Abstract 4543: Heterogeneity of Coverage and the Color of Neointima After Drug-eluting Stent Implantation: Observation by Angioscopy and OCT
Background: Drug-eluting stents (DES) are susceptible to late thrombosis due to delayed re-endothelialization over the stent struts, which may result in the fatal situation. Coronary angioscopy can semi-quantitatively visualize the presence of neointima coverage and thrombus, whereas optical coherence tomography (OCT) can provide a detailed representation of neointima thickness, in the entire vessel circumference. Therefore, we performed a comparative serial investigation of Sirolimus-eluting stent (SES) and Paclitaxel-eluting stent (PES) using these imaging modalities
Method: For 8 to 12 month (10.3 month average) follow up, 52 lesions (SES 24, PES 28) in 52 DES patients were imaged with angioscopy and OCT simultaneously. Stent malapposition, presence or absence of thrombus and neointimal proliferation (grade 0 to 3) was then observed. Heterogeneity index (HI) of neointima was calculated by OCT as: SD/average thickness of neointima.
Results: Angioscopy showed that the grade of neointimal coverage in PES was significantly greater than that in SES (PES1.59, SES: 1.0, P<0.05). The difference of neointima grade between minimum and maximam grade in PES was greater than in SES. In-stent yellow grade of neointima in SES was significantly greater than in PES (SES: 1.16, PES: 0.66, p<0.05). Thrombus was identified in 4 segments in both groups by angioscopy. All thrombi were observed associated with yellow plaque. OCT revealed 11 malappositions in SES and 9 in PES, 12 thrombi in SES and 8 thrombi in PES were detected. The thickness of neointima in PES was much greater than in SES, however, the heterogeneity of neointima was not different in between both groups. (SES: 121.3±7.1μm, HI:0.89, PES:219.9±10.4μm, 121.3±7.1μm, HI: 0.56, p=0.23).
Conclusion: Neointima was confirmed in the majority of the stent, but the thickness was thinner in SES compared to PES. However, heterogeneity of neointima was comparable between SES and PES by OCT. Furthermore, higher yellow grade of neointima were identified in SES by angioscopy, which was a possible cause for stent thrombosis. These data suggested that SES had a neointima with different tissue characteristics, which might provide different, rate of late thrombosis, rather than the heterogeneity of neointima proliferation.