Neointimal hyperplasia and late pathologic remodeling in a porcine coronary stent model

Background. Although coronary stenting has been demonstrated to significant ly reduce restenosis compared to conventional angioplasty, occurrence of in -stent stenosis still remains one of the major limitations. This study inve stigates the influence of stent strut diameter on injury, inflammatory resp onse, thrombosis and neointimal hyperplasia in a porcine coronary artery. Methods. Coil stents made of either a 0.12 mm, 0.15 mm or 0.18 mm wire were randomly implanted in the right coronary arteries of 30 pigs. Quantitative coronary angiography analysis was performed before, immediately after, and 6 weeks following the stenting procedure. At 6 weeks, histopathology for e valuation of injury, thrombosis and inflammation, as well as morphometry fo r calculation of the neointimal hyperplasia and internal elastic lamina are a were performed. Results. Quantitative coronary analysis showed similar quantitative data be fore and after stent placement in the three groups. At 6 weeks, however, a significantly bigger MLD was found in the 0.18 mm group. Morphometric analy sis at 6 weeks confirmed these results, showing a significantly bigger lume n area in both the 0.18 mm (1.71 +/- 0.66 mm(2)) and 0.15 mm (1.36 +/- 0.53 mm(2)) groups compared to the 0.12 mm group (0.71 +/- 0.38 mm(2)). The cal culated neointimal hyperplasia was similar in the three groups (0.12 mm: 1. 93 +/- 0.51 mm(2); 0.15 mm: 1.68 +/- 0.63 mm(2); and 0.18 mm: 2.16 +/- 1.48 mm(2)). The internal elastic membrane area, however, was significantly big ger in the 0.18 mm (3.87 +/- 1.39 mm(2)) compared to the 0.12 group (2.65 /- 0.53 mm(2)). Conclusion. These results suggest that pathologic remodeling can also play an important role in late lumen loss after stent implantation.