We aimed to perform a systematic review and meta-analysis of EC-IC bypass outcomes in patients with radiologically confirmed atherosclerotic occlusion or hemodynamic insufficiency from artery occlusion.

The extracranial-intracranial bypass is intended to prevent subsequent stroke and its associated events in atherosclerotic artery occlusion. However, its first large trial failed to show an advantage of the procedure compared to regular medical treatment. In the following years only some studies attempted to solve the matter. In addition, previous promising trials failed to reach a conclusion for various reasons, leaving the four-decade-long controversy unsolved. Considering the most recent data available, we sought to compare the intervention with non-surgical treatment in this population.

PubMed, EMBASE, and Cochrane databases were searched for randomized controlled trials (RCTs). A random effects model was used for the outcomes of interest. Heterogeneity was examined with the  I² statistics. R software was used for statistical analysis.

3 RCTs and 1,896 patients were included, of whom 921 (48,57%) were assigned to surgical intervention. The mean age ranged from 52 to 58 years. Mortality (2,41% vs. 2,79%; RR 0.90; 95% CI 0.51–1.60; p=0.721; I²=29%), disabling stroke (4,5% vs. 1,9%; OR 2.32; 95% CI 0.79–6.78; p=0.125; I²=0%), fatal stroke (1,6% vs. 0,7%; OR 1.65; 95% CI 0.12–22.44; p=0.706; I²=47%), mRS 0-1 (72% vs. 68%; OR 1.30; 95% CI 0.85–2.00; p=0.228; I²=0%), and mRS 0-2 (84% vs. 87%; OR 0.70; 0.41–1.22; p=0.208; I²=0%) did not reach a statistically significant difference between groups.

No statistical difference was observed for any of the 5 assessed outcomes due to limited available data. While trends suggest a slightly higher risk of disabling stroke post-surgery in individual studies, confidence intervals in the pooled analysis were wide. Heterogeneity among studies and limitations emphasize the need for larger RCTs to understand EC-IC bypass role in stroke-related outcomes prevention.