Carotid Stenting at the Crossroads

Abstract

STROKE IS A MAJOR CAUSE OF DEATH AND DISABILITY. Approximately 10% to 15% of ischemic strokes are attributable to atherosclerosis of the internal carotid arteries, and there is great interest in surgical and endovascular approaches to stroke prevention. Carotid artery surgery or endarterectomy (CEA) has been the traditional intervention, and carotid angioplasty with stenting (CAS) is the newer percutaneous procedure. Both procedures increase the short-term risk of death or stroke due to the intervention in exchange for a lower long-term risk of stroke. Therefore, the magnitude and balance of the risks and benefits for these procedures are crucial considerations. Patients with symptomatic disease (ie, those who have had a stroke or transient ischemic attack in the past 6-12 months in the distribution of a carotid artery with 50% stenosis) benefit from CEA, which reduces the absolute risk of stroke by 8% per year. Asymptomatic patients (those with carotid occlusive disease without neurological symptoms) have a more modest benefit from CEA (absolute stroke reduction of 0.8%-1% per year). Carotid artery surgery or endarterectomy is considered beneficial only if it can be performed with a 30-day risk of death or stroke of 6% or less among symptomatic patients and 3% or less among those who are asymptomatic. Carotid angioplasty with stenting was originally approved by the US Food and Drug Administration (FDA) in 2004 for patients who were at too high a risk for CEA because of comorbidity or anatomical factors. In October 2004, because of uncertainty about efficacy, Medicare restricted reimbursement for CAS to high-risk symptomatic patients enrolled in postapproval studies. In March 2005, Medicare expanded coverage to allow treatment of high-risk symptomatic patients with carotid stenosis greater than 70% outside of trials using FDAapproved stents and embolic protection devices. The Centers for Medicare & Medicaid Services (CMS) also covers CAS for symptomatic patients with 50% to 70% carotid stenosis and asymptomatic patients with greater than 80% carotid stenosis if the procedure is performed in a postapproval or randomized controlled trial (RCT). Since then, CAS use has increased substantially, with large geographic variations in utilization. The Carotid Revascularization Endarterectomy vs Stenting Trial (CREST) compared CAS with CEA for patients with symptomatic and asymptomatic carotid disease. However, debate persists regarding interpretation of the study findings; CAS was equivalent to CEA for the primary composite end point of periprocedural death, stroke, or myocardial infarction or subsequent ipsilateral stroke. Carotid angioplasty with stenting was associated with worse outcomes than CEA for the combined outcome of periprocedural death or stroke or subsequent stroke, the end point used in trials comparing CEA with medical therapy. In May 2011, based on the CREST results, the FDA expanded the indication for CAS to all patients with carotid disease, not just those at high surgical risk. Against this backdrop, the outcomes and use of CAS in real-world practice is of great importance. In this issue of JAMA, Nallamothu and colleagues examine the relationship between operator experience and 30-day mortality rates following CAS using national Medicare administrative data from 24 701 procedures performed by 2339 physicians between 2005 and 2007. The authors found that patients treated by lowest-volume operators ( 6 CAS procedures per year) had an increased odds of death compared with patients treated by high-volume operators ( 24 procedures per year). Low-volume operators were much less likely to use an embolic protection device, an intervention associated with improved outcomes. They also demonstrated a “learning curve” at the individual physician level among the 1792 “later adopters” who started performing CAS after the 2005 CMS cov-