Five-Year ACT-1 Data Show CAS as Effective as CEA for Stroke Prevention in Asymptomatic Patients


March 21, 2016—The 5-year findings from ACT 1, the Asymptomatic Carotid Trial, were published by Kenneth Rosenfield, MD, et al in The New England Journal of Medicine (2016;374:1011–1020). ACT 1 was funded by Abbott Vascular.

According to an announcement from Massachusetts General Hospital (MGH) in Boston, Massachusetts, the randomized ACT 1 trial is the most modern clinical trial to compare the use of carotid artery stenting (CAS) with carotid endarterectomy (CEA) for the prevention of strokes in asymptomatic carotid stenosis patients. The study found no significant differences in the outcomes between the two procedures over a period of up to 5 years.

In the MGH announcement, Dr. Rosenfield, who is Head of Vascular Medicine and Intervention in the MGH Division of Cardiology, commented, “Our study showed that CAS is just as safe and just as effective in treating asymptomatic patients as CEA, which has been the standard treatment approach for patients who are not at high risk for open surgery. 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.” 

Dr. Rosenfield and Jon Matsumura, MD, from the University of Wisconsin in Madison, Wisconsin, are Principal Investigators of the trial.

ACT 1 investigator Lawrence Wechsler, MD, presented the data at the American Heart Association’s 2016 International Stroke Conference, which was held February 17–19 in Los Angeles, California. Dr. Wechsler is from the University of Pittsburgh Medical Center in Pittsburgh, Pennsylvania.

As noted by MGH, the 2010 CREST (Carotid Revascularization Endarterectomy versus Stenting Trial) results showed 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 CEA.

However, CREST examined patients both with and without previous symptoms of stroke and did not enroll enough asymptomatic participants to determine whether the results applied independently to those patients. ACT 1 was designed to investigate that specific question.

The ACT 1 trial was conducted from 2005 to 2013 and enrolled 1,453 patients (age, ≤ 79 years) at 97 centers in the United States. All patients had 70% to 99% narrowing of one carotid artery, but no stroke-related symptoms.

In the trial, 1,089 patients received CAS and 364 patients received CEA. In terms of the incidence of stroke, death, or heart attack in the 30 days after the procedure, overall rates were very low—approximately 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 CAS group and 97.8% in the CEA group remaining free of stroke involving the treated side.

The investigators noted that treatment of carotid stenosis with medications has only become more accepted in recent years. However, it has yet to be investigated whether medical treatment alone outweighs the benefit of eliminating the blockage in asymptomatic patients.

ACT 1 Co-Investigator Michael R. Jaff, DO, medical director of the MGH Fireman Vascular Center, commented in the announcement, “We really do not know if patients with severe asymptomatic carotid artery stenosis can be safely treated with medications only. That is the outstanding, remaining critical question.” 

MGH advised that the role of CAS or CEA versus intensive medical treatment alone in asymptomatic patients with severe carotid stenosis will be investigated in the follow-up study, CREST 2.

Dr. Jaff also noted that it will be important to investigate methods of determining which procedure is best for a specific, individual patient, noted MGH.


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