Stent versus surgery in carotid stenosis

In a study published in NEJM Rosenfield et al report the findings of a trial that compared carotid artery stenting with “embolic protection” to carotid endarterectomy.

In this trial, the authors compared carotid-artery stenting with “embolic protection” and carotid endarterectomy in 1453 patients who were 79 years of age or younger who had severe carotid stenosis and were asymptomatic.  Patients were followed for up to 5 years. The primary composite end point of death, stroke, or myocardial infarction within 30 days after the procedure or ipsilateral stroke within 1 year was tested at a non-inferiority margin of 3 percentage points.

The rate of stroke or death within 30 days was 2.9% in the stenting group and 1.7% in the endarterectomy group (P=0.33). From 30 days to 5 years after the procedure, the rate of freedom from ipsilateral stroke was 97.8% in the stenting group and 97.3% in the endarterectomy group (P=0.51), and the overall survival rates were 87.1% and 89.4%, respectively (P=0.21). The cumulative 5-year rate of stroke-free survival was 93.1% in the stenting group and 94.7% in the endarterectomy group (P=0.44).

The authors concluded that stenting was not inferior to endarterectomy with regard to the rate of the primary composite end point at 1 year. In analyses that included up to 5 years of follow-up, there were no significant differences between the study groups in the rates of non–procedure-related stroke, all stroke, and survival.

N Engl J Med 2016; 374:1011-1020

Carotid Occlusion May Not Be Associated With High Risk For Stroke

Yang et al published on JAMA Neurology their retrospective analysis of patients who presented at two atherosclerosis clinics in Ontario with asymptomatic carotid artery stenoses that were followed for 20-years with carotid duplex scans.

Among the 3681 patients who had annual carotid ultrasound examinations, 316 (8.6%) were asymptomatic before an occlusion that occurred during observation period.

Of the new occlusions, 254 of 316 [80.4%] occurred before 2002, when medical therapy was less intensive; the frequency decreased by quartile of years (P < .001, χ2 test). Only 1 patient (0.3%) had a stroke at the time of the occlusion, and only 3 patients (0.9%) had an ipsilateral stroke during follow-up (all before 2005).

In Kaplan-Meier survival analyses, neither severity of stenosis nor contralateral occlusion predicted the risk of ipsilateral stroke or transient ischemic attack, death from stroke, or death from unknown cause at a mean follow-up of 2.56 years. In Cox proportional hazards regression analyses, only age (P = .02), sex (P = .01), and carotid plaque burden (P = .006) significantly predicted risk of those events.

The authors concluded that the risk of progression to carotid occlusion is well below the risk of carotid stenting or endarterectomy and has decreased markedly with more intensive medical therapy. Preventing carotid occlusion is not  a valid indication for intervention to prevent occlusion as the circle of Willis offers substantial protection.

JAMA Neurol. 2015.1843

USPSTF Recommends Against Screening For Asymptomatic Carotid Artery Stenosis

Although stroke is a leading cause of death and disability in the United States, a relatively small proportion of all disabling strokes are due to Carotid Artery Stenosis (CAS).

The most commonly used screening test for severe CAS (60% to 99% stenosis) is duplex ultrasonography.  The accuracy of carotid duplex ultrasonography, by using digital subtraction angiography as the reference standard, estimate the sensitivity to be 86% to 90% and the specificity to be 87% to 94% for detecting CAS greater than 70%. The estimated sensitivity and specificity of carotid duplex ultrasonography to detect CAS of 60% or more are approximately 94% and 92%, respectively.  In 1996, the USPSTF reviewed the evidence for screening for bruits on physical examination and found that the test had poor reliability and poor sensitivity.  Good evidence indicates that duplex ultrasonography has moderate sensitivity and specificity but yields many false-positive results. A positive result on duplex ultrasonography is often confirmed by digital subtraction angiography, which is more accurate but is associated with complications. Given these facts, some people with a false-positive test results may receive unnecessary carotid endarterectomy surgery.

The evidence analyzed by the U.S. Preventive Services Task Force (USPSTF) indicates that in selected, high-risk trial participants with asymptomatic severe CAS, carotid endarterectomy by select surgeons reduces the 5-year absolute incidence of all strokes or peri-operative death by approximately 5%. These benefits would be less among asymptomatic people in the general population. For the general primary care population, the benefits are judged to be no greater than small.

Therefore evidence indicates that both the testing strategy and the treatment with carotid endarterectomy can cause harms. A testing strategy that includes angiography will itself cause some strokes. A testing strategy that does not include angiography will cause some strokes by leading to carotid endarterectomy in people who do not have severe CAS. In excellent centers, carotid endarterectomy is associated with a 30-day stroke or mortality rate of about 3%; some areas have higher rates. These harms are judged to be no less than small.

The U.S. Preventive Services Task Force concludes that for individuals with asymptomatic CAS there is moderate certainty that the benefits of screening do not outweigh the harms and its draft document gives a “D” recommendation.