Endovascular Therapy in Patients With Sudden Versus Nonsudden Onset of Basilar Artery Occlusion Symptoms

Posterior circulation stroke resulting from basilar artery occlusion (BAO) can carry substantial morbidity and death risk without reperfusion treatment. ¹ While the efficacy of endovascular treatment (EVT) in anterior circulation stroke has been well established, its effectiveness in BAO has been a subject of debate until recently. ² , ³ , ⁴ , ⁵ , ⁶ , ⁷ , ⁸ , ⁹ In October 2022, 2 pivotal randomized clinical trials, ATTENTION (Endovascular Treatment for Acute Basilar Artery Occlusion—A Multicenter Randomized Clinical Trial) and BAOCHE (Basilar Artery Occlusion Chinese Endovascular), were published, conclusively demonstrating the superiority of EVT over medical management for acute BAO within 24 hours of stroke onset. ¹⁰ , ¹¹ , ¹² A subsequent meta‐analysis of BAO randomized trials further confirmed the benefit of EVT, with a 2‐fold increase in the odds of a favorable outcome (modified Rankin Scale score, 0–3) and reduced death at 3 months compared with medical management. ¹³ Additionally, 2 large prospective trials demonstrated the positive impact of EVT in patients with acute BAO. ¹⁴ , ¹⁵ The BASILAR (Assessment of Endovascular Treatment for Acute Basilar Artery Occlusion via a Nationwide Prospective Registry) study, a large prospective registry of 829 patients with acute BAO, compared EVT with medical management across 47 stroke centers in 15 provinces in China. ¹⁴

Patients with BAO can have varying types of clinical presentation, from a stuttering course with later deterioration associated with an occlusion to a maximal and sudden deficit at onset. ¹⁶ It is not known whether there is a difference in patient outcomes according to the tempo of these presentations. Using data from the prospective BASILAR study, Zhu et al ¹⁷ in this issue of Journal of the American Heart Association (JAHA) assessed the potential impact of the different clinical presentation patterns on outcomes in patients undergoing EVT with BAO. The distinctive anatomy, underlying stroke pathogenesis, collateral circulation, and blood flow patterns of the posterior circulation can result in varied symptoms with BAO onset. Sudden onset to maximal deficit (SOTMD) was defined in their study as acute neurological deficit that peaked immediately or within 5 minutes of onset without progressive exacerbation or symptom fluctuation.

Among the 647 patients with acute BAO undergoing EVT in the BASILAR study, 270 had SOTMD, and 377 had nonsudden onset to maximal deficit (NSOTMD). After 1:1 propensity score matching between the SOTMD and NSOTMD groups, the study found no difference in favorable outcomes at 90 days after EVT (33.3% versus 31.0%, respectively; odds ratio, 0.88 [95% CI, 0.58–1.34]) between the 2 groups. However, patients with SOTMD exhibited higher mortality rates after EVT than those with NSOTMD (50.0% versus 43.5%, respectively; P=0.008), with an adjusted odds ratio of 1.67 (95% CI, 1.14–2.44). The higher mortality rate in the SOTMD was linked to the higher National Institutes of Health Stroke Scale scores at presentation, older age, and higher proportion of coronary artery disease in the SOTMD group. In addition, baseline National Institutes of Health Stroke Scale score, baseline posterior circulation Acute Stroke Prognosis Early Computed Tomography Score, diabetes, recanalization, and collateral score were identified as independent predictors of favorable outcomes and death in the patient cohort with SOTMD.

The pattern of stroke onset has often been thought to be related to the pathogenesis of stroke, with sudden maximal onset related to cardioembolic pathogenesis and a stuttering course of symptoms in the same territory related to local atherosclerotic disease. Before propensity score matching, differences in stroke pathogenesis between the 2 groups suggest this correlation, with atherosclerotic disease noted in 71.9% in the NSOTMD group versus 54.4% of SOTMD, and cardioembolism in 36.3% of the SOTMD group versus 19.9% in the NSOTMD group. Interestingly, collateral status in the 2 groups was similar. After 1:1 propensity score matching, there was no difference in the pathogenesis of ischemic stroke or favorable outcome (modified Rankin Scale score, 0–3). These findings align with a prior study, indicating no distinction in the 90‐day or long‐term functional outcomes (modified Rankin Scale score, 0–2) for patients undergoing EVT with BAO associated with intracranial artery atherosclerosis or embolism. ¹⁸

Similar to the anterior circulation, there was a significant time dependence for EVT regarding the 90‐day clinical outcomes of patients with acute BAO in both SOTMD and NSOTMD groups, suggesting that the earlier the treatment, the better the outcomes. However, the impact of onset to puncture time on clinical outcomes and death differed between the SOTMD and NSOTMD groups after EVT. For patients with SOTMD, the time‐benefit curve suggested that earlier treatment correlated with better outcomes, with a suggested optimal treatment time window of 6 hours from onset to puncture. Conversely, patients with NSOTMD demonstrated a decline in the probability of a favorable outcome from 38.0% at 1 hour to 18.0% at 8 hours, with EVT within 8 hours significantly correlated with a good prognosis. While both groups showed significant time dependence, patients with SOTMD showed a stronger time dependence for EVT in terms of death, and the NSOTMD group showed stronger time dependence regarding favorable clinical outcomes.

While time is an important factor to consider in the treatment of patients with BAO, as shown in this study, it may also be important to consider other factors including the extent of baseline ischemia when making treatment decisions. Most patients in this cohort were treated in an early time window (overall, within a median of 6 hours from onset to puncture) and were without extensive baseline ischemia (posterior circulation Acute Stroke Prognosis Early Computed Tomography Score median, 8). Patients presenting in a later time window were not as well represented. It is also not known whether these patients had witnessed or unwitnessed presentations; in unwitnessed patients, one may not be able to define the semiology of onset. As the ATTENTION and BAOCHE trials with patients presenting up to 12 and 24 hours of estimated time of onset also derived benefit from EVT on the basis of a good posterior circulation Acute Stroke Prognosis Early Computed Tomography Score, ¹⁰ , ¹¹ , ¹⁹ the results of this BASILAR analysis should not dismiss patients from being considered for EVT if patients are presenting in a later time window and do not have extensive baseline ischemia. ²⁰

While the study has its limitations, including the inherent challenges of a nonrandomized study and lack of differentiation as to whether symptoms were witnessed or unwitnessed, it provides valuable insight into the realm of BAO treatment and highlights the significance of EVT in patients with BAO, for both patients with SOTMD and patients with NSOTMD. While BAO trial data have shown the benefit of EVT extended to the 24‐hour window, one cannot be complacent in the treatment of patients presenting in the early window. This analysis underscores the critical role of timing in treatment of patients with BAO, emphasizing the need for swift intervention for patients with both SOTMD and NSOTMD.

Disclosures

Dr Nguyen is on the advisory board for Idorsia, Brainomix. Dr Abdalkader has no disclosures to report.