Performing successful carotid endarterectomy (CEA) in patients younger than 75 years of age reduces 10-year stroke risk—half of which is a reduction in disabling or fatal stroke, according to the results of the ACST-1 trial published in the Sept. 25 issue of the Lancet. In a complementary meta-analysis in the same issue of Lancet, researchers found that carotid artery stenting (CAS) may be as safe as CEA in patients under 70.
Alison Halliday, MS, FRCS, of the John Radcliffe Hospital in Oxford, U.K., and colleagues conducted the ACST-1 (Asymptomatic Carotid Surgery Trial 1) to evaluate the long-term effects of successful CEA in 3,120 patients at 126 centers in 30 countries between April 1993 and July 2003.
The patients were randomized to either immediate CEA (n=1,560) or to indefinite deferral of any carotid procedure (n=1,560) and were followed up until death or for a median of nine years for survivors.
The authors used perioperative mortality and morbidity and non-perioperative stroke as the trial's primary endpoints.
Of the patients randomized to deferral, 26 percent (n=407) underwent CEA within 10 years. The authors noted that an estimated one-third of these patients eventually would have undergone CEA if they had survived.
The authors reported the rate of perioperative risk of stroke or death within 30 days to be 3 percent, which included 26 non-disabling strokes and 34 disabling or fatal perioperative events in 1,979 CEA procedures.
Additionally, the five-year stroke risk was reported to be 4.1 percent versus 10 percent for immediate CEA and deferred CEA, respectively—these rates excluded perioperative events and non-stroke mortality. At 10 years, rates of stroke were 10.8 percent and 16.9 percent, respectively.
While 62 patients who underwent CEA experienced a disabling or fatal stroke, 104 patients in the deferred arm experienced the same. For non-disabling stroke, these events occurred in 37 patients in the immediate CEA group compared to 84 in the deferred group.
When the authors combined the rates of perioperative events and stroke, the net risks were reported to be 6.9 percent and 10.9 percent for patients in the immediate CEA group and deferred group, respectively (at five years). These same rates at 10 years were 13.4 percent versus 17.9 percent, respectively.
The authors said that medication administration was similar in both groups; however, use of lipid-lowering drugs increased from 10 percent to over 80 percent during the duration of the trial. Additionally, benefits were shown in men and women up to 75 years of age at enrollment. Over half (166/287) died of or were disabled by stroke during the study.
“Calculations of the cost-effectiveness of CEA and of the number of patients that need to be treated to avoid one stroke should consider separately patients with short life expectancy and those with more than 10 years of reasonable life expectancy, because the potential long-term benefits of CEA are sharply curtailed in those who have less than 10 years of life expectancy,” the authors wrote.
The authors noted that the absolute 10-year stroke reduction would be an estimated 5 percent in patients on effective antihypertensives, antithrombotics or lipid-lowering therapy and who had little risk of death from other causes within 10 years. Twenty patients would need to be treated in order to avoid one incidence of stroke.
However, non-compliance could reduce this number to 15, the authors said. This was based on data that showed 92 percent of patients underwent early CEA and at year five, 16 percent allocated deferral and instead underwent elective CEA.
“Hence, the Kaplan-Meier estimates of the differences in 10-year outcomes between those allocated immediate CEA and those allocated deferral indicate the differences in 10-year outcomes that could be expected from operating before symptom onset on only about three-quarters (92 percent minus 16 percent) of patients allocated immediate CEA and on none of those allocated deferral,” the authors wrote.
While the authors noted that in patients older than 75, little net benefit might be seen from CEA, healthy men and women under the age of 75 could benefit from the procedures, “as long as perioperative risks remain low."
A meta-analysis published in the Sept. 25 issue of the Lancet and conducted by the Carotid Stenting Trialists Collaboration, compared three randomized controlled trials—EVA-3S, SPACE and ICSS—to assess whether or not carotid