Neointimal Characteristics after Everolimus-Eluting Stents Implantation for Chronic Total Occlusion: An Optical Coherence Tomographic Study

Objectives: We investigated neointimal characteristics after everolimus-eluting stent (EES) implantation in chronic total occlusion (CTO) using optical coherence tomography (OCT). Background: CTO is one of the major risk factors for restenosis and reocclusion even in drug-eluting stent era, but detailed neointimal characteristics after stent implantation in CTO is unclear. Methods: We divided our patients (35 EESs) into three groups: patients with stenting for non-CTO lesions (non-CTO group), patients with subintimal stenting (CTO subintima group) and with intra true-lumen stenting for CTO lesions (CTO true lumen group). We compared OCT parameters included the percentage of neointimal hyperplasia area obstruction (%NHAO), mean neointimal hyperplasia (NIH) thickness, the proportion of uncovered struts, the proportion of malapposed struts at cross sectional level and at strut level among three groups. Results: NIH and %NHAO were significantly lowest in CTO subintima group (5 EESs) and highest in CTO true-lumen group (4 EESs) (CTO subintima vs. CTO true-lumen vs. non-CTO: 7.4 (4.4-9.8) vs. 11.5 (7.9-19.2) vs. 10.6 (7.3-15.8) and 48 (36-71) vs. 79 (55-159) vs. 74 (48-117), respectively) while the proportions of uncovered struts and malapposed struts were significantly highest in CTO subintima group and significantly lowest in CTO true-lumen group among the three groups (CTO subintima vs. CTO true-lumen vs. non-CTO: 109 (18.7) vs. 47 (4.7) vs. 375 (7.9) and 36 (6.2) vs. 0 (0) vs. 45 (0.95), respectively). Conclusions: We revealed by OCT that stents implanted in subintima in CTO lesions may have more risks related to stent thrombosis such as malapposed struts and uncovered struts, while stents implanted in true lumen in CTO lesions may have thicker neointimal coverage that might have occurred restenosis.