Outcomes of Mechanical Thrombectomy in Patients With Acute Basilar Artery Occlusion With Mild to Moderate Symptoms

Background and Objectives The benefit of mechanical thrombectomy (MT) in patients with acute ischemic stroke (AIS) with basilar artery occlusion (BAO) and a baseline National Institute of Health Stroke Scale (NIHSS) score <10 is unclear because this subpopulation has been substantially excluded from large clinical trials. The aim of our study was to determine whether MT ± IV thrombolysis (IVT) improves functional outcomes compared with IVT alone in patients with BAO and a NIHSS score <10. Methods We emulated a hypothetical trial including adult patients with BAO, a baseline NIHSS score <10, and prestroke modified Rankin scale (mRS) scores 0–2, comparing MT (±IVT) with IVT alone. We acquired data from patients receiving MT (±IVT) within 24 hours of onset from the Italian Registry of Endovascular Treatment in Acute Stroke and data from patients treated only with IVT within 9 hours of symptom onset from the SITS International Stroke Thrombolysis Register, from 2011 until 2021. We used inverse probability weighting (IPW) adjusted for prespecified covariates to weight each individual’s contribution to the outcome. The primary outcome was 90-day mRS scores 0–2. Secondary outcomes included 90-day mRS scores 0–1, 90-day mRS scores 4–5, mortality at 90 days, in-hospital death, and symptomatic intracerebral hemorrhage. Results Among the 764 patients recruited from the 2 databases (477 men [62.4%]; mean age [±SD] 67.88 [±13.9] years), 410 (53.7%) received MT±IVT and 354 (46.3%) only IVT. After applying IPW, our population was composed of 710 MT and 707 IVT patients. Of these, 454 MT-treated (63.9%) and 383 IVT-treated (54.2%) patients had a 90-day mRS score of 0–2 (adjusted odds ratio (aOR) 1.56 [95% CI 1.04–2.03]). MT was also associated with a higher rate of mRS scores 0–1 (aOR 2.01 [95% CI 1.37–2.95]) and a lower rate of in-hospital death (aOR 0.45 [95% CI 0.25–0.78]). Among the subgroups tested, MT had a larger effect on 90-day mRS scores 0–2 for patients with NIHSS scores 6–9 than for patients with a NIHSS score <6 (p for interaction 0.02). Discussion In a large-scale target trial emulation on patients with stroke from BAO and a NIHSS score <10, MT was associated with better functional outcomes compared with IVT alone. Further research is needed to confirm the benefit of MT in patients with a NIHSS score <6. Classification of Evidence This study provides Class III evidence that MT ± intravenous thrombolysis is associated with better 90-day functional outcomes in patients with BAO and a NIHSS score < 10 compared with intravenous thrombolysis alone.