3. Results
In this prospective pilot study, 15 patients with symptomatic (7 patients, 47%) and asymptomatic carotid artery stenosis undergoing CEA were included. Among symptomatic patients, 5 (71%) had recent stroke and 2 (29%) had recent TIA with a median timing of the most recent event of 6 weeks (IQR: 1-18) before the surgery (Table 1). Demographic and clinical characteristics including risk factors, NASCET degree of stenosis, medications and preoperative laboratory results are summarized in Table 1. Symptomatic and asymptomatic patients did not significantly differ in respect to preoperative characteristics. Symptomatic patients had significantly higher hsCRP and D-dimer levels (p =0.016 andp =0.036, respectively). Mean NASCET degree of stenosis was higher in the symptomatic as compared to the asymptomatic group (95% [80-95] and 80% [76.3-83.8], p =0.021, respectively). There was no significant difference in the length of hospitalization and perioperative complications between the two groups, and only one patient in the symptomatic group had an episode of perioperative TIA which has recovered after the surgery.
Carotid plaque features detected on preoperative MRI scan are summarized in Tables 2 and 3. Prevalence of unstable plaque was higher in symptomatic than asymptomatic patients, although this was not statistically significant (63% vs. 37%, p =0.077) (Table 2, Fig. 1). The most common type of carotid plaque as per modified AHA classification was type IV-V (10 patients, 65%) (Table 3).
Differences between preoperative symptoms and histological and immunohistochemistry features of carotid plaques are demonstrated in Table 4. The expression of MMP-9 in CD68 cells within the carotid plaque was found to be significantly higher in symptomatic as compared to asymptomatic patients (86% vs. 25% with the highest expression,p =0.014). In the symptomatic group, 6 out of 7 plaque specimens had the expression of MMP-9 in ≥5 clusters consisted of ≥20 cells or one cluster ≥100 cells, while this was found only in one specimen in the asymptomatic group (Table 4, Fig. 2 and 3). It was also higher in SMA cells in symptomatic patients, but this did not reach statistical difference (p =0.143). In addition, the average MVD by immunohistochemical staining of CD34 was higher among the symptomatic than asymptomatic patients (17 [6-23] vs. 6 [2.5-10], although this did not reach significance (p =0.064). Similarly, lipid core area was larger among the symptomatic than asymptomatic patients, although it did not reach statistical significance (p =0.132).
Differences between MRI features of carotid plaques and histological and immunohistochemistry features of carotid plaques are demonstrated in Table 5. There were no significant differences between several histological features and expression of MMP-9 between the patients with unstable or stable carotid plaque detected by preoperative MRI, although both the average MVD by immunohistochemical staining of CD34 and lipid core area were somewhat higher among patients with unstable than stable plaque. However, this was not significant (p =0.360 andp =0.569, respectively) (Table 5).