Carotid stenting noninferior to surgery for asymptomatic patients

By Eleanor McDermid

The findings of the ACT 1 trial suggest that carotid artery stenting (CAS) is just as effective as carotid endarterectomy (CEA) in patients with asymptomatic stenosis.

ACT (Asymptomatic Carotid Trial) 1 included patients who were younger than 80 years, had 70% to 99% carotid stenosis and were at standard risk of operative complications.

All patients were asymptomatic; in this ACT 1 was designed to complement CREST (Carotid Revascularization Endarterectomy vs Stenting Trial), which included both symptomatic and asymptomatic patients.

In all, 3.4% of 364 patients randomly assigned to undergo CEA had a stroke or myocardial infarction or died within 30 days of intervention, or had an ipsilateral stroke during the first year. This endpoint also occurred in 3.8% of the 1089 patients in the CAS group, and the upper confidence of the 95% confidence interval for the difference between the two groups was 2.27 percentage points, which was within the prespecified 3.0 percentage point noninferiority margin.

After long-term follow-up, the estimated 5-year survival rates were 87.1% and 89.4% for the CAS and CEA groups, respectively, Lawrence Wechsler (University of Pittsburgh Medical Center, Philadelphia, USA) reported at the International Stroke Conference in Los Angeles, California, USA.

The corresponding rates of freedom from ipsilateral stroke were 97.8% and 97.3%.

The findings are simultaneously released in The New England Journal of Medicine, where the researchers write: "It is widely recognized that the skill and experience of the physician is important in achieving acceptable outcomes both with endarterectomy and with stenting, particularly in asymptomatic patients, for whom the absolute risk reduction associated with the intervention is small."

In this vein, they note that ACT 1 "was designed and began enrollment a decade ago", and so lacks a control group given current best standard medical therapy. The annual stroke risk among asymptomatic patients in the current medical era "is probably less than 1% per year", they add.

The CREST 2 investigators are hoping to settle this question with two parallel studies testing CAS or CEA versus best medical management in asymptomatic patients; the trial has an estimated completion date at the end of 2020, although ACT 1 was halted at 88% recruitment because of slow enrolment.

But even for symptomatic patients it has been argued that optimal medical therapy might now compare favourably to surgical intervention or stenting.

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