Mechanisms and predictors of carotid artery stent restenosis: a serial intravascular ultrasound study.

OBJECTIVES The aim of this study was to determine the mechanisms and predictors of carotid artery restenosis after carotid artery stenting (CAS) using serial intravascular ultrasound (IVUS) imaging. BACKGROUND Carotid artery stenting is increasingly used to treat high-grade obstructive carotid disease, but our knowledge of carotid in-stent restenosis and remodeling remains limited. METHODS Post-procedural and 6-month (median 6 months) follow-up quantitative carotid angiography and IVUS were performed after self-expanding stent deployment in 50 internal carotid arteries (ICA). The IVUS measurements at multiple designated sites included minimal luminal diameter, lumen area, stent area (SA), and neointimal hyperplasia area (NIH). RESULTS Late stent enlargement at follow-up was found at all segments, and the percentage increase was greatest at the ICA lesion site (mean +/- SD, 48.9 +/- 35.3%). The NIH, expressed as a percentage of SA, was seen within all segments of the stent and was greatest at the ICA lesion site (37.3 +/- 23.3%). There was a strong positive correlation between the amount of NIH and late stent enlargement (r = 0.64; p < 0.001). Immediate post-procedural minimum ICA SA (r = -0.37; p < 0.01) and stent expansion (r = -0.44; p = 0.001) correlated negatively with the percentage restenotic area at follow-up. CONCLUSIONS Although self-expanding carotid stents generate considerable neointimal hyperplasia, the process is balanced by marked late stent enlargement. Small stent dimensions immediately post-procedure were associated with a higher risk of restenosis.