A clinical trial has found no significant differences between the use of carotid-artery stenting and carotid endarterectomy over a period of five years for the prevention of strokes in asymptomatic patients with serious narrowing of the carotid artery.
The results of the study, which has been called the most modern clinical trial on the subject by a Massachusetts General Hospital press release, have been published online in the New England Journal of Medicine to coincide with their presentation at the International Stroke Conference in Los Angeles.
“Our study showed that carotid-artery stenting is just as safe and just as effective in treating asymptomatic patients as carotid endarterectomy, which has been the standard treatment approach for patients who are not at high risk for open surgery,” says Kenneth Rosenfield, head of Vascular Medicine and Intervention at the Massachusetts General Hospital Division of Cardiology, lead and corresponding author of the NEJM report. “While a previous, major trial also found equivalent results for the two procedures, it was not able to determine whether that result applied to patients with asymptomatic carotid stenosis.”
A 2010 study (the Carotid Revascularization Endarterectomy versus Stenting Trial, CREST) found that both procedures had similar outcomes, although in the period immediately after the procedures there was a slightly higher risk of minor stroke with carotid-artery stenting and of heart attack with carotid endarterectomy. But, CREST examined patients both with and without prior symptoms of stroke and did not enroll enough asymptomatic participants to determine whether the results applied independently to those patients. The current study, called Asymptomatic Carotid Trial (ACT) I, was designed to investigate that specific question.
Conducted from 2005 to 2013 at 97 US centers, ACT I enrolled 1,453 participants aged 79 or less, all of whom had no stroke-related symptoms, despite having narrowing of from 70–99% of one carotid artery. Their diagnoses were confirmed by either ultrasound or angiogram, often after their physician had detected a bruit while listening to the carotid area with a stethoscope. Participants were randomly assigned to either carotid endarterectomy or carotid-artery stenting, and received a complete neurological assessment before and after the procedure; one, six and 12 months later; and then annually for up to five years.
A total of 1,089 patients received carotid stents, while 364 had carotid endarterectomy. In terms of the incidence of stroke, death or heart attack in the 30 days after the procedure, overall rates were very low—around 3.5% for each—and with no significant difference between the two groups. The long-term results also were very similar, with 97.3% of those in the stenting group and 97.8% in the endarterectomy group remaining free of stroke involving the treated side.
The authors note that treatment of carotid stenosis with medications only—platelet-blocking agents, statins and drugs to reduce blood pressure—has become more accepted in recent years. However, whether medical treatment alone outweighs the benefit of eliminating the blockage in asymptomatic patients has yet to be investigated. “We really do not know if patients with severe asymptomatic carotid-artery stenosis can be safely treated with medications only,” says study co-author Michael R Jaff, medical director of the MGH Fireman Vascular Center. “That is the outstanding remaining critical question.”
A follow-up to the CREST trial—called CREST 2—has been designed to investigate the role of stenting or endarterectomy versus intensive medical treatment alone in asymptomatic patients with severe carotid stenosis. Also important to investigate, adds Jaff—who is a professor of Medicine at Harvard Medical School and the Fireman chair in Vascular Medicine at MGH—will be methods of determining which procedure is best for a specific individual patient.