LITERATURE HIGHLIGHTS: Study Seeks to Predict Embolic Potential During CAS

December 14, 2009—Although extracranial carotid stenoses exhibit significant variance in embolic potential, restenotic lesions have a particularly low propensity for embolization. Rajesh K. Malik, MD, et al conducted a study that sought to identify characteristics associated with the increased generation of embolic debris during carotid artery stenting (CAS). The investigators published their findings online ahead of print in the Journal of Vascular Surgery.

According to the investigators, captured particulate was available for analysis in 56 consecutive patients. Demographics include a mean age of 74 years (range, 60&mdas94 years), a mean stenosis of 88% (range, 70%–99%), patients who were symptomatic (27%), previous carotid endarterectomy (CEA) (27%), and previous radiotherapy (7%). Plaque echogenicity, heterogenicity, ulceration, and irregularity were assessed with B-mode duplex ultrasound analysis. Grayscale median (GSM) was calculated from normalized B-mode VHS video recordings. Calcification and degree of stenosis were determined angiographically. Captured particulate debris was evaluated for total number (number > 200 µm, > 500 µm, > 1,000 µm), mean, and median size. Hematoxylin and eosin, trichrome, and von Kossa stains were used for histologic analysis of captured material.

The investigators reported that restenotic carotid stenoses after previous CEA generated minimal embolic debris compared with primary stenoses. Four of 15 patients (27%) with restenotic lesions demonstrated embolic particles; all debris was < 500 µm. All 41 patients with primary stenoses had some embolic debris; particulate size was > 200 µm in 91%, > 500 μm in 72%, and > 1,000 µm in 43%. In primary lesions, the number and size of captured particulate correlated with GSM and with the combined ultrasound findings of echogenicity, heterogenicity, and luminal irregularity/ulceration (95% confidence interval, 4.5–27.6; P < .02). None of these ultrasound factors correlated independently with embolic particulate (P = NS). Patients aged > 70 years exhibited more total particles (8.1 vs 2.3; P = .008) and increased mean particle size (370 vs 157 µm; P = .02). No significant correlation was observed between the number and size of captured embolic particulate and any other variable (stenosis percentage, prior radiotherapy, preprocedural symptoms, periprocedural symptoms, and calcification). Histologically, the embolic debris consisted of extensive amorphous and acellular proteinaceous material. Calcium debris in the embolic particulate was associated with heavily and moderately calcified lesions.