Re-endothelization and inflammatory reaction at site of overlapping drug-eluting stents in a porcine coronary in-stent restenosis model

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.