Siena carotid artery stenting score: a risk modelling study for individual patients

BACKGROUND AND PURPOSE: Carotid artery stenting (CAS) still entails a considerable peri-interventional risk of serious neurological adverse events. The aim of this study was to generate a score to grade this risk for CAS in individual patients. METHODS: This is a 9-year prospective study. Consecutive patients with > or =70% carotid artery stenosis were treated with a standardized CAS procedure. All patients included underwent independent neurological evaluation before and after the procedure and at 30 days. The rates of transient ischemic attack and minor, major, and fatal stroke were recorded. Stroke predictors were analyzed and a score system was generated using Arabic numerals for all variables to preoperatively grade the individual patient risk of stroke. RESULTS: Two thousand one-hundred twenty-four successful CAS procedures were performed. The transient ischemic attack and minor, major, and fatal stroke rates at 30 days were, respectively, 2.72% (n=60), 1.55% (n=33), 1.18% (n=25), and 0.61% (n=13). Multiple regression analysis showed that the following significantly predicted the 30-day risk of treatment-related stroke: cardiac disease, symptomatic patient, diabetes, calcification or ulceration at the level of the lesion, native and ostial lesion, lesion length >15 mm, the need for predilatation, type III arch, bovine arch, arch calcification, procedure time >30 minutes, and the operator's experience of <50 CAS procedures. The operator's experience of >100 CAS procedures was the only protective factor against the development of stroke at 30 days (odds ratio, 0.81; confidence interval, 0.67-0.95). The Siena CAS score was developed from these variables and predicted the risk of CAS within the 3 categories of low risk (<1%; CAS I), medium risk (1% to 3%; CAS II), and high risk (>3%; CAS III), with a sensitivity of 0.82 and specificity of 0.79. CONCLUSIONS: The Siena CAS risk score seems to be a useful tool to help predict stroke after CAS but needs to be validated in independent cohorts at a variety of centers before it can be recommended for application, preferably in a randomized comparison with carotid endarterectomy.