Significance Of Carotid Plaque Echomorphology In Embolization Risk During Carotid Artery Angioplasty and Stenting

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Peter H. Lin, MD, Ruth L. Bush, MD, Wei Zhou, MD, Alan B. Lumsden, MD.
Baylor College of Medicine, Houston, TX, USA.

PURPOSE: While carotid artery stenting (CAS) has emerged as a treatment alternative to carotid endarterectomy, stroke due to procedural-related embolization remains a major concern. The purpose of this study was to evaluate the significance of carotid plaque echomorphology by means of normalized gray scale analysis in embolization risk during carotid artery angioplasty and stenting.
METHODS: All patients undergoing CAS with cerebral protection device during a recent 26 month period were analyzed. Preoperative carotid duplex scanning were analyzed using normalized gray-scale median (GSM) based on two anatomic reference points: blood (GSM of 0) and adventitia (GSM of 190). The plaque echodensity was determined by the normalized GSM of the pixels of the carotid plaque. The incidence of CAS-associated embolization as detected by the neuroprotection device was analyzed in relation to plaque echomorphology and relevant clinical variables.
RESULTS: A total of 93 CAS procedures were performed in 85 patients (79 male; overall mean age 68 years) with a mean luminal stenosis of 85%. Thirty three plaques (35%) were transient ischemic attacks, 36 plaques (39%) were associated with stroke, and 24 plaques (26%) were asymptomatic. Sixty eight lesions (73%) were de novo plaques while 25 lesions (27%) were radiation-induced or recurrent stenosis. Neuroprotection-detected embolization occurred in 54 CAS procedures (58%). The mean GSM value was 29 +/- 14 for plaques associated with embolization and 68 +/- 21 for plaques without embolization (p < 0.03). The incidence of embolization was increased with hypoechoic plaque (GSM < 20, Spearman correlation, P =.042, r = -0.23). However, no correlation was found between embolic incidence with the degree of stenosis, preoperative symptoms, or cardiopulmonary morbidities.
CONCLUSIONS: Carotid plaque echodensity as determined by normalized gray-scale median analysis provides important clinical value which correlates with CAS-related embolization. These data support the use of embolization protection device in CAS procedure particularly in patients with hypoechoic plaques.