Prognosis of Incidentally Detected Asymptomatic Intracranial Atherosclerotic Stenosis: A Prospective Hospital-Based Cohort Study.

Asymptomatic intracranial atherosclerotic stenosis (ICAS) is frequently identified in stroke screening programs, particularly in Asian populations. However, the prognosis and management strategies for incidentally detected asymptomatic ICAS in hospital-based, stroke-free populations remain unclear. This study aimed to investigate the incidence of symptomatic transition and associated long-term prognostic evolution in this population, providing evidence to inform primary stroke prevention. We conducted a prospective cohort study that included 1004 patients with asymptomatic ICAS (≥ 50%) screened by transcranial Doppler ultrasound (TCD) between January 2016 and May 2022, with follow-up through August 2023. Using the Fine and Gray competing risk model, we analyzed the incidence of symptomatic transition, defined as a first-ever ischemic stroke or transient ischemic attack occurring within the ICAS territory. Post-transition outcomes, including recurrent stroke, major adverse cardiovascular events (MACE), disability (modified Rankin Scale score > 2), and patient-reported cognitive decline (Everyday Cognition-12 score ≥ 2), were evaluated by comparative analysis. Over a median follow-up of 3.7 years (IQR 2.4-5.2), 43 (4.3%) patients with asymptomatic ICAS experienced a symptomatic transition under routine clinical surveillance, yielding a 5-year cumulative transition rate of 5.6%. After adjusting for potential confounders, hypertension (HR 3.33, 95% CI 1.25-8.87) and hyperlipidemia (HR 2.71, 95% CI 1.28-5.74) were independent predictors of the transition. Through extended follow-up, post-transition risks significantly increased for ischemic stroke (hazard ratio HR 3.37, 95% CI 1.17-9.68), MACE (HR 4.48, 1.83-10.99), disability (odds ratio OR 4.80, 2.17-10.64), and patient-reported cognitive decline (OR 3.43, 1.19-9.94). Asymptomatic ICAS detected by TCD incidentally in hospital-based, stroke-free populations carries a substantial risk of symptomatic transition and subsequent adverse outcomes. These findings underscore the prognostic importance of identifying asymptomatic ICAS clinically and highlight the necessity for intensive vascular risk factor management in this under-recognized group to guide primary stroke prevention strategies.Data access statement:Data from this study are available and can be accessed upon request.