Incidence of Ischemic Stroke in Patients With Asymptomatic Severe Carotid Stenosis Without Surgical Intervention

Abstract

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.

Figure 1.. Identification of Carotid Arteries With Asymptomatic Severe Stenosis, 2008-2012

Figure 2.. Cumulative Risk of Ipsilateral Ischemic Stroke per Unique Artery After Initial Diagnosis of Asymptomatic Severe Carotid Stenosis

Competing risks model comprises death and carotid intervention. Median observation time was 1.7 (IQR, 0.2-6.1) years.

Figure 3.. Per-Patient Medication Use, Adherence, and Effect Over Time

Data are reported for baseline (year 0) and for the next 7 years. In panels B and D, the horizontal bar in each box indicates the median, box tops and bottoms indicate the interquartile range, and the whiskers indicate the minimum and maximum (full range) values. BP indicates blood pressure, and LDL indicates low-density lipoprotein.