Carotid artery re-stenosis: multi-variable analysis

Background
Carotid artery stenosis (CAS) is the narrowing of the lumen of the carotid artery. It is a major cause of stroke. Stroke accounts for 1 in every 18 deaths in the US. Carotid artery stenting is an FDA approved method for the treatment of CAS. However, carotid artery stenting has been fraught with lumen loss and in-stent restenosis. The literature is limited in regard to variables affecting long term patency after carotid artery stenting.

Methods
In this study, we evaluate the relationship between certain patient characteristics and risk of restenosis. To test this relationship, charts of 148 patients who were treated by a single operator for CAS with stent placement were retrospectively reviewed and a multiple regression analysis was performed. The variable used for determining the presence or absence of restenosis is a finding of greater than 50% in-stent restenosis as defined by carotid duplex ultrasound at a certain time.

Results
Findings showed: 123 patients did not develop signs of restenosis after 1 year, while 25 patients developed restenosis defined on annual follow up carotid duplex ultrasound. The odds ratio of developing restenosis for current/former smokers vs. never smokers was 10.085 (p-value= 0.018). The odds ratio of developing restenosis for patients with closed vs. open cell design stents was 12.455 (p-value= 0.008). The odds ratio of developing restenosis for a patient with a hybrid stent vs. open stent was 8.041 (p-value= 0.058). For every 1 mm increase in stent diameter, we see about a 50.1% decrease in the odds of having re-stenosis (p-value= 0.021). After expanding the scope of time evaluated from the 1 year mark to a 3 year mark, we find that 4 more patients had developed restenosis and that stent length becomes a significant variable. For every 1 mm increase in stent length, we see about 11.2% increase in odds of re-stenosis (p-value=0.039).

Conclusions
Data suggests that the risk of developing carotid artery restenosis is elevated in those with a history of previous or current tobacco use and in those treated with closed-cell design or hybrid stents as opposed to open-cell design stent. Restenosis is also positively correlated with the length of the stent placed, and inversely correlated with stent diameter.