Re-endothelization and Inflammatory Reaction at Site of Overlapping Drug-Eluting Stents in a Porcine Coronary In-Stent Restenosis Model

ABSTRACT

BACKGROUND AND OBJECTIVES: This study was conducted to evaluate the inflammatory reaction at sites of overlapping stents in a porcine in-stent restenosis (ISR) model. MATERIALS AND METHODS: Twenty bare metal stents (BMS, Group I; n=10), 20 sirolimus-eluting stents (SES, Group II; n=10), 20 paclitaxel-eluting stents (PES, Group III; n=10), 10 PESs and 10 SESs (Group IV; n=10) were deployed and overlapped in the left anterior descending coronary arteries of 40 pigs. Follow-up coronary angiograms and histopathologic analysis were performed at 4 weeks after stenting. RESULTS: The minimal luminal diameter of the overlapped segment at 4 weeks was smaller in group I than that in the other groups (1.78+/-0.13 mm vs. 2.79+/-0.09 mm vs. 2.90+/-0.04 mm vs. 2.80+/-0.07 mm, respectively, p<0.001). The neointimal area (5.51+/-0.58 mm2 vs. 2.38+/-0.53 mm2 vs. 2.07+/-0.37 mm2 vs. 2.39+/-0.58 mm2, respectively, p<0.001) and the area stenosis (68.74+/-4.02% vs. 27.79+/-4.73% vs. 23.66+/-3.24% vs. 27.63+/-4.07%, respectively, p<0.001) of the overlapped segment were significantly higher in Group I than that in the other groups. The inflammatory score of the overlapped segment was significantly higher in Group III than that in the other groups (1.80+/-0.42 vs. 2.10+/-0.32 vs. 2.90+/-0.31 vs. 2.50+/-0.52, respectively, p<0.001). The endothelization score of the overlapped segment was significantly lower in Group III than that in the other groups (2.80+/-0.42 vs. 2.30+/-0.67 vs. 1.30+/-0.48 vs. 2.10+/-0.74, respectively, p<0.001). CONCLUSION: Compared with the BMS, the DES inhibits neointimal hyperplasia, but inflammation and poor endothelization are observed at the sites of overlapped stents.