1.0 (adjusted rate ratio 1.21, 0.95-1.54).
Rescue intracranial angioplasty/stenting was needed in 55%, reflecting predominantly atherosclerotic etiology that may differ from Western populations.

Funding

Chinese National Ministry of Science and Technology (Grant 2016YFC1301502). No industry involvement.

Based on: BAOCHE (The New England Journal of Medicine, 2022)