Abstract 4916: Difference in Neointimal Growth on the Stent Struts Crossing a Side Branch Between Sirolimus-Eluting Stent and Bare-Metal Stent: An Optical Coherence Tomography Analysis
Background: A bifurcation lesion has been demonstrated to be the high risk lesion for late stent thrombosis (LST) following drug-eluting stent implantation, resulting from disturbed laminar blood flow and delayed endothelialization of unapposed stent struts. We examined differences in neointimal growth on the stent struts crossing a side branch between sirolimus-eluting stent (SES) and bare-metal stent (BMS) using optical coherence tomography (OCT)..
Methods and Results: Of the 41 stents (34 cases) implanted across side branches, 70 struts of 28 SES and 23 struts of 13 BMS, which crossed over a side branch, were analyzed 9 months after stent implantation using OCT. Ten of 28 SES were also analyzed after 3 months. Neointimal growth around the unapposed struts, extending from the adjacent vessel wall, was classified into either complete or incomplete coverage of struts. Neointimal thickness (NIT) on struts was also measured. At 9-month follow-up, complete coverage was observed in 45 struts of SES (64.3%) and in 21 struts of BMS (91.3%) (p<0.05). Mean NIT for SES was significantly less than that for BMS (0.06 ± 0.05 mm vs 0.10 ± 0.07 mm, p < 0.01). Of 26 struts of 10 SES analyzed at both 3- and 9-month follow-up, complete coverage was observed in only 5 struts (19.2%) at 3 months, and in 18 struts (69.2%) at 9 months (p<0.01). Thrombus at the orifice of a side branch was identified in 1 SES at 3 months.
Conclusions: Neointimal growth extending from the adjacent vessel wall was observed around the unapposed struts crossing a side branch by OCT. Neointimal coverage of unapposed struts was delayed in SES in comparison with BMS, which would give an explanation for the cause of LST in the bifurcation lesion.