Supplementary Material for: Asymptomatic Carotid Stenosis: Risk of Progression and Development of Symptoms

<b><i>Background:</i></b> The aim of this study is to evaluate the rate of progression of stenosis and development of symptoms in patients with asymptomatic carotid artery stenosis (aCAS) treated with contemporary medical therapy over a prolonged time interval. <b><i>Methods:</i></b> This study is a retrospective review of consecutive patients diagnosed with moderate or severe aCAS at our institution between 2000 and 2001. Data were gathered from both carotid arteries for each patient excluding vessels operated within 1 year of diagnosis and occlusions. Multivariate analysis was performed to analyze factors associated with ipsilateral transient ischemic attack (TIA)/stroke. <b><i>Results:</i></b> We identified 214 patients (58.8% men; median age 70 years) and collected data on 349 vessels. Degree of stenosis was severe (>70%) upon diagnosis in 92 (26.4%) vessels. Median length of follow-up was 13 years (interquartile range 10-14), and mean number of time points for follow-up imaging were 8.1 ± 3.9. Progression of stenosis was observed in 237 (67.9%) vessels, and 72 (20.6%) patients developed symptoms ipsilateral to the stenosis (TIA in 14.4%, non-disabling stroke in 4%, disabling stroke in 2.2%). Median time to appearance of first symptom was 6 years (range 1-13). On multivariate analysis, degree of baseline stenosis, intracranial stenosis >50%, plaque ulceration, silent infarction and previous history of TIA/stroke were associated with ipsilateral TIA/stroke, but progression of stenosis was not. <b><i>Conclusions:</i></b> There was a substantial rate of progression of stenosis in patients with aCAS over time despite adequate medical therapy, but progression of stenosis did not increase the risk of ipsilateral TIA/stroke. Over long-term follow-up, 1 in 5 patients with aCAS developed ipsilateral TIA/stroke, though most events were either transient or non-disabling.