Abstract 4609: Incomplete Neointimal Coverage Persists Beyond 4 Years After Sirolimus-Eluting Stent Implantation: Angioscopic Follow-up Study in Patients
Background- Several large cohort studies up to 4 years revealed low but persistent risk of very late stent thrombosis following drug-eluting stent implantation. This may be attributed to incomplete neointimal coverage following stenting. Using angioscopy, we examined the neointimal characteristics on sirolimus-eluting stent (SES) 4 years after implantation.
Methods-Angioscopy was performed for 20 SES (baseline disease: de novo lesio n=18; in-stent restenosis of bare-metal stent=2) in 13 patients (age 74±5 years, male 85%). Neointimal coverage (NIC), presence of thrombus, and yellow plaques underneath the stent were examined. NIC was graded as: grade 0, stent struts exposed; grade 1, struts bulged into the lumen, although covered; grade 2, struts embedded by the neointima, but translucent; grade 3, struts fully embedded and invisible. NIC was defined heterogeneous when difference in the grades equal to or greater than one was present. Exposed struts were scored as: exp 0, no grade 0; exp 1, grade 0 in limited areas; exp 2, NIC grade 0 50%, but not completely; exp 4, struts completely exposed.
Results- The majority of SES showed dominant NIC of grade 1 (Figure⇓). Sixty-five % showed heterogeneous NIC, 55% of which showed heterogeneity of 1 grade. Thrombus was detected in 30% of SES; all thrombi were red, mural and were detected at the site of grade 0–1. Yellow plaques were detected in 75% of SES. Exposed struts were detected in six SES (30%); 20% of these showed exp 1, and 10% showed exp 2.
Conclusion-The majority of SES demonstrated low grade neointimal coverage even after 4 years in asymptomatic patients, some of which still had partially exposed struts.