Post-procedural Microembolic Events Following Carotid Angioplasty and Stenting and Carotid Endarterectomy

Maureen M. Tedesco, MD, Jason T. Lee, MD, Ronald L. Dalman, MD, Christopher Loh, MD, Barton Lane, MD, Jason Haukoos, MD, Joseph H. Rapp, MD and Sheila M. Coogan, MD
Stanford University Medical Center, Division of Vascular Surgery, Palo Alto, CA,Denver, CO and San Francisco, CA

Objective: The relative safety of percutaneous carotid interventions remains controversial. Few studies have used diffusion-weighted magnetic resonance imaging (DW-MRI) to evaluate the safety of these interventions. We compared the incidence and distribution of cerebral microembolic events after carotid angioplasty/stenting (CAS) with distal protection to standard open carotid endarterectomy (CEA) using DW-MRI.
Methods: Over an 18 month period from November 2004 to April 2006, 67 carotid interventions [25 CAS, and 42 CEA) were performed in 64 males at a single institution. Pre- and post-procedure DW-MRI were performed on all of the CAS patients and the 13 most recent CEA patients. The hospital records of these 38 patients (25 CAS and 13 CEA) were retrospectively reviewed. The incidence and location of acute, post-procedural microemboli were determined via independent, blinded review by two neuroradiologists.
Results: Seventeen (68%) CAS patients demonstrated evidence of postoperative, acute, cerebral microemboli by DW-MRI vs. none of the CEA patients (P<0.0001, Odds Ratio=55, 95% CI, 3-1051). Of the 17 CAS patients with postoperative emboli, 9 (53%) were ipsilateral to the index carotid lesion, 3 (18%) contralateral, and 5 (29%) bilateral. Two patients developed posterior fossa lesions. The mean number of microemboli identified in the CAS group was 3.0 + 5.1 ipsilateral lesions (range 0-21, median 1) and 1.0 + 1.8 contralateral lesions (range 0-5, median 0). Two (8%) CAS patients experienced temporary neurologic sequelae lasting less than 36 hours. These patients suffered 9 (7 ipsilateral and 2 contralateral) and 22 (21 ipsilateral and 1 contralateral) microemboli, respectively. The mean fluoroscopy time recorded for the CAS procedures was 20.25 minutes. The symptomatic patients’ fluoroscopy times were 14 and 15.7 minutes, respectively. Univariate analysis of patient and procedural characteristics and their relation to the number of microemboli is presented in the Table.
Conclusions: Although our early experience suggests that CAS may be performed safely (no permanent neurologic deficits following 25 consecutive procedures), cerebral microembolic events occur in over two-thirds of the procedures despite the uniform use of distal protection Additional studies will be needed to verify procedural risk factors for microembolic events identified by DW-MRI and determine their long term clinical sequelae, if any, in asymptomatic patients. Until such studies are completed, asymptomatic patients without significant surgical risk factors should be preferentially offered CEA.