Background: Angioplasty is the recommended treatment for patients who have substantial stenosis of a carotid artery and high risk of stroke. Recently, carotid artery stenting has been advocated as an alternative treatment to endarterectomy. A Cochrane systematic review concluded that the 30-day safety outcomes of the two treatments did not differ significantly, but that large, well-designed clinical trials were needed. The SPACE (Stent-supported Percutaneous Angioplasty of the Carotid Artery versus End-arterectomy) trial was designed to compare carotid endarterectomy and carotid artery stenting for severe symptomatic carotid artery stenosis.
The Study: The international study enrolled 1,200 patients at 35 centers. The two groups were comparable in important variables. The average age was 68 years; 28 percent were women; and the distributions of stenosis severity, qualifying events, and comorbidities were similar between the two groups. The two criteria for inclusion in the study were serious neurologic or ocular symptoms (e.g., stroke, hemispheric transient ischemic attack, amaurosis fugax) within the previous 180 days, and at least 70 percent stenosis in the ipsilateral carotid artery on duplex ultrasonography.
Patients assigned to stenting had to be given 100 mg aspirin plus 75 mg clopidogrel (Plavix) daily for at least three days before and for 30 days after the procedure. Those allocated to endarterectomy had to be given at least 100 mg aspirin before, during, and after surgery. All patients were examined by a neurologist before the intervention; one day later; and after seven days, 30 days, six months, one year, and two years. The primary outcome was ipsilateral stroke or death from any cause within 30 days of intervention. Other end points included disabling ipsilateral stroke, any stroke within 30 days of treatment, procedure failure including residual stenosis of 50 percent or more, or any suspected adverse effect of treatment.
Results: Of the 605 patients assigned to stenting, 567 received the treatment. In the endarterectomy group, 565 of 595 patients underwent the procedure. Within 30 days of stenting, the rate of stroke or death was 6.84 percent compared with 6.34 percent following endarterectomy. Per-protocol analysis showed no significant difference between the two treatments in the primary outcome. Four deaths occurred in the stenting group and five in the endarterectomy group. The rates of stroke with symptoms lasting longer than 24 hours and death from any cause did not differ significantly between the groups. The groups also were equivalent in rates of inability to treat the stenosis, residual stenosis of 50 percent or more, and other secondary end points. For both procedures, results were worse for patients older than 75 years and for women. Endarterectomy had slightly better results in older patients and women, but the difference was not statistically significant.
Conclusion: The authors conclude that the two procedures are similar in all measured outcomes. Although larger trials with longer follow-up are needed, the study failed to demonstrate any outcomes or trends indicating that stenting is safer or that it provides any significant advantage over endarterectomy.
editor's note: A study conducted in U.S. veterans also reported no significant differences between conventional endarterectomy and stenting.1 The study compared 46 stent and 48 endarterectomy patients for outcomes including progression to critical restenosis, repeat surgeries, subsequent symptoms or stroke, and mortality. The researchers also reported equivalent changes in carotid artery velocity for up to 24 months of follow-up.—A.D.W.