Extracranial–intracranial bypass for symptomatic intracranial arterial occlusion: a meta-analysis of individual patient data

Patients with symptomatic atherosclerotic internal carotid artery (ICA) or middle cerebral artery (MCA) occlusions face a high risk of recurrent ischaemic stroke despite best medical therapy. Previous trials of extracranial-intracranial (EC-IC) bypass surgery showed no benefit for stroke prevention in this population, but they may have been underpowered. This study evaluates the efficacy of EC-IC bypass surgery in reducing the risk of the composite outcome of stroke or death within 30 days or ipsilateral ischaemic stroke beyond 30 days through 2 years. Following a PROSPERO-registered protocol (CRD42023457824), we conducted a systematic review of PubMed, Embase and Cochrane Library for randomised trials, comparing the use of EC-IC bypass surgery plus medical therapy versus medical therapy alone. The primary outcome was a composite of stroke or death within 30 days or ipsilateral ischaemic stroke beyond 30 days through 2 years after randomisation. One-stage and two-stage meta-analyses using reconstructed individual patient data in hazard ratios (HRs) were performed. Four trials (2102 participants) were included. No statistically significant differences were observed between the two groups in the one-stage (HR 1.019, 95% confidence interval CI 0.860-1.209, P = 0.06) and two-stage (HR 0.954, 95% CI 0.841-1.241, P = 0.21) meta-analyses. Rates of ipsilateral ischaemic stroke, any stroke or death, and any stroke were also similar between groups at 2 years. In symptomatic ICA or MCA occlusion, adding bypass surgery to medical therapy does not significantly lower the risk of the composite outcome of stroke or death compared to medical therapy alone.