Neointimal coverage on acute vessel wall injuries after stenting: 6-month follow-up study

BACKGROUND: Stent implantation often creates local vessel wall injuries which can be characterized in detail by optical coherence tomography (OCT). Little is known about the neointimal coverage at these areas. We aimed to evaluate neointimal coverage of vessel wall injuries area associated with stent implantation. METHODS: We retrospectively selected patients implanted with sirolimus-eluting stents (SES) having excellent OCT images immediately after stent implantation and at the 6-month follow-up. All OCT cross-sectional images were divided into three groups: intra-stent tissue prolapse (ISTP) areas, intra-stent dissection flaps (ISDF) areas, and non-injuried areas. The neointimal coverage in included sections was evaluated at 6 months follow-up. RESULTS: Finally, 1690 cross-sectional images in 74 stents were analyzed totally. Among which, 240 images (14.20%) involved ISTP areas, 124 images (7.34%) at ISDF areas, and 1326 images (78.46%) at non-injuried areas. All ISTP and ISDF were disappeared at six months follow-up, Neointimal thickness at ISTP and ISDF areas increased significantly compared to the one in non-injuried areas (97.4 +/- 40.3 mu m vs. 68.4 +/- 47.6 mu m, P< 0.001; 92.7 +/- 49.8 mu m vs. 68.4 +/- 47.6 mu m, P< 0.001). Mean neointimal area of ISTP and ISDF areas was almost the same (0.8 +/- 0.3 mm(2)), which both had a significant difference compared to mean neointimal area (0.6 +/- 0.4 mm(2)) at non-injuried areas (p1<0.001, p2= 0.006). CONCLUSIONS: Intra-stent tissue prolapse and intra-stent dissection flaps have benign clinical course up to 6 months. The areas with these local complications, however, have greater neointimal hyperplasia compared to the non-injuried areas.