Longitudinal deformation of contemporary coronary stents: an integrated analysis of clinical experience and observations from the bench.

OBJECTIVE: To report clinical experience with longitudinal stent deformation (LSD) and observations from the bench.
BACKGROUND: LSD was recently reported with thin-strut coronary stents. Whether it is related to a particular stent or constitutes a class-effect remains debatable.
METHODS: After 2 cases of LSD were reported, information was sent to operators to warn of this event and identify possible cases. All cases were reviewed to ensure LSD had occurred. Simultaneously, bench testing was conducted to identify the susceptibility of stents to longitudinal compression and whether LSD detection is influenced by fluoroscopic stent visibility.
RESULTS: Between July 2010 and November 2011, 2,705 coronary interventions were performed with 4,588 stents (Promus Element = 41.6%, Xience Prime = 24.4%). Six patients with LSD were identified, all with Promus Element (0.31%). Wire bias was a predisposing factor in 4 cases. All patients were treated with postdilatation and/or additional stenting. No adverse events occurred (mean 5.8 months). In bench testing, LSD occured in all examined stents, but at different levels of applied force (weight). Most shortening at 50 g was observed with Promus Element (38.9%), as was the best visibility of LSD on x-ray images. With postdilatation all stents showed some re-elongation.
CONCLUSION: In our practice LSD was a rare observation only seen with the Promus Element stent. When subjected to longitudinal compression in a bench test all contemporary stents can be compressed. Compression of Promus Element occurs at a lower force, but it is the only stent where deformations are detected with x ray. Postdilatation can partially improve LSD. ©2012, Wiley Periodicals, Inc.