Acute basilar artery occlusion, should I choose endovascular therapy or drug therapy alone?

*Only for medical professionals' reference to read the latest research to tell you! Acute basilar artery occlusion (BAO) is a potentially catastrophic disease, accounting for 1% of all ischemic strokes and 5% of large vessel occlusive (LVO) strokes.

Although several large randomized controlled trials (RCTs) have confirmed the safety and effectiveness of thrombectomy in anterior circulation large vessel occlusive acute ischemic stroke since 2015.

However, high-level evidence of thrombectomy in posterior circulation is still relatively lacking.

Regarding the best treatment for BAO, whether endovascular therapy (EVT) should be implemented or just drug therapy, there are some controversies among various studies.

Next, introduce the recently published and well-known two major studies of BASILAR and BASICS.

1.
BASILAR[1] comes from Professor Yang Qingwu, Director of Neurology Department of the Second Affiliated Hospital of the Army Military Medical University (Xinqiao Hospital, Chongqing City).
The research team and 47 hospitals across the country jointly carried out a multi-center clinical registration study of acute BAO using EVT ( The EVT for Acute Basilar Artery Occlusion Study, BASILAR), announced its research results at the 2020 International Stroke Conference, and published it online on February 20, 2020 in JAMA Neurology.

This study aims to evaluate the safety and effectiveness of EVT in patients with acute BAO.

Figure 1: Screenshot of the title of the paper.
This study is a registration study, and the inclusion criteria are as follows: 1.
Patient age ≥18 years; 2.
Onset time <24h; 3.
BAO diagnosed by CTA/MRA/DSA; 4.
Onset 4.
5h/ Receive intravenous rt-PA/urokinase thrombolysis within 6 hours; 5.
Sign informed consent. Patients were divided into standard drug treatment group (control group) and standard drug therapy combined with thrombus removal treatment group (thrombus removal group) based on actual treatment.

The results showed that the median mRS scores of the thrombus removal group and the control group were 5 (IQR, 2-6) and 6 (IQR, 5-6) at 90 days postoperatively.

Patients in the thrombus removal group tend to have a better prognosis (aOR, 3.
08; 95% CI, 2.
09-4.
55; P<0.
001).

The propensity score matching analysis also verified the results of the complete cohort.

*IQR is the median and aOR is the odds ratio.
Figure 2: Distribution of mRs scores at 90 days.
The thrombectomy group had a higher prognosis (mRS 0-3) at 90 days after surgery than the control group (32% vs 9.
3%; P <0.
001; aOR, 4.
70; 95% CI, 2.
53-8.
75; P <0.
001), the mortality rate is lower than the control group (46.
2% vs 71.
4%; P <0.
001; aOR, 2.
93; 95% CI, 1.
95 to 4.
40 ; P＜0.
001).

The blood vessel recanalization rate in the thrombus removal group was 80.
7%.

Figure 3: Primary and secondary outcomes and safety outcomes 2.
BASICS [2] On May 20, 2021, NEJM published an international, multi-center, randomized controlled BASICS study conducted by 23 centers in 7 countries online As a result, whether EVT treatment or drug treatment for BAO stroke adds to the evidence.

Figure 4: Literature information N Engl J Med 2021; 384:1910-1920 patients were enrolled at 1:1, all within 6 hours of the onset of stroke caused by BAO.

Patients were randomly assigned to enter the EVT group or the drug treatment group.

The primary outcome is a good functional outcome, defined as an mRS score of 0-3 points after 90 days.

The primary safety outcome was symptomatic intracranial hemorrhage within 3 days of treatment and death within 90 days.

Results A total of 300 patients (154 in the EVT group and 146 in the drug treatment group) were included.

78.
6% of patients in the EVT group used intravenous thrombolysis, while 79.
5% of the patients in the drug treatment group used intravenous thrombolysis.

The median time to start endovascular treatment after the onset of stroke was 4.
4 hours.

Of the 154 patients in the EVT group, 68 (44.
2%) achieved good functional outcomes, while 55 of the 146 patients in the drug treatment group (37.
7%) achieved good functional outcomes (RR, 1.
18; 95% CI, 0.
92- 1.
50).

Figure 5: The distribution of mRS scores in the two groups was 4.
5% of patients with symptomatic intracranial hemorrhage after EVT treatment, and 0.
7% in the drug group (RR, 6.
9; 95% CI, 0.
9-53.
0).

