The prevalence and prognosis of asymptomatic intracranial atherosclerosis in a community-based population: Results based on high-resolution magnetic resonance imaging.

Background And Purpose: Intracranial atherosclerotic disease (ICAD) is a major cause of ischemic stroke in China, but the prevalence and prognosis of asymptomatic ICAD detected using high-resolution magnetic resonance imaging (HR-MRI) is largely unknown. The aim of this study was to investigate the prevalence and prognosis in order to guide neurologists in interpreting ICAD detected on HR-MRI.

Methods: We included stroke-free participants from a community-based prospective cohort (Shunyi study participants) who underwent HR-MRI between July 2014 and April 2016. The participants were divided into two groups: those with or without ICAD (ICAD and ICAD , respectively). ICAD included intracranial artery stenosis and non-stenotic plaque. The primary outcome was ischemic stroke. Cox proportional hazard models were used to evaluate the association between ICAD and event outcomes.

Results: A total of 1060 stroke-free participants evaluated by HR-MRI were included from the Shunyi study. The median age at HR-MRI was 56 years and 64.7% were female. The ICAD prevalence was 36.3% (n = 385). The ICAD group was older and had more cerebrovascular risk factors. The rates of ischemic stroke in the ICAD and ICAD groups were 1.3% (n = 9) and 5.2% (n = 20), respectively, with a median follow-up time of 54 months. ICAD was associated with an increased risk of ischemic stroke in the unadjusted and adjusted Cox models, with hazard ratios of 4.12 (95% confidence interval [CI] 1.87-9.05) and 2.50 (95% CI 1.05-5.94), respectively. The greatest risk of an event outcome was observed in participants with ≥70% stenosis or occlusion. The features of high-risk plaques were also identified.

Conclusions: We found that ICAD detected using HR-MRI increases the long-term risk of a first-ever ischemic stroke in a stroke-free population, suggesting that the current primary prevention protocol of stroke awaits further optimization.