Inflammation and Delayed Endothelization With Overlapping Drug-Eluting Stents in a Porcine Model of In-Stent Restenosis

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