An optical coherence tomography study of neointimal morphology and strut coverage at different time intervals from implantation of biodegradable polymer‐coated sirolimus‐eluting stents

Objectives The aim of the study was to capture the evolution of neointima after implantation of a biodegradable polymer–coated, sirolimus–eluting, cobalt–chromium coronary stent system (BP‐DES). Background Optical coherence tomography (OCT) suggests that in‐stent neointimal morphology influences clinical outcomes after DES implantation. Methods Sixty patients treated with single BP‐DES implantation were examined by quantitative coronary angiography (QCA) and OCT at 3, 6, and 12‐month follow‐up. Results Median late lumen loss by QCA (mm) was 0.04 (IQR 0, 0.08), 0.17 (IQR 0, 0.32), and 0.14 (IQR 0.07, 0.31) at 3, 6, and 12‐month follow‐up respectively (P = 0.03). OCT cross‐section multilevel analysis showed uncovered struts in 3.90%, 1.78%, and 0.02% of struts respectively (P = 0.03). The corresponding malapposition rates were 0.12%, 0.04%, and 0%. Lipid‐rich neointima was observed only at 12‐month follow‐up in one restenotic lesion (0.77% cross‐sections) that was accountable for the only target vessel revascularization. The homogeneous pattern was prevalent at all three time points, but its incidence displayed an upward trend (3 months: 59%; 6 months: 71%; 12 months: 88%) despite no difference in neointimal volume between 6 and 12 months. Conversely, a trend could be observed of decreasing incidence of heterogeneous pattern as the follow‐up length increased. Conclusions In this study of a single‐type BP‐DES, the majority of stent struts were covered within 3 months from implantation. While the quantitative neointimal accumulation plateaued at 6 months with no further significant increase beyond 6 months, the neointima continued to evolve qualitatively and mature along with better strut coverage between 6 and 12 months after implantation.