Impact of Technique and Device Selection on Clinical Outcomes in Carotid Artery Stenting

VASCULAR DISEASE MANAGEMENT 2010;7(2):E20 -E26

Introduction

Each year about 780,000 people experience a new or recurrent stroke, accounting for 17% of cardiovascular deaths.¹ Approximately 80% of strokes are caused by focal cerebral ischemia and the remaining 20% are caused by hemorrhage.² Almost 20% of ischemic strokes result from carotid artery stenosis.^3,4 Various options for the management of carotid artery stenosis include medical therapy, carotid artery endarterectomy (CEA) and carotid artery stenting (CAS). CEA has been established as a gold-standard treatment for carotid artery stenosis by randomized, controlled clinical trials^.5–8 CAS has emerged as an appropriate alternative therapy to surgery for carotid artery stenosis.

Background

The earliest reports on CEA were published in the 1950s,^9,10 and its superiority to medical management was established in the 1990s by four randomized trials which include NASCET⁵ (North American Symptomatic Carotid Endarterectomy Trial), ECST⁶ (European Carotid Surgery Trial), ACAS⁷ (Asymptomatic Carotid Atherosclerosis Study) and ACST⁸ (Asymptomatic Carotid Surgery Trial). The NASCET and ECST trials established CEA superiority to medical management in symptomatic patients. ACAS and ACST established in asymptomatic patients that CEA was superior to medical therapy for prevention of stroke. This led to the recognition of CEA as a gold-standard treatment for symptomatic and asymptomatic patients with severe carotid artery stenosis. However, a substantial limitation to the trial experience is the general population differs from the carefully selected patients in the above-mentioned trials. NASCET excluded patients with age >80 years or patients with multiple comorbid conditions.⁵ CAS has emerged as an alternative revascularization option after the initial experience from prospective single-center studies.^11,12 Multiple trials including CAVATAS¹³ (Carotid and Vertebral Artery Transluminal Angioplasty Study), Wallstent Trial¹⁴ and CaRESS¹⁵ (Carotid Revascularization Using Endarterectomy or Stenting Systems) provided developmental experience and guidance for successful CAS. The SAPPHIRE¹⁶ (Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy), a multicenter randomized trial established the noninferiority of CAS with embolic protection compared to CEA in high-risk patients. Subsequent to the promising results in high-risk patients, SPACE¹⁷ (Stent-supported Percutaneous Angioplasty of the Carotid artery versus Endarterectomy) trial was designed to address the optimal revascularization in low risk patients. This trial failed to enroll the required number of patients and remained inconclusive. The EVA-3518 (Endarterectomy Versus Angioplasty in Patients with Symptomatic Severe Carotid Stenosis), demonstrated a 30-day rate of any stroke or death to be significantly higher in the CAS group (9.6%) than the CEA group (3.9%) (p = 0.01). However, the use of embolic protection devices (EPD) was not mandatory early in the trial. Patients treated without EPD experienced a 25% 30-day rate of stroke or death. This lead to protocol changes by the EVA-3S safety committee and the use of EPD was made mandatory. In addition, the physicians participating in EVA-3S had unequal experience. Surgeons performing CEA had to have performed at least 25 endarterectomies in the past year before trial entry, while endovascular physicians were allowed to perform stenting after completing 5–12 CAS procedures. Multiple CAS pilot trials and registries (Figure 1)^{15,16,18–32} for patients with high risk for CEA have demonstrated low rates of stroke and death. Therefore, it is difficult to accept higher complication rates in EVA-3S as outcomes in general CAS practice. The results of EVA- 3S with high CVA rates emphasized the importance of EPD in CAS as well as rigorous training for CAS physicians. The role of CAS in the management of carotid artery stenosis is evolving and improving. CAS outcomes are directly affected by patient characteristics, vascular anatomy, operator’s skill, device selection and the technique. In this review, we will discuss them briefly.

Carotid Artery Stenting Techniques and Device Selection

Patient selection. A careful selection of appropriate patients for CAS is of utmost importance. It involves a comprehensive approach, which includes a thorough history and physical examination, along with diagnostic data including duplex ultrasonography combined with either computed tomography angiography (CTA) or magnetic resonance angiography (MRA). Several factors in patient selection have been documented to affect the outcomes of CAS including clinical status (symptomatic vs. asymptomatic), age and lesion characteristics. The symptomatic clinical status carries a high risk of recurrent stroke in medically treated patients5 and the same holds true for periprocedural outcomes in CAS. Gray et al³² showed that the incidence of stroke, myocardial infarction (MI) and death at 30 days is higher in symptomatic (5.3%) versus asymptomatic (2.9%) patients aged

Conclusion

Carotid artery stenting can be performed with an acceptable low risk of periprocedural complications compared to CEA for high-risk patients. A careful selection of patients, suitable anatomy, adequate operator experience, and individualized selection of devices for the procedure are keys to a successful CAS procedure. A tailored approach toward each case ensures a low periprocedural risk of stroke and death. The advancing technology with improved EDP devices and stent design are promising, and will hopefully translate into better clinical outcomes in the future.

From the *Cardiology Department, Hahnemann Hospital/Drexel University College of Medicine, Philadelphia, Pennsylvania; §Abington Memorial Hospital, Abington, Pennslyvania; and £Covenant Healthcare, Saginaw, Michigan.

The authors report no conflicts of interest regarding the content herein.

Address for correspondence: Daniel J. McCormick, DO, Director, Cardiac Catheterization Laboratory, Cardiology Department, Hahnemann Hospital/Drexel University College of Medicine, Broad and Vine Street, Philadelphia, PA 19102. E-mail: dandoc49@aol.com