CONTACT: Gian Galassi
(608) 263-5561
ggalassi@uwhealth.org
MADISON—Carotid artery stenosis, or the narrowing of blood vessels in the neck, is one of the leading causes of strokes in the United States. The gold standard for treating this condition is called carotid endarterectomy (CEA), an invasive surgical procedure that involves removing plaque buildup from the carotid artery through an incision in the neck.
But a new study published online Feb. 17 in the New England Journal of Medicine suggests that a less invasive procedure—carotid artery stenting (CAS) with embolic protection—is becoming a safer and similar treatment option for patients with asymptomatic severe carotid artery disease.
The CAS procedure involves a catheter being inserted in the femoral artery of the groin and guided via x-ray to the blocked artery in the neck, where a small balloon and a stent are inflated to reopen the vessel. Embolic protection devices work in tandem with stents to help support the newly opened artery and to catch any plaque that could break off during the process and cause a stroke.
“This is the largest randomized trial of its kind for asymptomatic patients and it will help guide the treatment for people with severe asymptomatic carotid stenosis,” said Dr. Jon Matsumura, co-first author and head of the vascular surgery division at University of Wisconsin School of Medicine and Public Health. “Technological advancement could improve treatment options for one of the leading causes of stroke in this country and trials like ACT I are necessary to determine the value of these advances. Ultimately, that’s great news for people suffering from carotid artery disease.”
The ACT I trial was a multicenter study that randomized 1,453 subjects 3:1 to each treatment arm (n=1089 for CAS and n=364 for CEA) between March 2005 and January 2013. Subjects were 80 years of age or younger with asymptomatic bifurcation carotid stenosis (between 70 and 99 percent blockage) and candidates for either CEA or CAS. All patients were considered standard risk for operative complications.
The study found CAS to be “non-inferior” to CEA based on a primary composite outcome, which combines the rates of death, stroke and myocardial infarction (DSMI) within 30 days, plus ipsilateral (same side of the body) stroke within one year into a single endpoint. Non-inferiority trials do not determine equivalency but instead seek to determine whether a new treatment is not worse than the standard treatment by more than an acceptable amount. For this study, the non-inferiority margin of the difference was tested at three percent, meaning the difference in adverse events of the primary composite outcomes between CAS and CEA had to be less than or equal to three percent. The study’s results are as follows:
Rates of DSMI within 30 days, plus ipsilateral stroke within one year, were 3.8 percent for CAS and 3.4 percent for CEA, resulting in a difference of 0.4 percent.
The 30-day death or major stroke rates were low in both groups (0.6 percent).
The 30-day minor stroke was higher for CAS (2.4 percent vs 1.1 percent).
One limitation of the ACT I study was the lack of a treatment arm that received medical therapy only. Since the study began more than a decade ago, advances in medical therapy have resulted in reduction in stroke risk for select populations with neurologic symptoms. Other trials are currently underway that will evaluate the relative benefit of medical intervention to CEA and CAS.
Medicare does not currently cover CAS for asymptomatic patients who are not enrolled in a clinical trial.
Stroke is the fifth- leading cause of death and the leading cause of disability in American adults, resulting in more than 170,000 deaths and causing major disability among survivors at a cost of approximately $41 billion annually. As many as 20 percent of the nearly 800,000 strokes that occur in the United States each year are a result of extra cranial carotid artery disease.
The ACT I study was funded by Abbott Vascular, which provided the stents and embolic protection devices used in the study and contributed to the statistical analysis. Dr. Matsumura and Dr. Kenneth Rosenfield, co-first author and section head for vascular medicine and intervention at Massachusetts General Hospital in Boston, both report receiving grant support and personal fees from Abbott Vascular during the conduct of the study.
