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ACST-2 - Second asymptomatic carotid surgery trial: a randomized comparison of carotid artery stenting versus carotid endarterectomy

Project objectives

In patients with severe carotid artery stenosis, stentinging artery disease (CAS) and carotid endarterectomy (CEA) both carry procedural risks, which are approximately double for symptomatic patients compared to asymptomatic, but can restore patency and approximately halve long-term stroke rates in patients asymptomatic. Procedural risks have decreased over the decades, but there is still about a 1% risk of disabling stroke or death. There is also some procedural risk of nondisabling stroke (particularly with CAS) or nonfatal myocardial infarction or cranial nerve palsies (particularly with CEA). Modern drug therapy can also reduce stroke rates, but even with it, patients with severe carotid stenosis may have about a 1% per year risk of disabling stroke or death. So, in addition to good medical therapy, carotid procedures are still considered appropriate for many patients. However, there is often uncertainty as to whether CAS or CEA is more appropriate. Previous studies, first among symptomatic patients and then among asymptomatic patients, have directly compared CAS vs. CEA. Particularly for asymptomatic patients, however, randomized numbers have been limited, as shown by the 2020 Cochrane review led by LHB (which sets out the search strategy for such studies used in this report). The purpose of this study was to randomly assign a substantial number of asymptomatic patients and then to consider the results in the context of those of all other studies of CAS versus CEA.

Added value of this study: ACST-2 randomly assigned 3625 asymptomatic patients with severe carotid stenosis to CAS or CEA with good compliance and, thus far, an average of 5 years of follow-up. Each of the procedures carried a 1% risk of causing disabling stroke or death, but, after each, the annual rate of disabling or fatal stroke was only about 0,5%. This study more than doubled the number of asymptomatic patients in trials of CAS versus CEA. However, the randomized evidence from both asymptomatic and symptomatic patients is relevant to any comparison of the two procedures. By including the ACST-2, there is now as much evidence among asymptomatic patients as among symptomatic patients, and the outcomes in both types of patients are remarkably similar, with CAS as effective as CEA in reducing annual stroke risk, at least for the first years.

Implications of all available evidence - The trials of CAS versus CEA now provide better evidence than previously existed that both procedures pose similar risks and provide comparable benefits. This does not address the question of whether, in addition to good medical therapy, skillful carotid artery surgery would be appropriate, nor does it address the question of how much each procedure costs health services or patients. This does mean, however, that doctors and patients can more freely choose which procedure is most appropriate for individuals.

The aim of the new analysis is to evaluate the restenosis rates during the follow-up of the patients enrolled in the trial.

Start and end date

January 2008 - December 2020

Project Manager

Prof. Francesco Stilo, Head of Research Unit and Prof. Francesco Spinelli, UOC Director

Coordinating institution of the project

University Polyclinic Foundation Campus Bio-Medico

Other institutions involved in the project

  • GEMELLI IRCCS UNIVERSITY POLICLINICAL FOUNDATION
  • SAN DONATO POLICLINIC, MILAN
  • UNIVERSITY HOSPITAL OF BOLOGNA, BOLOGNA
  • UNIVERSITY HOSPITAL OF BARI, BARI
  • UNIVERSITY HOSPITAL OF PERUGIA
  • UNIVERSITY OF INSUBRIA, VARESE
  • IRCCS HUMANITAS CLINICAL INSTITUTE
  • UNIVERSITY LA SAPIENZA
  • ST ANNA UNIVERSITY HOSPITAL, FERRARA
  • SAN CAMILLO FORLANINI, ROME
  • SAN GIACOMO HOSPITAL, CASTELFRANCO VENETO
  • SAN GIOVANNI DIO HOSPITAL, FLORENCE 
  • IRCCS SAN MATTEO POLICLINIC, PAVIA
  • SANTA MARIA ALLA SCOTTE POLICLINIC, SIENA
  • IRCCS SAN MARTINO, GENOA
  • KENT AND CANTERBURY HOSPITAL, KENT
  • MANCHESTER UNIVERSITY HOSPITALS FOUNDATION TRUST
  • THE ROYAL PRESTON HOSPITAL, PRESTON (
  • WALTON CENTRE, LIVERPOOL
  • ST MARY'S HOSPITAL, LONDON
  • CARDIOVASCULAR CENTAR DEDINJE, BELGRAD
  • UNIVERSITY MEDICAL CENTER HAMBURG-EPPENDORF
  • UNIVERSITY HOSPITAL OF JENA, JENA
  • UNIVERSITÄTSKLINIKUM LEIPZIG/PARK HOSPITAL, LEIPZIG
  • UNIVERSITY HOSPITAL, TECHNICAL UNIVERSITY OF MUNICH
  • STÄDTISCHES KLINIKUM KARLSRUHE
  • UNIVERSITÄTSMEDIZIN MANNHEIM
  • OTHER INSTITUTIONS IN EU, UK, CHINA AND CANADA

Project funding source

Medical Research Council (MRC), the British Heart Foundation, and Cancer Research UK for the University of Oxford's NDPH, and received grants from the BUPA Foundation (BUPAF/33a/05) and National Institute for Health Research Health Technology Assessment program (HTA06/ 301/233) until 2013.
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