Background Accurate assessment of the prevalence of large vessel occlusion (LVO) in patients presenting with acute ischemic stroke (AIS) is critical for optimal resource allocation in neurovascular intervention.

Objective To perform a systematic review of the literature in order to identify the proportion of patients with AIS presenting with LVO on image analysis.

Methods A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in order to identify studies reporting LVO rates for patients presenting with AIS. Studies that included patients younger than 18 years, were non-clinical, or did not report LVO rates in the context of a consecutive AIS series were excluded. Characteristics regarding presentation, diagnosis, and LVO classification were recorded for each paper.

Results Sixteen studies, spanning a total of 11 763 patients assessed for stroke, were included in the qualitative synthesis. The majority (10/16) of articles reported LVO rates exceeding 30% in patients presenting with AIS. There was substantial variability in the LVO definitions used, with nine unique classification schemes among the 16 studies. The mean prevalence of LVO was 31.1% across all studies, and 29.3% when weighted by the number of patients included in each study.

Conclusions Despite the wide variability in LVO classification, the majority of studies in the last 10 years report a high prevalence of LVO in patients presenting with AIS. These rates of LVO may have implications for the volume of patients with AIS who may benefit from endovascular therapy.