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Siena score, a risk modelling study for carotid artery stenting

In recent years an increasing number of papers have dealt with stroke predictors in relation to anatomy, operator experience, lesion characteristics or patient status. To the best of our knowledge, the “Siena Carotid Artery Stenting Score: a risk modelling study for individual patients” (Setacci C et al. Stroke. 2010;41:1259-65.) is the first paper to deal collectively with all of the possible risk factors which can cause stroke following a carotid artery stenting procedure.

 

 

The concept of the study was in early 2000 when a programme of carotid artery stenting was started in the Vascular and Endovascular Surgery Unit, University of Siena, Italy. This study attempted to generate an objective scoring system to grade the risk of a neurological adverse event in the 30 days following carotid artery stenting.The scoring procedure was based on patient-related, lesion-related, procedure-related and operator-related variables and their association with the occurrence of stroke at 30 days post-stenting. To identify the carotid artery stenting patients most at risk, we assigned a simple numeral score (0; +0.5; +1; etc.) to all patients on the basis of statistical analysis of each of the abovementioned variables. When the total score for all of the variables was calculated, the carotid artery stenting procedure could be predicted as being at low risk for (minor, major or fatal) stroke (CAS I, stroke rate <1%); at moderate risk (CAS II, stroke rate 1–3%) or at high risk (CAS III; stroke rate >3%).All patients included underwent independent neurological evaluation before and after the procedure and at 30 days. More than 2,000 successful carotid artery stenting procedures were performed. The minor, major, and fatal stroke rates at 30 days were, respectively 1.55%, 1.18%, and 0.61%. 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 >15mm, the need for predilatation, type III arch, bovine arch, arch calcification, procedure time>30 minutes, and the operator’s experience of >50 carotid artery stenting procedures. The operator’s experience of >100 carotid stenting procedures was the only protective factor against the development of stroke at 30 days (odds ratio, 0.81; confidence interval, 0.67– 0.95) (table 1). How has the Siena Carotid Artery Stenting Score changed the routine practice of stenting in the department? Currently, the youngest vascular surgeons with limited experience of carotid artery stenting start with procedures considered as having lower risk for stroke (CAS I) under the guidance of an experienced vascular surgeon. This means that they begin with patients with few comorbidities (no diabetes or cardiac disease), easy common carotid engagement (arch type I), recurrent stenosis, and short lesions (<15mm) that are not calcified, ulcerated, ostial, or symptomatic. If the procedure is prolonged, then the senior vascular surgeon continues it. Complex cases are selected pre-operatively and are only assigned to experienced operators. Although the Siena Carotid Artery Stenting Risk Score seems to be a useful tool to help predict stroke after stenting, it needs to be validated in independent cohorts at a variety of centres before it can be recommended for application, preferably in a randomised comparison with carotid endarterectomy. Maybe this paper could be a starting point for a further multicentre, randomised controlled trial which could really be helpful for a much-discussed procedure, carotid artery stenting.

 

BlankArticle written by professor Carlo Setacci, Vascular and Endovascular Surgery Unit, University of Siena, Siena, Italy.