Key PointsQuestion
What is the stroke rate in patients with asymptomatic severe carotid stenosis without surgical intervention?
Findings
This retrospective cohort study included 3737 participants with 70% to 99% asymptomatic carotid stenosis identified between 2008 and 2012 and followed-up through 2019 who did not undergo surgical intervention. The estimated rate of ipsilateral carotid-related acute ischemic stroke was 4.7% over 5 years.
Meaning
These findings may inform decision-making regarding treatment for patients with asymptomatic severe carotid stenosis.
Importance
Optimal management of patients with asymptomatic severe carotid stenosis is uncertain, due to advances in medical care and a lack of contemporary data comparing medical and surgical treatment.
Objective
To estimate stroke outcomes among patients with medically treated asymptomatic severe carotid stenosis who did not undergo surgical intervention.
Design, Setting, and Participants
Retrospective cohort study that included 3737 adult participants with asymptomatic severe (70%-99%) carotid stenosis diagnosed between 2008 and 2012 and no prior intervention or ipsilateral neurologic event in the prior 6 months. Participants received follow-up through 2019, and all were members of an integrated US regional health system serving 4.5 million members.
Exposures
Imaging diagnosis of asymptomatic carotid stenosis of 70% to 99%.
Main Outcomes and Measures
Occurrence of ipsilateral carotid-related acute ischemic stroke. Censoring occurred with death, disenrollment, or ipsilateral intervention.
Results
Among 94 822 patients with qualifying imaging studies, 4230 arteries in 3737 (mean age, 73.8 [SD 9.5 years]; 57.4% male) patients met selection criteria including 2539 arteries in 2314 patients who never received intervention. The mean follow-up in this cohort was 4.1 years (SD 3.6 years). Prior to any intervention, there were 133 ipsilateral strokes with a mean annual stroke rate of 0.9% (95% confidence interval [CI], 0.7%-1.2%). The Kaplan-Meier estimate of ipsilateral stroke by 5 years was 4.7% (95% CI, 3.9%-5.7%).
Conclusions and Relevance
In a community-based cohort of patients with asymptomatic severe carotid stenosis who did not undergo surgical intervention, the estimated rate of ipsilateral carotid-related acute ischemic stroke was 4.7% over 5 years. These findings may inform decision-making regarding surgical and medical treatment for patients with asymptomatic severe carotid artery stenosis.