Background: Carotid artery stenosis causes about 20 percent of strokes in adults. The current treatment is carotid endarterectomy, which has been shown to reduce the risk of stroke and death more effectively than medical therapy. Recently, carotid artery stenting has emerged as a newer and less invasive alternative. Results from studies comparing carotid stenting with endarterectomy have been ambiguous. Meier and colleagues evaluated the periprocedural safety and intermediate-term effectiveness of carotid artery stenting versus carotid endarterectomy in patients with carotid stenosis with or without symptoms.

The Study: This systematic review and meta-analysis included randomized controlled trials that directly compared carotid endarterectomy with carotid artery stenting. Inclusion criteria consisted of having stroke, death, or both as end points, and having at least 30 days of followup. Studies were evaluated for randomization, allocation concealment, intention-to-treat analysis, blinding, premature stopping of patient enrollment, and reporting of dropouts. A total of 11 studies (4,796 patients) were included. Ten studies looked at periprocedural outcomes (less than 30 days), and nine looked at intermediate-term outcomes (one to four years). The primary end point was a composite of mortality or stroke. Secondary end points were death, stroke, myocardial infarction, facial neuropathy, and a composite of mortality or disabling stroke.

Results: In the periprocedural time frame, the weighted average incidence of death or stroke was 5.4 percent for carotid endarterectomy and 7.3 percent for carotid stenting (odds ratio = 0.67). The difference was attributed mainly to a decreased risk of stroke. Risk of death separately and risk of composite death or disabling stroke were not significantly different. Cumulative meta-analysis revealed a change over time in the effectiveness of the procedures. Early studies showed that carotid endarterectomy was superior to stenting, but when newer trials were added sequentially, the differences in outcomes between the procedures decreased.

Periprocedural myocardial infarction and facial nerve injury occurred at higher rates in the carotid endarterectomy group. Four studies reported rates of infarction: weighted averages were 2.6 percent for carotid endarterectomy versus 0.9 percent for stenting. Six trials assessed periprocedural facial nerve injury. The weighted average incidence was 7.5 percent for endarterectomy versus 0.45 percent for stenting.

Regarding intermediate-term outcomes, there was no significant difference between carotid endarterectomy and carotid stenting in the primary end point of composite death or stroke.

Conclusion: The authors conclude that carotid endarterectomy is associated with a lower risk of death or stroke than is stenting in the periprocedural period, but especially a lower risk of nondisabling stroke. In this study, there were no differences in intermediate-term outcomes. Patients with symptoms requiring carotid revascularization should first be offered endarterectomy, and stenting should be reserved for those at high surgical risk. More trials comparing contemporary stenting and endarterectomy are needed.

editor's note: An accompanying editorial discusses the effectiveness of stenting in patients with asymptomatic carotid stenosis.¹ Globally, more carotid artery stenting and carotid endarterectomies are done in patients who are asymptomatic than in those who have symptoms. Results from large registries indicate that stenting is associated with a 2.4 to 3.4 percent risk of short-term stroke and death in patients younger than 80 years. These figures suggest that stenting might be more appropriate than endarterectomy in asymptomatic patients.¹ For asymptomatic patients being treated with endarterectomy, the absolute risk reduction for stroke during the next five years is 6 percent.² However, a procedural risk of stroke or death greater than 3 percent outweighs this benefit.

The editorial also notes that a learning curve exists for stenting.¹ A consensus panel of European stenting specialists concluded that a physician needs to have performed at least 150 procedures before being considered a safe operator. Earlier trials included in the study by Meier and colleagues compared less experienced with more experienced operators. Results of stenting have improved over time, but current recommendations are that stenting should be performed only by experienced operators.—j.a.k. and sumi sexton, Associate Editor, American Family Physician