Outcomes of Mechanical Thrombectomy in Acute Basilar Artery Occlusion with Mild to Moderate Symptoms.

Background and aims: The benefit of mechanical thrombectomy in patients with acute basilar artery occlusion (BAO) and NIHSS<10 is unclear, since this sub-population was mainly excluded from large trials. We aimed to compare the outcomes of patients treated with mechanical thrombectomy (MT) vs intravenous thrombolysis (IVT) in this population. Methods: We emulated a hypothetical trial including patients with BAO and NIHSS<10, treated with MT (±IVT) from the Italian Registry of Endovascular Stroke Treatments, and with IVT only from the SITS Registry. The primary outcome was a score 0-2 at the 90-day modified Rankin Scale (mRS). We used inverse probability weighting (IPW) adjusted for prespecified covariates to weight each individual’s contribution to the outcome. We used a robust variance estimator to account for potential replications of patients. Results: After applying IPW, n=710 with MT and n=707 with IVT patients were included. MT was associated with higher odds of 90-day mRS 0-2 (aOR 1.56 [95%CI 1.04-2.03]). MT was also associated with excellent outcome (mRS 0-1) (aOR 2.01 [95%CI 1.37–2.95]), and reduced in-hospital death (aOR 0.448 [95%CI 0.25-0.78]). Among the tested subgroups, MT had a larger effect on independence in patients with NIHSS 6-9 compared to those with NIHSS<6 (p for interaction 0.02). Conclusions: In a large scale targeted trial emulation, in patients with Stroke from BAO and NIHSS<10 MT was associated with better functional outcomes and lower rates of in-hospital mortality compared to patient treated with IVT alone. Further research is needed for patients with NIHSS<6.