Background: The clinical benefit of second-generation drug-eluting stents (2nd DES) has been established, compared to first-generation drug-eluting stents (1st DES). However, pathological response after 2nd DES implantation remains unclear, particularly in the Japanese population.
Methods: Using specimens obtained by autopsy, we compared the histology between 2nd DES (41 sections) and 1st DES (38 sections) lesions within 1 year after stent implantation to evaluate early tissue reaction in Japanese patients. Stent segments were fixed with 10% buffered formalin and embedded in plastic, followed by hematoxylin-eosin and Masson's trichrome staining. Ratio of covered stent struts was calculated, and the area of fibrin deposition was morphometrically evaluated. The degree of inflammation around struts was examined semi-quantitatively (score 0-3).
Results: The ratio of covered struts and mean fibrin area of 2nd DES were 0.69±0.05 and 658.0±173.4μm2. Those of 1st DES were 0.44±0.12 and 3107.5±1405.9μm2. In the 2nd DES, there was significantly less fibrin deposition and a higher covered struts ratio. The inflammation score was significantly lower in 2nd DESs compared to 1st DESs (1.02±0.16 vs. 1.19±0.54, p<0.05).
Conclusions: Histopathological analysis showed advanced healing process in 2nd DES compared with 1st DES lesions. These results are consistent with clinical beneficial outcome of 2nd DES implantation.
Keywords: Coronary artery; Drug-eluting stent; Everolimus-eluting stent; Inflammation; Pathology.
Copyright © 2017 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.