Factors influencing functional recovery in posterior circulation stroke following mechanical thrombectomy: a systematic review and meta-analysis

Introduction Posterior circulation stroke (PCS) in the vertebrobasilar system carries high morbidity and mortality. While mechanical thrombectomy (MT) is effective in selected patients, functional recovery after MT for PCS remains variable and may be influenced by clinical, imaging and procedural factors. Objectives To summarise clinical, imaging and procedural factors associated with functional recovery, defined as modified Rankin Scale 0–2 at 90 days, after MT in PCS. Methods This systematic review and meta-analysis searched EMBASE, MEDLINE, PubMed, EBSCO, Scopus, CNKI, SSRN, bioRxiv and medRxiv from inception until 31 December 2025. Inclusion criteria were adult patients with PCS who underwent MT in clinical trials or observational studies. Risk Of Bias In Non-randomised Studies-of-Exposure was assessed. Meta-analysis used a random-effects model to pool ORs with 95% CIs, assessing heterogeneity via I 2 and Cochran’s Q test (PROSPERO: CRD42024626263). Results We analysed 12 094 patients from 75 studies. Predictors of favourable outcomes included higher posterior circulation-Alberta Stroke Programme Early CT Score (OR=1.80, 95% CI 1.59 to 2.03, p<0.001, I 2 =0.0%), intravenous thrombolysis (OR=1.66, 95% CI 1.31 to 2.1, p<0.001, I 2 =21.7%), first-pass effect (OR=2.36, 95% CI 1.84 to 3.03, p<0.001, I 2 =9.28%) and modified thrombolysis in cerebral infarction 2b/3 (OR=3.58, 95% CI 2.31 to 5.55, p<0.001, I 2 =58.43%). Poor outcomes were associated with higher baseline National Institutes of Health Stroke Scale (OR=0.92, 95% CI 0.89 to 0.95, p<0.001, I 2 =85.09%), diabetes mellitus (OR=0.56, 95% CI 0.43 to 0.72, p<0.001, I 2 =24.63%), hypertension (OR=0.73, 95% CI 0.59 to 0.91, p=0.010, I 2 =0.0%) and general anaesthesia use (OR=0.56, 95% CI 0.36 to 0.89, p=0.010, I 2 =64.53%). Conclusions Stroke severity, imaging scores and procedural success are factors consistently reported to be associated with functional outcomes in PCS after MT. Although the independence of these factors cannot be determined from this analysis, these findings may help summarise current evidence on reported prognostic factors and support future prospective validation using standardised protocols.