Longitudinal Stent Deformation: Importance of Stent Type and Stent Apposition

Information on stent longitudinal strength is limited to benchtop models using unconstrained stents, consequently having uncertain clinical significance. This study investigated the effects of stent apposition and tube (artery) compliance on stent stability. Multilink Vision, Multilink 8, Promus Element, Driver and Integrity were examined. Stent size was 3/18 mm or closest length. Four scenarios were tested: in three the stents were well deployed and in the final test, stents were purposely severely malapposed. In the well-deployed models, three tubes with different compliance were tested. Stents were compressed by applying a single point force. Malapposed stents compressed extensively at 50 and 100 gm., especially Element, which deformed double the amount of the other stents. At higher forces (150 gm.), the magnitude of difference was reduced. Stent apposition had a profound protective effect and limited differences between stents. Stiffer tubes provided more protection to stent deformation. All stents are vulnerable to deformation when severely malapposed but the Element is significantly more so. Well-apposed stents are considerably more resistant to longitudinal compression such that differences between stents become minimal. More rigid tubes offered greater protection. Clinical implications regarding stent sizing and postdilation strategy are significant.