Overlapping coronary stents result in an increased neointimal hyperplasia: Insight from a porcine coronary stent model

Clinical experience suggests that overlapping coronary stents result in an increased in-stent restenosis, This study investigates the underlying mechanisms in a porcine coronary model. Single or two overlapping self-made stainless steel single wire sinusoidal helical coil stents were randomly deployed in the right coronary artery of 20 cross-bred pigs. The pigs underwent a control angiogram at 6 weeks and were then sacrificed. Quantitative coronary analysis before, immediately after stent implantation, and at 6 weeks was performed using the semiautomated Polytron 1000 system. Morphometry was performed using a computerized morphometric program. Angiographic analysis revealed a decreased recoil in the overlapping group (1% vs 4%: P < 0.02) and a significantly larger minimal stent lumen diameter at follow-up in the single stent group (2.87 +/- 0.16 vs 2.58 +/- 0.22 mm, P = 0.005). Histopathology showed a significantly increased injury (1.27 +/- 0.43 vs 0.83 +/- 0.44, P = 0.042) and inflammatory reaction (1.51 +/- 0.11 vs 1.09 +/- 0.54, P = 0.035) surrounding the stent filaments in the overlapping stent group. Morphometric analysis showed a significantly higher neointimal hyperplasia (3.34 +/- 0.68 vs 2.16 +/- 1.48 mm(2), P = 0.034) in the overlapping stent group. Overlapping stents result in a more pronounced coronary vessel injury resulting in more inflammation and neointimal hyperplasia compared to single stents.