<b><i>Background:</i></b> The coincidence of coronary artery disease (CAD) and carotid artery stenosis (CAS) was observed. However, the association between pre-existing CAD and ischemic stroke (IS) outcome in patients with high-grade CAS remains unclear. We aimed to investigate the association between pre-existing CAD and outcomes of acute IS patients with high-grade CAS. <b><i>Methods:</i></b> From January 1, 2007, to April 30, 2012, we enrolled 372 acute IS patients with high-grade CAS and prospectively observed them for 5 years. Demographic features, vascular risk factors, comorbidities, and outcomes were compared between patients with and without pre-existing CAD. <b><i>Results:</i></b> Among 372 individuals, 75 (20.2%) patients had pre-existing CAD and 297 (79.8%) patients did not have pre-existing CAD. The prevalence rates of hypertension, congestive heart failure, chronic kidney disease, and gout in patients with pre-existing CAD were significantly higher than in those without pre-existing CAD (<i>p</i> = 0.017, <i>p</i> < 0.001, <i>p</i> = 0.002, and <i>p</i> < 0.001, respectively). The multivariate Cox proportional hazards model revealed that pre-existing CAD was a significant risk factor for a 5-year all-cause mortality in acute IS patients with high-grade CAS (hazard ratio = 2.26; 95% confidence interval = 1.35–3.79; <i>p</i> = 0.002). <b><i>Conclusion:</i></b> Pre-existing CAD was associated with an increased risk of 5-year mortality in acute IS patients with high-grade CAS. Intensive treatment for the pre-existing CAD may reduce long-term mortality in acute IS patients with high-grade CAS.
External carotid artery plaques are associated with intracranial stenosis in patients with advanced coronary artery disease
