Abstract 18670: Histological Analysis of Neointimal Characteristics in Drug-eluting and Bare Metal Stents Implanted in Human Coronary Arteries: Autopsy Study
Background: The histological characteristics of neointima in DES and BMS has not been fully investigated.
Methods and Results:From our autopsy registry, 15 coronary segments with DES showing restenosis (>75% cross-sectional narrowing within the stent) and 15 restenotic BMS lesions with matched implant duration were selected. The coronary segments were processed at 3-4 mm intervals and assessed histologically at the section with the severest narrowing. The implant duration were similar in DES (361 days) and BMS (330 days). Atherosclerotic change within stent (neoatherosclerosis) was seen in 5 of DES lesions (33%) and 1 of BMS lesions (7%). Cells in neointima around lumen mainly consisted of SMC where DES showed lower cellularity than BMS (904 vs. 1409 cells/mm2, p=0.014). However, α-SMA positive area were equivalent in both stent groups (DES 9.5 %, BMS 10.5 %, p=0.66), suggesting the phenotype difference of SMC with varying levels of actin expression. Percent area occupied by collagen was lower in DES (22.8%) than in BMS (33.2%) (p=0.14) with the latter showing more mature feature (Collagen score: DES 1.0 vs. BMS 1.4, p=0.022). On the contrary, % area of proteoglycan-rich ECM was predominate in DES (69.3%) as compared to BMS (48.0%) (p=0.032). Macrophage and T-lymphocyte infiltration was observed in both stent groups and frequently accompanied by microcapillaries. The number of macrophages identified in BMS (224 /mm2) was slightly higher than in DES (316 /mm2) (p=0.15). T-lymphocyte counts were significantly higher in BMS (312 /mm2) than in BMS (545 /mm2) (p=0.047). The temporal changes of parameters above are summarized in the figure.
Conclusion: The histopathological difference of neointimal characteristics in DES and BMS might be associated with the incidence of late events attributed to neoatherosclerosis or thrombosis. Targeting for modification of SMC phenotype or ECM after stenting will be of use for newer DES to improve long-term clinical outcome.
- © 2012 by American Heart Association, Inc.