Abstract 18158: Neointimal Coverage of Overlapping Everolimus-eluting Bioresorbable Scaffolds: An Optical Coherence Tomography Study in Native Coronary Arteries

Background: Everolimus-eluting bioresorbable scaffolds (BRS) have thick struts, which could influence shear stress and neointimal formation. According to a previous report, the implantation of overlapping BRS has been associated with delayed coverage at 28-days after BRS implantaion. The aim of the present study was to investigate the relationship between BRS overlap and neointimal formation at long-term, using optical coherence tomography (OCT). Method: 32 patients (35 lesions) treated with overlapping BRS underwent follow-up OCT at 11.8±3.0 months after percutaneous coronary intervention. Neointimal area and %uncovered strut were analyzed by OCT at the overlapping BRS site (OBS), non-overlapping proximal and distal BRS sites (NOPBS and NODBS, respectively). Neointimal area was defined as scaffold area - [lumen area + black box (strut)]. %neointimal area was defined as the neointimal areaх100/ scaffold area. In addition, we evaluated the frequency of inter-strut invaginations (hollows) at OBS and non-overlapping sites, which have been suggested as a marker of abnormal vascular reactions to the eluted drug and/or the polymer. Hollows were counted if they exsisted in-between and outside apposed BRS struts. Result: Mean stent diameter and length of overlapped distal BRS and proximal BRS were 2.96±0.39 and 23.1±6.4mm, and 3.11±0.39 and 19.5±6.4mm, respectively. Mean overlap length of BRS was 2.5±1.3mm. At follow-up, %neointimal area was significantly higher at OBS compared to NODBS and NOPBS (35.1±7.8 vs. 20.1±6.2 vs. 21.3±7.6%, respectively, p=0.01). No correlation was observed between the overlap length and %neointimal area. Additionally, %uncovered strut of NODBS and NOPBS was similar to that of OBS. However, the frequency of hollows in OBS was significantly higher than in both NODBS and NOPBS (0.54±0.52 vs. 0.14±0.18 vs. 0.15±0.28/cross-section, respectively, p=0.02). Conclusion: The site of BRS overlap is associated with increased neointimal proliferation one year after implantation, which could be particularly important in patients with small vessels or diffuse coronary disease. Signs of abnormal vascular reactions might be more frequently observed at the site of overlapping BRS compared to non-overlapping site.