Outcomes predictors in patients with basilar artery occlusion and mild deficits, treated with mechanical thrombectomy: A multicenter retrospective observational study

Abstract

Background: Basilar artery occlusion (BAO) patients presenting with NIHSS<10 were an underrepresented population in recent clinical trials assessing the benefit of mechanical thrombectomy (MT) over best medical management (BMM). Despite European guidelines suggesting BMM as first treatment approach in such patients, current evidence is conflicting and MT could still be beneficial in carefully selected patients. In this study we aimed to investigate pre-procedural and procedural variables influencing the neurological outcome in MT-treated patients presenting with BAO and mild symptoms.

Methods: We conducted a retrospective observational study collecting data from ten large European stroke centers gathering consecutive patients presenting with BAO and NIHSS<10, between January 2017 and December 2024. We performed an outcome analysis in MT-treated patients with a pre-event mRS < 3, assessing the achievement of a 3-month modified Rankin Scale (mRS) score of 0-2 (vs 3-6) and 0-3 (vs 4-6). A sensitivity analysis restricted to patients with admission NIHSS<6 was conducted for the mRS 0-2 outcome.

Results: Among 148 BAO patients with onset NIHSS<10, 128 (86.5%) were treated with immediate MT plus BMM, while 20 (13.5%) with BMM alone of which 8/11 (72.7%) were switched to a rescue MT after neurological deterioration. Among 133 MT-treated patients, 93/133 (69.9%) reached mRS 0-2 and 101/133 (75.9%) mRS 0-3. Overall, in MT-treated patients, involving both immediate MT and rescue MT, an occlusion localized beyond the superior cerebellar artery was an independent predictor of mRS 0-2 [O.R. 7.11; 95% C.I. 2.50-20.24; p < 0.001] and mRS 0-3 [O.R.12.07; 95% C.I. 3.27-44.55; p < 0.001] at three months. Distal occlusion acted as an independent predictor of mRS 0-2 also in the subgroup with admission NIHSS<6 [O.R. 5.13; 95% C.I. 1.19-22.11; p = 0.028].

Conclusion: In BAO patients with mild symptoms undergoing MT, a distal occlusion located beyond the superior cerebellar artery is a strong independent predictor of favorable functional outcome at three months. These findings highlight the importance of considering occlusion site when selecting BAO patients with mild symptoms for MT.

Keywords: Basilar artery; Mechanical thrombectomy; Medical therapy; NIHSS; Outcome.