Five-Year ACST-2 Results Show Similar Long-Term Risk of Stroke for CEA and CAS

August 29, 2021—The European Society of Cardiology (ESC) announced findings from the ACST-2 trial comparing the long-term effect on stroke of carotid endarterectomy (CEA) versus carotid artery stenting (CAS) in asymptomatic patients with a severely narrowed carotid artery that had not yet caused a stroke. The trial demonstrated that CEA and CAS have comparable long-term effects on fatal or disabling stroke in these patients.

The ESC announcement stated that ACST-2 is the largest trial to compare the long-term effect of CAS versus CEA on stroke in this patient population.

Professor Alison Halliday, MD, who is Principal Investigator of the ACST-2 trial, commented in the ESC press release, “We have shown that for patients with a severely narrowed carotid artery, stenting and surgery have similar effects on the chances of having a disabling or fatal stroke. The risk from each procedure is about 1%. After that, however, the annual risk over the next 5 or more years is halved, from 1% down to 0.5% per year.”

The late-breaking ACST-2 data were presented in a Hot Line session at ESC Congress 2021, which was held virtually August 27-30. Simultaneous with the presentation, the trial findings were published online by Prof. Halliday et al in The Lancet.

As noted in the ESC announcement, patients with severe carotid artery stenosis are at elevated risk of stroke, and both CEA and CAS and can restore patency and reduce the long-term risk of stroke. Nationwide registry data from Germany have shown that among asymptomatic patients, CEA and CAS are both associated with an approximately 1% risk of disabling stroke or death; however, comparative data are lacking on the long-term protective effects of the two procedures.

ESC summarized that the ACST-2 trial enrolled 3,625 patients from 130 centers in 33 countries who had severe carotid artery narrowing (≥ 60% reduction in diameter on ultrasound) found by chance but with no recent stroke or other neurologic symptoms. The doctors of the enrolled patients thought that either CAS or CEA was needed, but both doctor and patient were substantially uncertain about which procedure was preferable.

Patients in the trial were randomly allocated 1:1 to CAS or CEA and followed-up for an average of 5 years. The main outcomes were procedural risks (morbidity and mortality within 1 month after the procedure) and, most importantly, nonprocedural stroke subdivided by severity.

The investigators found that in both groups, 1% of patients had a disabling stroke or died within 30 days (CAS, 15; CEA, 18), and 2% had a nondisabling procedural stroke (CAS, 48; CEA, 29).

For the main outcome of 5-year nonprocedural stroke risk, the investigators reported the following:

• Fatal or disabling stroke occurred similarly in CAS and CEA patients (2.5% vs 2.5%; rate ratio [RR], 0.98; 95% CI, 0.64-1.48; P = .91).
• Any nonprocedural stroke occurred more frequently in the CAS group (5.3% vs 4.5%; RR, 1.16; 95% CI. 0.86-1.57; P = .33).
• A meta-analysis of this and all other major trials of CAS versus CEA yielded a similarly nonsignificant result for any stroke (RR, 1.11; 95% CI, 0.91-1.32; P = .21).