A lipid-poor plaque and asymptomatic status in women are associated with higher peak systolic velocity on duplex ultrasound after carotid endarterectomy.

Objectives: Recurrent stenosis is a drawback of carotid endarterectomy (CEA), and may lead to recurrent symptoms and reintervention. Restenosis can be detected by duplex ultrasound scanning (DUS) with cutoff values based on peak systolic velocity (PSV), which vary among vascular laboratories. On short term, histological carotid plaque characteristics have shown to predict DUS-based restenosis rates. Therefore, we aimed to analyze the association of both plaque and patient characteristics with continuous PSV values in the carotid artery at different timepoints during follow-up after CEA.

Methods: 760 atherosclerotic plaques of 725 patients, who underwent CEA between 2003 and 2011, were analyzed for smooth muscle cells, collagen, macrophages, lipid core, plaque hemorrhage, and vessel density. Patients underwent DUS at 3 and 12 months follow-up and yearly thereafter. The association between plaque and patient characteristics and mean PSV was analyzed in a multivariable analysis, at 3 months and total (mid-term) follow-up.

Results: Patients with a large lipid core in their plaque (n = 170) had significantly lower PSVs at 3 months follow-up; 109 cm/s, 95% confidence interval (CI): 103-116 versus 118 cm/s, 95% CI: 114-122, (P = 0.03) for no or small lipid core (n = 454). After mid-term follow-up (median duration of 2.5 years, interquartile range 1.7-4.3), these PSV values were not significantly different (115 vs. 111 cm/s, P = 0.278). Presence of contralateral stenosis, female sex, and asymptomatic presentation in women were independently associated with higher PSVs at mid-term follow-up.

Conclusions: Dissection of a lipid-poor plaque showed an independent association with higher PSVs in the internal carotid artery 3 months after CEA, not after mid-term follow-up. In women, significantly higher PSVs were found after midterm follow-up, especially if they were asymptomatic.