Progression of asymptomatic mild carotid artery stenosis: Implications for frequency of surveillance

Natural History of Asymptomatic Moderate Carotid Artery Stenosis in a Large Community-Based Cohort

Background:

Moderate carotid artery stenosis is a poorly defined risk factor for ischemic stroke. As such, practice recommendations are lacking. In this study, we describe the long-term risk of stroke in patients with moderate asymptomatic stenosis in an integrated health care system.

Methods:

All adult patients with asymptomatic moderate (50%–69%) internal carotid artery stenosis between 2008 and 2012 were identified, with follow-up through 2017. The primary outcome was acute ischemic stroke attributed to the ipsilateral carotid artery. Stroke rates were calculated using competing risk analysis. Secondary outcomes included disease progression, ipsilateral intervention, and long-term survival.

Results:

Overall, 11 614 arteries with moderate stenosis in 9803 patients were identified. Mean age was 74.2±9.9 years with 51.4% women. Mean follow-up was 5.1±2.9 years. There were 180 ipsilateral ischemic strokes (1.6%) identified (crude annual risk, 0.31% [95% CI, 0.21%–0.41%]), of which thirty-one (17.2%) underwent subsequent intervention. Controlling for death and intervention as competing risks, the cumulative incidence of stroke was 1.2% (95% CI, 1.0%–1.4%) at 5 years and 2.0% (95% CI, 1.7%–2.4%) at 10 years. Of identified strokes, 50 (27.8%) arteries had progressed to severe stenosis or occlusion. During follow-up, there were 17 029 carotid studies performed in 5951 patients, revealing stenosis progression in 1674 (14.4%) arteries, including 1614 (13.9%) progressing to severe stenosis and 60 (0.5%) to occlusion. The mean time to stenosis progression was 2.6±2.1 years. Carotid intervention occurred in 708 arteries (6.1%). Of these, 66.1% (468/708) had progressed to severe stenosis. The overall mortality rate was 44.5%, with 10.5% of patients lost to follow-up.

Conclusions:

In this community-based sample of patients with asymptomatic moderate internal carotid artery stenosis followed for an average of 5 years, the cumulative incidence of stroke is low out to 10 years. Future research is needed to optimize management strategies for this population.

Epidemiology of atherosclerotic carotid artery disease

Atherosclerotic carotid artery disease is a significant cause of stroke in the United States and globally. Its prevalence increases with age and it is more prevalent in men and White and Native-American populations. However, the outcomes related to carotid disease are worse in women and Black patients. Research suggests the disparities exist due to a multitude of factors, including disease pathophysiology, access to care, provider bias, and socioeconomic status. The prevalence of carotid stenosis in the general population is low (3%), and routine screening for carotid stenosis is not recommended in adults. Randomized clinical trials have shown benefits of stroke risk reduction with surgery (carotid endarterectomy or stenting) for symptomatic patients. Management is controversial in asymptomatic patients, as modern medical management has results equivalent to those of surgery and ongoing randomized clinical trials will address this important question. Carotid surgery is not appropriate in asymptomatic patients with limited life expectancy. Future work should explore comprehensive care models for care of patients with carotid disease and assessment of patient-reported outcomes to measure quality of care.

Differential rates of progression of low-grade carotid stenosis detected by follow-up ultrasound: A single institution experience

OBJECTIVES

The growing body of evidence suggesting that lifestyle changes and aggressive medical management reduce the risk of strokes in patients with carotid stenosis has fostered interest in noninvasive screening. The objective of this study was to develop recommendations for follow-up carotid ultrasound surveillance of patients with <60% carotid stenosis.

METHODS

This retrospective observational cohort study includes 2956 patients seen between August 1998 and March 2015 in 4440 visits. Data analysis was restricted to 7710 carotid ultrasounds. Primary outcome was progression of carotid stenosis as defined by the "bulb" method: baseline stenosis of 0%-39% progressed to 40%-59% on subsequent examination, baseline stenosis of 0%-39% progressed to ≥60%, or baseline of 40%-59% progressed to ≥60%. Progression was estimated using Cox proportional hazard ratios and the Kaplan-Meier method.

RESULTS

More than 10% of patients progressed in the 40%-59% baseline group within 12 months compared to 78 months for the 0%-39% baseline group. Patients who progressed had a higher proportion of peripheral vascular disease, and current/former smoking compared to those who did not. While there were statistically significant correlations between medication classes and comorbidities, none of the medications studied appeared to slow carotid stenosis progression.

CONCLUSIONS

In our experience, for patients with a 0%-39% carotid stenosis, follow-up examination should be performed at 6-year intervals. For patients with 40%-59% carotid stenosis, follow-up should be obtained annually to identify those who progress to a level requiring intervention. Future studies should examine whether study findings can be replicated using other approaches for determining carotid stenosis.

ECAS progression score: a web-based model to predict progression of extracranial carotid artery stenosis

BACKGROUND AND PURPOSE

To develop and validate a risk model (Extracranial Carotid Artery Stenosis progression score, ECAS-PS) and to predict risk of ECAS progression.

METHODS

The ECAS-PS was developed based on the Renqiu Stroke Screening Study (RSSS), in which eligible participants were randomly divided into derivation (60%) and validation (40%) cohorts. ECAS at baseline and follow-up was diagosed by carotid duplex ultrasound according to the published criteria. ECAS progression was defined as an increase in ECAS to≥50% for those with a baseline of <50% or as an increase to a higher category of stenosis if the baseline stenosis was ≥50%. Independent predictors of ECAS progression were obtained using multivariable logistic regression. The area under the receiver operating characteristic curve (AUROC) and the Hosmer-Lemeshow test were used to assess model discrimination and calibration.

RESULTS

A total of 4111 participants were included and the mean age was 64.3. A total number of 29 (0.7%), 24 (0.6%) and 48 (1.2%) patients progressed during 2-year follow-up for left, right and bilateral (either left or right) carotid artery, respectively. The ECAS-PS was developed from a set of predictors of ECAS progression. The ECAS-PS demonstrated good discrimination in both the derivation and validation cohorts (AUROC range: 0.824-0.917). The Hosmer-Lemeshow tests of ECAS progression score were not significant in the derivation and validation cohorts (all P > 0.05).

CONCLUSION

The ECAS progression score is a valid model for predicting the risk of ECAS progression. Further validation of the ECAS-PS in different populations and larger samples is warranted.