Comparison of neointimal coverage and extra-stent lumen between sirolimus and everolimus-eluting stent using optical coherence tomography.

The external lumen of a stent [defined as extra-stent lumen (ESL)] assessed by optical coherence tomography (OCT) may be related to the risk of thrombus formation after sirolimus-eluting stent (SES) implantation. An everolimus-eluting stent (EES) might provide relatively minimal inflammatory reaction and appropriate neointimal coverage. The purpose of this study was to compare the neointimal thickness and ESL between SES and EES. Patients who underwent OCT examination more than 7 months after either SES or EES implantation were enrolled. Stent area (SA), lumen area (LA), neointimal area (NIA) and neointimal thickness (NIT) of each strut were measured at 1-mm intervals between stented segments. The area, angle (summation per cross-section) and depth (maximum distance from adjacent vessel surface to the outline of stent) of ESL were analyzed. A total of 49 lesions were included (SES n = 20, EES n = 29). Mean follow-up period was 11 months. A total of 998 cross-sections and 9874 struts were analyzed. There were no differences in stent area, lumen area and neointimal area (SA: 6.01 ± 1.60 vs. 6.02 ± 1.40 mm(2), p = 0.572, LA: 5.37 ± 1.52 vs. 5.29 ± 1.34 mm(2), p = 0.692, NIA: 0.64 ± 0.49 vs. 0.72 ± 0.37 mm(2), p = 0.493). Mean NIT of SES and EES were 0.11 ± 0.05 and 0.10 ± 0.05 mm, respectively (p = 0.367). Conversely, area, angle and depth of ESL in SES group were significantly greater than those in EES group (0.20 ± 0.39 vs. 0.03 ± 0.09 mm(2), p < 0.001, 56.2 ± 59.1° vs. 20.1 ± 41.9°, p < 0.001, 0.10 ± 0.09 vs. 0.03 ± 0.03 mm, p < 0.001). OCT showed that the efficacy of neointimal growth suppression is similar between SES and EES, whereas the adverse vascular response after EES implantation is smaller than that after SES implantation.

Serial three-dimensional optical coherence tomography assessment of strut coverage and intraluminal structures after drug-eluting stent implantation.

Understanding of intraluminal structure and distribution of uncovered struts after drug-eluting stent implantation are limited by only 2-dimensional (2D) optical coherence tomography (OCT) images. We compared tissue coverage with 3-dimensional (3D) OCT and 2D quantitative analyses, and changes in intraluminal structure immediately after (baseline) everolimus-eluting stent (EES) implantation and at follow-up. The 2D analyses of uncovered struts ratio and tissue coverage thickness at a 0.5-mm interval were compared to 3D-OCT images and visually classified for the degree of tissue coverage. The difference in tissue coverage at baseline and follow-up after EES implantation was evaluated with tissue coverage scores (TCS) calculated by the 3D-OCT classification (Grade 0-3). 3D-OCT classifications were negatively correlated with uncovered-to-total struts (r = -0.864, P < 0.001) and positively correlated with tissue coverage thickness (r = 0.905, P < 0.001). Follow-up TCS was greater than baseline TCS (0.2 ± 0.4 vs. 1.4 ± 0.5, P < 0.001). Moreover, changes in intraluminal structures and longitudinal distribution of uncovered struts were assessed. Incomplete stent appositions, in-stent dissections, and thrombi were decreased at follow-up, indicating progressive arterial healing. The distribution of uncovered-to-total struts could be assessed by 3D-OCT, which was related to 2D analysis. Significant correlations between 3D-OCT classifications and quantitative analyses were shown. The classification and visual assessment of intraluminal structures by 3D-OCT were useful in evaluating arterial healing after EES implantation.