PP11. Prevalence and Clinical Significance of Stent Fracture and Deformation Following Carotid Artery Stenting

Article Outline

• Objective
• Methods
• Results
• Conclusions
• Copyright

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Objective 

Carotid artery stenting (CAS) is a developing intervention for carotid artery stenosis, and the long-term outcomes remain unclear. The purpose of this study was to determine the prevalence of carotid stent fractures or deformations following CAS and the clinical significance of these stent changes.

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Methods 

This is a retrospective analysis of 276 consecutive CAS performed in 250 patients at a single academic institution between 8/2000 and 10/2008. 100 stents were evaluated with multi-planar plain films of the neck to assess for stent fracture or significant deformation. Deformation was defined as an increase in stent cell area due to stent strut deformation. A subjective assessment was made by 2 independent observers (kappa = 1.0). Rate of stent fracture & deformation was determined using Kaplan-Meier life table analysis and compared using the log rank test. Study endpoints also included recurrent carotid artery stenosis of >70% requiring re-intervention and post-operative stroke.

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Results 

Of the 100 stents evaluated with neck films, there were 50 closed cell stents (Wallstent 11, Xact 37, other 2) and 50 open cell stents (Acculink 22, ViVexx 15, Precise 13). Overall, there were 3 stent fractures and 24 deformed stents. All stent fractures occurred in closed cell Xact stents placed > 1 year prior to examination (3 of 25 or 12%). 0 of 10 Wallstents with follow up > 1 year were fractured. No open cell stents fractured. 2 of the 3 stent fractures were associated with the presence of calcified plaque noted on plain films. Stent deformation was significantly associated with both open cell stent type (HR 15.9, P=.007) and the presence of calcified plaque on plain film (HR 16.3, P=.007). Overall at a median follow up of 22.5 months (IQR 0.9 to 63.5 months), in-stent restenosis requiring treatment occurred in 6% and late stroke in 1%. Neither stent fracture nor deformation was significantly associated with the occurrence of late stroke or re-intervention.

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Conclusions 

Stent fracture and deformation is not uncommon following CAS and is strongly associated with the presence of heavily calcified carotid vessels. Whether a carotid stent fractures or deforms correlates with stent cell design. Larger studies will be necessary to determine the possible clinical significance of carotid stent fracture and deformation.