BACKGROUND AND PURPOSE: Carotid angioplasty and stenting (CAS) is currently being assessed in the treatment of severe carotid stenosis. However, little data are available concerning patient-related factors affecting the risk of CAS. The purpose of this study was to identify potential clinical risk factors for the development of postprocedural deficits after CAS. METHODS: The clinical characteristics of 299 patients (217 men, 82 women; mean age 69+/-9 years) who underwent CAS for asymptomatic (n=129, 43%) or symptomatic (n=170, 57%) stenoses and the combined 30-day complication rates (any transient ischemic attack [TIA], minor stroke, major stroke, or death) were analyzed with logistic regression analysis. RESULTS: The overall 30-day TIA rate was 3.7%; the minor stroke rate was 5.3%, the major stroke rate was 0.7%, and the death rate was 0.7%. Although patients presenting with a hemispherical TIA or minor stroke had a significantly higher risk than asymptomatic patients (odds ratio [OR] 5.69; 95% confidence interval [CI], 2.03 to 19.57; P<0.001), the complication rates between patients presenting with a retinal TIA and asymptomatic patients was comparable (OR, 1.42; 95% CI, 0.13 to 9.09; P=0.6). Multivariate regression analysis revealed advanced age (OR, 1.06; 95% CI, 1 to 1.11; P<0.05), stroke (OR, 8; 95% CI, 2.6 to 24.4; P<0.01) or hemispherical TIA (OR, 4.7; 95% CI, 1.6 to 13.3) as presenting symptoms as independent clinical predictors of the combined 30-day outcome measures any TIA, stroke, or death. CONCLUSIONS: Aside from advanced age and symptom status, the type of presenting event predicts postprocedural complications after CAS. When evaluating the outcome of CAS and comparing this treatment modality to surgery, patients should be stratified according to their presenting event.