Increased risk for posterior circulation ischaemia in patients with vertebral artery hypoplasia: A systematic review and meta-analysis.

Abstract

Although several study protocols reported that vertebral artery hypoplasia can predispose to posterior circulation ischaemia, the role of vertebral artery hypoplasia in the risk of posterior circulation ischaemia still remains controversial. The aim of the present meta-analysis was to investigate the association of vertebral artery hypoplasia and posterior circulation ischaemia. We performed a systematic review and random effects meta-analysis of all eligible observational study protocols reporting prevalence rates of vertebral artery hypoplasia in patients with anterior circulation ischaemia and posterior circulation ischaemia. We identified eight study protocols including a total of 3875 acute ischemic stroke patients (mean age: 64.2 years, 61.3% males) and reporting a pooled prevalence of vertebral artery hypoplasia 18.6% (95%CI: 10.8-30.0%). In the overall analysis, a significantly higher probability of vertebral artery hypoplasia presence was found in posterior circulation ischaemia patients compared to patients with anterior circulation ischaemia (risk ratio = 2.12, 95%CI: 1.60-2.82, p < 0.001). In the subsequent sensitivity analysis, vertebral artery hypoplasia was again found to be significantly more prevalent in patients with posterior circulation ischaemia compared to anterior circulation ischaemia (risk ratio = 1.81, 95%CI: 1.58-2.06, p < 0.001), with no evidence of heterogeneity (I2 = 0%, p for Cochran Q = 0.55) between included studies. The present report is a meta-analysis of retrospective observational study protocols, with all the inherent limitations of included studies. The heterogeneity on the reported rates of vertebral artery hypoplasia could be attributed to differences in population age, sex, race, imaging protocols and vertebral artery hypoplasia definition between included studies. Our meta-analysis provides further evidence for a possible causal relationship between vertebral artery hypoplasia and cryptogenic posterior circulation ischaemia, an association which undoubtedly deserves further investigation in future prospective study protocols.