Basilar artery occlusion (BAO) accounts for approximately 1% of all patients with stroke and leads to high mortality and disability rates [1]. Despite advances in the treatment of acute ischemic stroke, BAO remains associated with poor outcomes [2]. Recent studies have shown that combining endovascular treatment (EVT) with best medical management (BMM) improves outcomes in BAO compared with BMM alone [1,3,4]. However, large ischemic strokes are underrepresented in EVT trials, and randomized controlled trials comparing EVT with BMM alone in patients with BAO are lacking.

A prospective cohort study previously demonstrated that EVT was associated with better functional recovery at 90 days in patients with a posterior circulation Alberta Stroke Program Early CT Score (pc-ASPECTS) <6 [5,6]. However, long-term outcomes remain unclear. Therefore, this nationwide study aimed to assess 1-year outcomes of EVT in Chinese patients with BAO.

We conducted a retrospective analysis of the acute Posterior Circulation Ischemic Stroke Registry (PERSIST) study data [6-9].

Patients aged ≥18 years with BAO confirmed using computed tomography angiography, magnetic resonance angiography, or digital subtraction angiography, and with a pc-ASPECTS <6 were included.

The primary outcome was the modified Rankin Scale (mRS) score at 1 year. Secondary outcomes included mRS-based outcomes (favorable outcome [mRS 0-3] and functional independence [mRS 0-2]) and all-cause mortality at 1 year.

We used ordinal logistic regression to analyze the mRS shift and binary logistic regression for secondary outcomes, adjusting for confounding variables, including age, sex, National Institutes of Health Stroke Scale (NIHSS) score, pc-ASPECTS, estimated occlusion time, history of diabetes, hypertension, intravenous thrombolysis, stroke subtype, and location of occlusion. Propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) were used to balance treatment groups. All statistical analyses were performed using R version 4.1.3 (R Foundation for Statistical Computing, Vienna, Austria). Further details are provided in Supplementary Methods.

A total of 418 patients with 1-year follow-up data were included in this study. A flowchart is provided in Supplementary Figure 1. The baseline patient characteristics are provided in Supplementary Table 1. The adjusted common odds ratio (OR) for the primary outcome on the mRS with EVT compared to BMM was 1.61 (95% confidence interval [CI], 1.10-2.38). Patients undergoing EVT had a higher likelihood of functional independence (25.1% vs. 14.3%) and favorable outcome (35.5% vs. 21.8%), with an adjusted OR of 1.40 (95% CI, 1.06-1.86) and 1.48 (95% CI, 1.16-1.91), respectively (Table 1 and Figure 1). While mortality was lower in the EVT group (44.6% vs. 54.5%), this difference was not statistically significant (adjusted OR 0.70, 95% CI 0.46-1.08) (Table 1 and Supplementary Figure 2). The results of PSM and IPTW are provided in Table 1 and Supplementary Table 1 and are consistent with the main findings. Moreover, the findings revealed that EVT remained associated with a favorable outcome, regardless of whether the pc-ASPECTS was based on non-contrast computed tomography (NCCT) or magnetic resonance imaging (MRI) (Supplementary Tables 2 and 3). The treatment effect remained consistent in almost all pre-specified subgroups (Supplementary Figure 3).

The findings from this 1-year follow-up evaluation demonstrated that EVT in patients with acute BAO and large ischemic infarcts resulted in similar functional recovery to the originally reported results at 90 days. The percentage of patients in the EVT group who achieved a favorable outcome at 1 year (35.5%) was similar to that at 90 days (30.5%).

However, notable differences were observed between the two time points. First, during the extended follow-up period, the mortality rate in the EVT group was lower than that in the conventional treatment group at 1 year. However, after adjusting for confounding factors, the difference in all-cause mortality between the EVT and conventional treatment groups was not significant. Second, the percentage of patients with mRS scores of 0-2 and 0-3 at 1 year was higher than that at 90 days in both treatment groups. At 90 days, the proportions of functional independence and favorable outcomes were 22% and 30.5% in the EVT group, and 13.8% and 20% in the BMM group, respectively [6]. Moreover, the absolute difference in the percentage of patients with mRS scores of 0-2 and 0-3 at 1 year was greater than that observed between the two groups at 90 days.

Two recent randomized controlled trials conducted in China, the Endovascular Treatment for Acute Basilar Artery Occlusion (ATTENTION) and the Basilar Artery Occlusion Chinese Endovascular (BAOCHE) trials, demonstrated the efficacy of EVT in patients with BAO [3,4]. However, it is important to note that none of the trials included patients with pc-ASPECTS less than 6. A subgroup analysis of the EVT for Acute Basilar Artery Occlusion study (BASILAR) compared the efficacy and safety of EVT and BMM in patients with pc-ASPECTS <6 [10]. A total of 823 patients with BAO were included, and pc-ASPECTS was used to categorize them into three groups: pc-ASPECTS 8-10, 5-7, and 0-4. The results showed that EVT was beneficial for patients with pc-ASPECTS ≥5.

Moreover, a recent prospective study conducted in Korea that included patients with pc-ASPECTS <6 confirmed that EVT could benefit patients with acute BAO [5]. This study confirmed that EVT has better outcomes than BMM in patients with pc-ASPECTS <6, regardless of short-term or long-term prognosis. However, it should be noted that this benefit is more prominent in patients with pc-ASPECTS ≥4.

In conclusion, the benefit of EVT compared to BMM in patients with large ischemic stroke persisted at 1-year follow-up.