Scanning electron microscopic analysis of polymer damage in drug-eluting stents during multiple stenting.

Polymer damage of drug-eluting stents (DES) during percutaneous coronary intervention procedure could be associated with stent restenosis. We assessed the damage to the drug-containing polymer of DES during multiple stenting in a phantom model by using scanning-electron microscopy (SEM). Unexpanded sirolimus-eluting stent (SES; n = 15) was delivered through the formerly expanded SES (n = 15) in a bended polytetrafluoroethylene plastic tube. The stent was subcategorized into 4 segments (S), including distal (S ₁), mid distal (S ₂), mid proximal (S ₃) and proximal segments (S ₄), for qualitative SEM assessment. Polymer damage, such as detachments, missing or tears, was observed not only in the outer surface of the unexpanded stents (100 %) but also in the inner surface of the formerly expanded stents (100 %). There was a significant difference in the frequency of polymer damage among the 4 segments in the unexpanded stents (S ₁ vs. S ₂ vs. S ₃ vs. S ₄: 86.7 vs. 80.0 vs. 53.3 vs. 40.0 %, p = 0.022) and the formerly expanded stents (S ₁ vs. S ₂ vs. S ₃ vs. S ₄: 80.0 vs. 73.3 vs. 73.3 vs. 40.0 %, p = 0.041). The damage was distributed more frequently in distal part than proximal part of either unexpanded stents (S ₁ vs. S ₄, p = 0.0079) and the formerly expanded stents (S ₁ vs. S ₄, p = 0.0079). Delivery of DES through a formerly expanded DES could cause damage to drug-containing polymer of the stents. [ABSTRACT FROM AUTHOR]