Background and purpose: Several large multicenter trials have demonstrated that carotid endarterectomy (CEA) benefits patients with symptomatic moderate-to-high-grade carotid stenosis (CS), but not those with low-grade CS. Accumulating evidence from vascular biology studies indicates that plaque stability in addition to stenosis rate considerably impacts risk for ischemic events. The present study aimed to determine the characteristics of symptomatic low-grade CS that was refractory to medical treatment and confirm the safety and efficacy of CEA.
Methods: We studied 61 (male, n = 54; mean age, 71.0 ± 6.5 years) consecutive patients with symptomatic CS who underwent CEA. The patients’ characteristics, preoperative carotid MRI plaque imaging findings, and short- and long-term outcomes after CEA were compared between those with low-grade CS (< 50%, n = 17) and those with moderate-to-high grade CS (≥ 50%, n = 44). Plaque excised from patients with low-grade CS was also histologically assessed. We considered CEA to treat low-grade CS when recurrence was refractory to aggressive medical approaches.
Results: The characteristics did not significantly differ between patients with low-grade and moderate-to-high-grade CS. The degree to which MRI detected intraplaque hemorrhage was significantly higher (P = 0.04) and the extent of expansive arterial remodeling tended to be higher (P = 0.18) in patients with low-grade CS. Intraplaque hemorrhage was confirmed in all 17 excised plaques from patients with low-grade CS and in 15 ruptured fibrous caps and two erosions. Short-term outcomes, including the rate of internal shunt deployment under selective use based on intraoperative monitoring and new ischemic lesions after CEA on postoperative diffusion weighted images, as well as long term outcomes did not significantly differ between the groups.
Conclusions: CEA was safe and effective for symptomatic low-grade CS that was refractory to aggressive medical treatment. Plaque characterization by MRI has the potential to provide more accurate stroke risk stratification for the management of low-grade CS.