The 90-day mortality rate was 38.
3% and 43.
2% (RR 0.
87; 95% CI, 0.
68-1.
12).

*RR is the relative risk.
Figure 6: Comparison of outcomes between the two groups.
Among BAO stroke patients, EVT therapy and drug therapy have no significant difference in good functional outcomes.
However, the wide confidence interval of the primary outcome suggests that the results of this trial cannot be completely ruled out Benefits of EVT treatment.

Therefore, larger trials are needed to determine the effectiveness and safety of EVT therapy for BAO.

3.
Enlightenment 1.
Compared with the anterior circulation, EVT therapy still has a big gap in the application of BAO; many previous studies of EVT therapy have not shown obvious advantages.

The BASICS study is an international, multi-center, randomized controlled clinical study jointly conducted by 23 centers in 7 countries.

Although the final results of the study did not show the obvious advantages of EVT treatment, there are still some problems worth pondering.

1) The BASICS study took 8 years (2011-2019), reflecting the actual problem of the slow enrollment of post-circulation studies, and it is urgent for more countries and more clinical centers to strengthen cooperation; 2) The enrollment span of the study is too long.
Even in the same group, there are some differences in treatment methods, and the treatment devices in the EVT group may also be different. 3) BASICS relaxed the entry criteria in the later period, for example, the elderly and patients with low scores on the National Institutes of Health Stroke Scale (NHISS) were also included.

In the subgroup analysis, different NHISSS scores also reflect the difference in the effect of EVT treatment.

4) Insufficient image evaluation in the study, mainly based on NCCT, CTA and MRA, lack of more advanced imaging technology, so the conclusions drawn may be biased.

2.
We all know that before 2015, the great vessel occlusion of the anterior circulation of EVT did not achieve very satisfactory results.
Since 2015, several large RCT trials have passed the screening of images and confirmed the acute ischemic stroke of the anterior circulation of EVT.
The safety and effectiveness of the system.

Similarly, whether EVT can show advantages in the treatment of BAO stroke may depend more on the patient's choice, which depends on the application of more advanced imaging techniques.

At present, CTP or NMR sequence has not been applied to the post-cycle RCT research including this research.

Some high-quality journals published this year, whether it is CTP or NMR DWI sequence, also reflect the obvious correlation to the prognosis of patients.

A subgroup analysis of the BASICS study found that patients with severe stroke (NIHSS score ≥10) often have a slightly better prognosis with EVT.

For patients with mild injury or NIHSS score <10, drug therapy may be the best treatment option.

Therefore, EVT and drugs are viable options for BAO patients, and clinicians should provide patients with personalized treatment according to the specific conditions of each case.

In addition, the selection of accurate BAO patients (selected by imaging) is particularly important, and may be a key issue that needs to be urgently resolved in the future for BAO thrombus removal.

Reference materials: [1]Writing Group for the BASILAR Group,Zi W,Qiu Z,Wu D,Li F,Liu H,Liu W,Huang W,Shi Z,Bai Y,Liu Z,Wang L,Yang S,Pu J, Wen C, Wang S, Zhu Q, Chen W, Yin C, Lin M, Qi L, Zhong Y, Wang Z, Wu W, Chen H, Yao X, Xiong F, Zeng G, Zhou Z, Wu Z, Wan Y, Peng H, Li B, Hu X, Wen H, Zhong W, Wang L, Jin P, Guo F, Han J, Fu X, Ai Z, Tian X, Feng X, Sun B, Huang Z, Li W , Zhou P, Tu M, Sun X, Li H, He W, Qiu T, Yuan Z, Yue C, Yang J, Luo W, Gong Z, Shuai J, Nogueira RG, Yang Q.
Assessment of Endovascular Treatment for Acute Basilar Artery Occlusion via a Nationwide Prospective Registry.
JAMA Neurol.
2020.
[2]2.
LCMLangezaal,EJRJvan der Hoeven,FJAMont'Alverne,et al.
Endovascular Therapy for Stroke Due to Basilar-Artery Occlusion.
N Engl J Med 2021,384: 1910-1920.
Text first published: Medical Neurology Channel Article Author: Li Tuming, Deputy Chief Physician Responsible Editor: Mr.
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