Basalus M.W.Z. - Scanning Electron Microscopic Assessment of Coating Irregularities and Their Precursors in Unexpanded Durable Polymer-Based Drug-Eluting Stents

Mounir W.Z. Basalus, Kenneth Tandjung, Thea van Westen, Hanim Sen, Pasquelle K.N. van der Jagt, Dirk W. Grijpma, Aart A. van Apeldoorn, and Clemens von Birgelen

Catheterization and Cardiovascular Interventions 2012

Abstract

Objectives: To assess and quantify coating irregularities on unexpanded and expanded
durable polymer-based drug-eluting stents (DES) to gain insights into the origin of coating
irregularities. Background: Previous scanning electron microscopy (SEM) studies in
various expanded DES revealed differences in frequency and size of coating irregularities
between DES types and specific distribution patterns, however, the origin of these
irregularities is unclear. Methods: We assessed at bench side a total of 1,200 SEM
images obtained in 30 DES samples (15 expanded and 15 unexpanded) of Cypher Select
Plus, Taxus Liberte´ , Endeavor, Xience V, and resolute. Results: For most coating irregularities
seen on expanded DES (72%; 23/32), a matching irregularity (n 5 18/23) and/or
its precursor (n 5 11/23) was observed in unexpanded DES. Unexpanded Cypher select
showed (small) crater lesions and cracks together with precursors of ‘‘peeling.’’ On
unexpanded Taxus Liberte´ , thinning of polymer, small bare metal areas, wrinkles, and
one precursor type were found.