Relation Between the Length of the Internal Carotid Stenotic Segment and Ischemic Cerebrovascular Events as Well as White Matter Lesion Load

Background and Purpose: Internal carotid artery stenosis ≥70% is a leading cause of ischemic cerebrovascular events. However, a considerable percentage of stroke survivors with symptomatic internal carotid artery stenosis have <70% stenosis with a vulnerable plaque. Whether the length of internal carotid artery stenosis is associated with high risk of ischemic cerebrovascular events or with white matter lesions is poorly investigated. Our main aim was to investigate the relation between the length of internal carotid artery stenosis and the development of ischemic cerebrovascular events as well as ipsi-, contralateral as well as mean white matter lesion load. Methods: In a retrospective cross-sectional study, 168 patients with 208 internal carotid artery stenosis were identified. The degree and length of internal carotid artery stenosis as well as plaque morphology (hypoechoic, mixed or echogenic) were assessed on ultrasound scans. The white matter lesions were assessed in 4 areas separately, (periventricular and deep white matter lesions on each hemisphere), using the Fazekas scale. The mean white matter lesions load was calculated as the mean of these four values. Results: A statistically significant inverse correlation between the ultrasound-measured length and degree of internal carotid artery stenosis was detected for symptomatic internal carotid artery stenosis ≥70% (Spearman correlation coefficient ρ = –0.57, p < 0.001, n = 51) but neither for symptomatic internal carotid artery stenosis <70% (ρ = 0.15, p = 0.45, n = 27) nor for asymptomatic internal carotid artery stenosis (ρ = 0.07, p = 0.64, n = 54). The median (IQR) length for symptomatic internal carotid artery stenosis <70% and ≥70% was 17 (15–20) and 15 (12–19) mm (p = 0.06), respectively, while that for symptomatic internal carotid artery stenosis <90% and symptomatic internal carotid artery stenosis 90% was 18 (15–21) and 13 (10–16) mm, respectively (p < 0.001). Among patients with internal carotid artery stenosis <70%, a cut-off length of ≥16 mm was found for symptomatic internal carotid artery stenosis rather than asymptomatic internal carotid artery stenosis with a sensitivity and specificity of 74.1% and 51.1%, respectively. Irrespective of the stenotic degree, plaques of the symptomatic internal carotid artery stenosis compared to asymptomatic internal carotid artery stenosis were significantly more often echolucent (43.2 vs. 24.6%, p = 0.02). The length but not the degree of internal carotid artery stenosis showed a very slight trend toward association with ipsilateral white matter lesions and with mean white matter lesions load. Conclusion: We found a statistically insignificant tendency for the ultrasound-measured length of symptomatic internal carotid artery stenosis <70% to be longer than that of symptomatic internal carotid artery stenosis ≥70%. Moreover, the ultrasound-measured length of symptomatic internal carotid artery stenosis