NEJM: Acute basilar artery occlusion thrombectomy test - BAOCHE

Randomized trials of anterior circulation aortic occlusion leading to acute stroke have shown some benefit
from endovascular thrombectomy.
Acute basilar artery occlusion is a poorly prognostic type of stroke, but these trials exclude these patients
.

The BEST trial and the BASICS trial did not find thrombectomy with basilar artery occlusion superior to medical treatment, but both trials had methodological limitations
.
Anatomical and pathophysiologic features, the brainstem and cerebellum supplied by the basilar artery branches are more resistant to ischemia than structures supplied by the anterior cerebral circulation, so the time window for reperfusion therapy may be longer
than the latter.

In October 2022, Professor Ji Xunming et al.
from Xuanwu Hospital announced the results of the BAOCHE test in NEJM to evaluate the efficacy and risk
of endovascular thrombectomy within 6-24 hours of stroke due to basilar artery occlusion.

BAOCHE is a controlled trial of investigator-initiated, multicenter, open-label, blinded assessment of outcomes
.
Key inclusion criteria included age 18 to 80 years, basilar artery occlusion or bilateral vertebral artery intracranial segment occlusion, ability to receive treatment within 6 to 24 hours of onset (calculated from the last appearance of no acute stroke symptoms [excluding isolated vertigo]), mRS 0-1 before stroke, NIHSS>=10 points at onset (due to inclusion difficulties, it was changed to NIHSS>=6 points after 61 patients were included).

Key exclusion criteria included recent intracranial hemorrhage, posterior circulation extensive infarction (defined as CT, CTA raw image, or PC-ASPECTS score on DWI< = 6 [posterior circulation ASPECTS score] (1 point each for early ischemic changes or low density in the left and right thalamic, cerebellum, or posterior cerebral artery regions, PC-ASPECTS score = 10- or sum of scores), or large brainstem infarction on CT, CTA raw images, or MRI, defined as pontine-midbrain index >2 points [range 0-8 points, the larger the value, the heavier the infarct load; Infarction range<50% hemipontine or midbrain score 1 point, >50% score 2 points]).

Included patients were randomized in a 1:1 ratio to receive thrombectomy plus standard medical treatment (thrombectomy group) or standard medical treatment alone (control group).

Patients within 4.
5 hours of onset can receive intravenous thrombolytic therapy
.
Solitaire stent and separable self-expanding stent are used to remove thrombus and restore blood flow
.
Salvage reperfusion therapy of basilar or vertebral arteries is not permitted with equipment or drugs other than balloon angioplasty or stent salvage reperfusion therapy
.

The primary outcome was initially set as 90-day mRS 0 to 4, which was later changed to good functional status (mRS 0-3), and the primary safety outcomes were symptomatic intracranial haemorrhage at 24 hours and 90-day mortality
.

A total of 217 patients (110 in the thrombectomy group and 107 in the control group) were included in the analysis; The median time for randomization was 663 minutes
after onset.
Due to the efficacy of thrombectomy, the inclusion of patients
was discontinued at the time of pre-specified interim analysis.
Thrombolysis was performed in 14% of patients in the thrombectomy group and 21% of patients in the control group
.
The mRS scores ranged from 0 to 3 (primary outcome) for 51 patients (46%) in the thrombectomy group and 26 patients (24%) in the control group (adjusted RR 1.
81; 95% CI 1.
26 to 2.
60; P < 0.
001
).
The revised Rankin scale scored from 0 to 4, with initially set primary outcomes of 55% and 43% (adjusted RR 1.
21; 95% CI 0.
95 to 1.
54).

Symptomatic intracranial hemorrhage occurred in 6 of 102 patients (6%) in the thrombectomy group and 1 in 88 (1%) in the control group (RR 5.
18; 95% CI 0.
64 to 42.
18).

Mortality at 90 days was 31% in the thrombectomy group and 42% in the control group (adjusted RR 0.
75; 95% CI 0.
54 to 1.
04).

11% of patients who underwent thrombectomy experienced surgical complications
.

The authors concluded that for stroke patients with basilar artery occlusion between 6 and 24 hours of onset, the proportion of patients with good functional status at 90 days of thrombectomy was higher than with medical therapy, but was associated with
surgical complications and more intracerebral haemorrhage.

Important data: Thrombectomy versus control, atrial fibrillation 13% versus 12%, baseline NIHSS score (IQR) 20 vs 19, intravenous thrombolysis (%) 15 vs 23, PC-ASPECTS score 8 vs 8, pontine-midbrain index (IQR) 1 vs 1, proximal basilar artery occlusion site 50% vs 43%, midsection 37% vs 35%, distal 12% vs 22%, onset to random time (IQR) 664 vs 662 minutes, Onset to revascularization 790 min vs NA, hospital to femoral artery puncture 153 min vs NA, femoral artery puncture to revascularization 85 min vs NA.

Outcomes: dramatic improvement in neurological function 25% versus 10% at 24 hours, basilar artery patency 92% versus 19% at 24 hours, and DSA reperfusion 88% versus NA
.