A look at surgical procedures in patients with carotid artery stenosis: The second asymptomatic carotid trial (ACST-2)

A look at surgical procedures in patients with carotid artery stenosis: The second asymptomatic carotid trial (ACST-2)

1500 1000 Akshar Patel

Carotid artery stenting (CAS) and carotid endarterectomy (CEA) are procedures that can restore patency and reduce the long-term risk of stroke. Both CAS and CEA have become common procedures in patients to prevent recurrent strokes in symptomatic patients and for primary stroke prevention in asymptomatic patients with severe carotid artery stenosis. Both CAS and CEA carry a short-term risk of stroke, which is about twice as great for symptomatic as for asymptomatic patients. Large registries and randomised trials of CAS versus CEA have suggested similar long-term protective effects of both procedures, largely in symptomatic patients. Halliday et al. conducted a large, randomised trial to provide more robust comparison of CAS versus CEA long-term protective effects in asymptomatic patients. This trial compared the 30-day hazards of non-procedural stroke and mortality in both procedures, and their stroke rates over the following 5 years.


No major differences were identified between either treatment groups

During the analysis of the results, there were very few differences identified between the CAS group and CEA group. One of the expected differences was the non-disabling procedural stroke rate, which was slightly increased in the CAS treatment group (5.2%) compared to the CEA treatment group (4.5%). This was not a surprising result as prior trials and national registry data sets have had similar outcomes. Subdivision of the overall non-procedural stroke results by baseline characteristics showed no significant evidence of heterogeneity of the treatment effect with respect to age, sex, stenosis and other factors. Long-term medical care was similar in both groups, and it generally involved antithrombotic, antihypertensive and lipid-lowering therapy.


Patient-specific factors should determine the surgical procedure to be used

The main outcomes of the trial were procedural mortality and morbidity, and non-procedural stroke within 30 days after the intervention. The ACST-2 trial showed there was no significant difference in the overall risk of death or disabling stroke in the short-term in CAS (1.0%) versus CEA (0.9%). After a mean of 5-year follow-up, non-procedural stroke was 2.5% in both groups for fatal or disabling stroke, and 5.2% with CAS versus 4.5% with CEA for any stroke. Halliday et al. concluded that serious complications were similar in both the CAS and CEA treatment groups, and the long-term effects on fatal or disabling stroke were comparable. The optimal treatment choice for patients maybe based on exclusion criteria for either of the procedures since short-term results are similar. Patients with calcification in the artery or tortuosity should avoid CAS and patients with high procedural risk, such as recent myocardial infarction, or cardiac emboli, should avoid CEA.


Short-term answers or long-term solutions?

The main finding of this trial of CAS versus CEA is that the effects of the two procedures on fatal or disabling events are approximately equal in terms of 30-day hazards and of 5-year disabling stroke rates. Prior randomised evidence and national registries showed similar protective value in both CAS and CEA in symptomatic patients. The ACST-2 trial supports those earlier findings, while also showing evidence in patients with asymptomatic disease. This study shows that CAS and CEA are similar for at least the first few years in their protective effects. Further follow-up of ACST-2 and other trial participants is needed to provide additional evidence on the longevity of their protective effects.


  1. Halliday A et al. Lancet. 2021;398:1065–1073.



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