Cerebral embolic protection devices and percutaneous carotid artery stenting.

Abstract

Ancient Greek physicians named the principal arteries of the neck as the carotid arteries as they believed that pressing hard on these arteries made mammals and humans become sleepy or lose consciousness (Karotides Greek, the arteries of the neck vkaros heavy sleep vkaroun to choke, to stupefy). The carotid artery bifurcation is the most common location of craniocervical atheromatous disease, which may induce brain ischaemia or be a source of thromboembolic material, accounting for 20–30% of strokes. The current indication for revascularization of carotid stenosis is prevention of stroke, and therefore, it is clear that the risk of the procedure has to be smaller than the clinical benefit rendered. Thus, individualized assessment of the risk–benefit ratio is heavily affected by both the initial risk (i.e. death or stroke rate) associated with the procedure and the natural history of the atherosclerotic carotid disease treated conservatively. Several prospective, randomized trials (1–6) have supported the benefit of carotid endarterectomy (CEA) over medical therapy for the treatment of significant obstructive carotid lesions. Since its introduction half a century ago, CEA has become one of the most commonly performed peripheral vascular procedures. Importantly, the benefit of CEA has been directly related to the severity of stenosis (3,7) and the projected benefit is clinically justified only if CEA can be performed with a risk of post-procedural death or disabling stroke of less than 6% for symptomatic patients and 3% for asymptomatic patients. When an inappropriately high complication rate occurs the clinical benefit is markedly impeded, thereby questioning the performance of CEA under those circumstances (7,8). Therefore, there is a rationale for exploring alternative revascularization techniques in patients considered at high surgical risk for periprocedural events. Accordingly, the 30-day rate of death or disabling stroke rate has been proposed to be a unifying standard for the evaluation of the postprocedural risk (9), that can be used to compare horizontally different revascularization methods. The 30-day rate of death or disabling stroke was 5.8% in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) (2) and 7.1% rate in the European Carotid Surgery Trial (ECST) trial (6). In this context, carotid artery stenting (CAS) as a new method that achieves percutaneous carotid artery revascularization should first be evaluated with respect to its 30-day safety results. Elective CAS was initiated in the mid 1990s, using an endovascular approach avoiding all surgical wound-related complications of CEA, and the need for general anaesthesia. Therefore, CAS has the potential for becoming the preferred revascularization method, especially in patients who would be considered at significantly high risk for CEA. However, while the prospective, multicentre Carotid and Vertebral Transluminal Angioplasty Study (CAVATAS) conducted between the years 1992 and 1997 reported a similar major risk and effectiveness for CAS and CEA for symptomatic patients with carotid artery disease (13), other registries failed to show a substantial benefit in patients who underwent CAS (14). In those trials, stents were used in only one-third of the patients, and obviously, the stents as well as the techniques of the procedure have since then been refined. Despite