Initial pathological responses of second-generation everolimus-eluting stents implantation in Japanese coronary arteries: Comparison with first-generation sirolimus-eluting stents

Abstract

BackgroundThe 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. MethodsUsing 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). ResultsThe 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). ConclusionsHistopathological 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.