Early results from ACST-2 suggest that modern carotid artery stenting and carotid endarterectomy have a low serious morbidity and mortality, according to early results of the Asymptomatic Carotid Surgery Trial 2 (ACST-2).
Blinded early results in the first 691 patients enrolled in the study were presented by Alison Halliday, University of Oxford, Oxford, UK, at the European Society for Vascular Surgery (ESVS) Annual Meeting in Bologna, Italy, on behalf of the ACST-2 investigators.
ACST-1, conducted between 1993 and 2008, randomised 3,120 patients with tight asymptomatic carotid stenosis to medical treatment alone or medical treatment plus carotid endarterectomy. The results, Halliday noted, showed that carotid endarterectomy reduced subsequent stroke risk by 50%, and that this benefit was maintained to 10 years. “As a result of that, surgery for men and women under 75 years reduces the 10-year stroke risk, with an absolute reduction by 6%. And the same absolute benefit from surgery (6%) was seen in patients who were on statin at that time,” she said.
Halliday stated that over 250,000 carotid interventions are performed worldwide every year, with a great variation in the proportion of asymptomatic patients and type of procedure in the USA, Europe and the UK. “It means that there is much uncertainty on whether to choose carotid endarterectomy or stenting,” she said.
She added, “Worldwide during the 2010s, millions of asymptomatic patients will have a carotid procedure. ACST-2 hopes to randomise 5,000 patients to reliably assess the early- and long-term efficacy of carotid stenting vs. endarterectomy. The principle is that when an intervention is clearly needed and both procedures are thought to be appropriate, physicians consider randomising patients into ACST-2. One thousand people have already been recruited in 24 countries and we are making a good progress.”
In the first 1,000 patients enrolled in the trial, the median age was somewhat higher than in ACST-1 and almost all patients had 70–99% stenosis. Halliday pointed out that there has been a rise in the number of diabetic patients randomised in this trial. At trial entry, 90% were on anti-thrombotic drugs, 79% were taking anti-hypertensive medication and 75% were on statins.
Halliday presented blinded early results in the first 700 patients with one month follow-up and a subsequent six month Rankin score for any stroke. Eight types of stent and eight types of cerebral protection devices were utilised in the patients having CAS. The most frequent stent used was the Wallstent (Boston Scientific), and about half of the stents used were tapered devices.
Halliday told delegates that results by procedure were not available, only the overall results. The death and disabling stroke rate was 1%. “In ACST-1 we had a 1.7% rate of death and disabling strokes with endarterectomy alone. These are different patients, at a different time, but intervention does not appear to be more harmful,” she said. The ACST-2 trial is not a study comparing surgery with no intervention, but is comparing 2 different interventions where they are though to be definitely needed. Patients in ACST-2 could therefore be considered to be those at significant risk of stroke within the next 10 years, and this is the main reason why intervention is being undertaken.
Halliday stated that the ACST-2 Data Monitoring Committee commended the investigators on progress to date and on the recent increase in recruitment, and “urged the ACST-2 group to substantially increase the rate of patient recruitment while maintaining close long-term follow-up of all cases in this important trial.” She added: “The UK National Institute for Health and Clinical Excellence (NICE) has issued guidance on carotid stenting for asymptomatic patients in April 2011 and they encouraged clinicians either to enter patients into the ACST-2 trial or to submit data to the Endovascular Carotid Register.”
“So if you have a patient with 70–99% carotid stenosis but no recent symptoms and you are uncertain that a carotid procedure should be done, please consider a trial with a no-procedure control such as SPACE-2 and ECST-2. On the other hand, if you are certain that intervention should be undertaken, please consider ACST-2,” Halliday added.
“Reliable randomised evidence produces rapid and uniform changes in clinical practice. ACST-1 and 2 trial collaborators have now randomised more than 4,000 patients. Together, ACST-2, ECST-2 and SPACE-2 can improve the evidence and help our future patients to have the best treatment,” she said.