Ultrasound Hemodynamic Predictors of Progression in Moderate Asymptomatic Carotid Artery Stenosis

BACKGROUND: Risk factors associated with progression of carotid artery stenosis remain poorly defined. The aim of this study was to identify duplex ultrasound hemodynamic parameters associated with progression from moderate to severe asymptomatic carotid artery stenosis. METHODS: We conducted a retrospective cohort study of consecutive patients with peripheral artery disease (PAD) and moderate asymptomatic internal carotid artery (ICA) stenosis (50%-69%), defined by an ICA peak systolic velocity (ICA-PSV) of 125-230 cm/s or an internal to common carotid artery PSV ratio (ICA/CCA ratio) of 2.0-4.0. Baseline demographic, clinical, and duplex ultrasound data were collected. The primary outcome was progression to severe carotid stenosis (70%-99%) or complete carotid occlusion during follow-up. Associations between hemodynamic variables and disease progression were assessed using Cox proportional hazards regression models. RESULTS: A total of 331 patients were included (median age 71 years, 79.5% male). During a mean follow-up of 4.4 years, 52 patients (15.7%) progressed to severe stenosis or occlusion. Progression-free survival rate at 5 years was 84%, respectively. In univariate analysis, ICA-PSV, ICA end-diastolic velocity, ICA-CCA ratio, and (marginally) a history of tobacco consumption were associated with stenosis progression. After adjustment for age, sex, and smoking status, both ICA-PSV and ICA/CCA ratio remained independently associated with progression (hazard ratio [HR] = 1.023, P value <0.001 and HR = 2.470, P-value <0.001, respectively). The combination of ICA-PSV and ICA/CCA ratio demonstrated good discriminative performance (C-statistic = 0.75). Optimal thresholds related to progression were ICA-PSV >180 cm/s and ICA/CCA ratio >2. Five-year progression rates were 3.7% among patients with ICA-PSV 125-180 cm/s and ICA/CCA ratio ≤2.0 (n = 120), 18.0% among those with either ICA-PSV >180 cm/s or ICA/CCA ratio >2.0 (n = 154), and 43.5% among those with both ICA-PSV >180 cm/s and ICA/CCA ratio >2.0 (n = 57). CONCLUSION: Among patients with PAD, moderate asymptomatic carotid stenosis characterized by ICA-PSV >180 cm/s and/or an ICA/CCA ratio >2.0 is associated with increased risk of progression. Patients meeting both hemodynamic criteria appear to be at particularly high risk and may warrant more frequent follow-up.