Abstract 3441: Differential endothelialization of stent struts across side branches: A Scanning Electron Microscopy analysis.
Background: The higher incidence of MACE events in paclitaxel eluting stents (PES) has been attributed to the presence of coronary artery side branches (SB) within stented segments. This study aimed to evaluate PES struts overlying SB in a porcine model of coronary restenosis.
Methods: In a balloon overstretch model of coronary restenosis (balloon:artery ratio =1.2:1), 20 animals were randomized to either PES or bare metal stents (BMS). After 30 days, 22 stented segments were analyzed by Low Vacuum Scanning Electron Microscopy (SEM) and endothelialization was assessed using a score (0=100% endothelialization; 1=99 – 67%; 2=66 –34%; 3=33–1%; 4=0%). Comparison of the distribution of endothelialization scores for struts overlying and non-overlying SB was performed within each group by the Fisher exact test.
Results: A total of 18 struts overlying SB (10 PES and 8 BMS) sized from 200 to 1800μ m, were identified by SEM. In the BMS group, complete endothelialization was observed in 62.5% of SB struts and 100% of non-overlying SB struts. In PES only 20% of SB struts, but almost 100% of the non-overlying SB struts were completely endothelialized. The endothelialization of struts overlying SB was significantly different in PES and BMS groups(Fig 1A⇓ and Fig 1B⇓), with a higher frequency of impaired endothelialization (scores 3 and 4) in PES struts crossing SB.
Conclusions: PES struts overlying SB showed significantly impaired endothelialization compared with BMS in a pig model of coronary restenosis. This results might offer a new insight to explain the higher incidence of adverse events in PES stented segments. Further studies are needed to confirm the present study results.