Abstract WP074: Impaired Cerebrovascular Reactivity Predicts Stroke Risk in Asymptomatic High-Grade Carotid Stenosis or Occlusion: A Systematic Review and Meta-Analysis

Background: The management of asymptomatic high-grade carotid stenosis remains challenging, particularly in identifying individuals at highest risk for hypoperfusion-related stroke. Impaired cerebrovascular reactivity (CVR) has emerged as a potential predictor of future cerebrovascular events. Objective: To perform a systematic review and meta-analysis to quantify the association between impaired CVR and the risk of ipsilateral ischemic stroke or TIA in patients with asymptomatic high-grade carotid stenosis/occlusion. Methods: A systematic literature search of PubMed, Embase and Scopus was conducted from inception till July 2025. Eligible studies included asymptomatic patients with ≥70% carotid stenosis or occlusion who underwent CVR assessment and reported ipsilateral ischemic stroke or TIA outcomes. Pooled relative risks (RR) with 95% confidence intervals (CIs) were calculated using a random-effects model. Forest plots were generated, and heterogeneity was assessed using the chi-square test and the I 2 statistic. Results: Six prospective observational studies including a total of 361 patients with asymptomatic high-grade carotid stenosis/occlusion (mean age 70.4 years; 73.6% male; 71.2% with hypertension; 28.6% with diabetes; 29.6% current or former smokers) were included in the analysis. Of these, 120 patients had impaired CVR and 241 had preserved CVR. Transcranial Doppler (TCD) was the most frequently used modality to assess CVR, with acetazolamide or CO 2 as the vasodilatory stimulus. Following CVR assessment, patients were monitored for a weighted mean follow-up of 26.2 months (range: 21.5 to 42.5 months). The incidence of ipsilateral ischemic stroke or TIA was 14.2% in patients with impaired CVR versus 2.1% in those with preserved CVR (RR 3.98; 95% CI 1.62–9.76; P = 0.003; Figure 1). When limited to ipsilateral ischemic stroke alone, the incidence was 21.4% in the impaired CVR group compared to 4.3% in the preserved CVR group (RR 3.35; 95% CI 1.54–7.25; P = 0.002; Figure 2). Conclusions: Impaired CVR is associated with a 3- to 4-fold increased risk of ipsilateral ischemic stroke or TIA in patients with high-grade carotid stenosis/occlusion. CVR assessment may help stratify risk and guide individualized management in this population.