Cerebral microembolization after protected carotid artery stenting in surgical high-risk patients: results of a 2-year prospective study.

BACKGROUND: This was a prospective single-center study to assess and analyze cerebral embolization resulting from carotid artery stenting with neuroprotective filter devices in patients considered as poor surgical candidates for surgical carotid endarterectomy. METHODS: Fifty-three consecutive patients with an internal carotid artery stenosis were treated by placement of carotid Wallstents with two different types of temporary distal filter protection devices: the Spider filter and the FilterWire. Diffusion-weighted magnetic resonance imaging (DWI) of the brain was obtained 24 hours before the procedure and within 5 to 30 hours after the procedure to detect ischemic brain lesions resulting from the procedure. Inclusion criteria were symptomatic (> or =70%) or asymptomatic (> or =80%) stenoses in surgical high-risk patients. RESULTS: Two (4%) regressive minor strokes occurred. Postprocedural DWI detected new focal ischemic lesions in 21 patients (40%). The average number of lesions was 5.9 per patient, and the mean lesion volume was 1 mL or less in 19 patients (90%). Small differences were found in the lesion distribution: homolateral anterior circulation in eight cases (15.1%), other vascular territories in seven cases (13.2%), and homolateral anterior circulation plus other vascular territories in six cases (11.3%). The microembolization risk seemed nonpredictable on the basis of clinical parameters and internal carotid artery lesion characteristics. An increased risk in the rate of ipsilateral hemispheric embolization has been observed in difficult carotid arch implantations (P = .04). CONCLUSIONS: The incidence of new focal ischemic lesions detected by DWI is higher than expected on the basis of previous reports. Embolization from the aortic arch or common carotid arteries could account for most of those events in patients considered as surgical high-risk patients. Although 90% of the events were clinically silent, this high rate of microembolization raises questions about the possible consequences on cerebral cognitive functions.