Abstract 2223: Angioscopic Evaluation of Neointima Coverage: Sirolimus Drug-Eluting Stent vs. Bare Metal Stent
Background: Process of neointima formation after bare metal stent (BMS) implantation was previously elucidated by angioscopic observations. However, the process after the implantation of drug-eluting stent (DES) has not been clarified. Therefore, we compared the angioscopic appearance of neointima over DES and BMS at 6 months after implantation.
Methods: A series of patients who received the implantation of BMS (n = 13) or Sirolimus DES (n = 24) were included. Angiographic and angioscopic examination was performed at 6 months. Color of stented lesion (white or yellow), coverage of stent by neointima (not covered, covered by thin layer, or buried under neointima), and thrombus at stented lesion (presence or absence) were angioscopically evaluated. Additionally, 2 DES implanted lesions were observed by angioscopy at 1.5 years.
Results: DES was not covered in 11 (46%) lesions, covered by thin layer in 21 (88%) lesions, and buried under neointima in 11 (46%) lesions, at least in part. BMS was not covered in 1 (8%) lesion, covered by thin layer in 4 (31%) lesions, and buried under neointima in 13 (100%) lesions, at least in part. Thrombus was present at 10 (42%) and 1 (18%) lesion where DES and BMS were implanted, respectively. Prevalence of stent buried under neointima (46% vs. 100%, p = 0.001) was lower and prevalence of thrombus (42% vs. 8%, p = 0.03) higher at DES compared with BMS implanted lesions. Prevalence of thrombus (42% vs. 17%, p = 0.007) was higher at the lesions with yellow plaque when DES was implanted. DES was generally buried under neointima without thrombus formation in both of 2 lesions observed at 1.5 years.
Conclusion: Sirolimus DES, compared with BMS, was poorly covered by neointima and was accompanied by thrombus especially when there was yellow plaque under stent. Longer anti-thrombotic therapy may be required after DES implantation.