Serial Optical Coherence Tomography Evaluation at 6, 12, and 24 Months After Biolimus A9-Eluting Biodegradable Polymer-Coated Stent Implantation

Abstract

BackgroundThe Nobori (Terumo Corporation, Tokyo, Japan) is a biolimus A9-eluting stent (BES) featured with a biodegradable polymer coated on the abluminal side only. We previously reported that favourable vessel healing was achieved at 6-12 months after BES implantation. However, detailed long-term vessel reaction after BES deployment is unclear. MethodsTwenty-two BESs were serially evaluated using optical coherence tomography (OCT) at 6, 12, and 24 months after stenting. Average neointimal thickness, uncovered struts, and neointimal unevenness score (each cross-section as maximum neointimal thickness in 1 cross section divided by the average neointimal thickness of the same cross-section) were manually measured. In addition, we evaluated the percentage of struts with peri-strut low-intensity area (a region around stent struts that homogenously showed less intensity than the surrounding tissue, which suggests fibrin deposition or impaired neointima maturation), thrombi, and atherogenic neointimas (neointimas containing a diffuse border and poor-signal region with invisible struts due to marked signal attenuation). ResultsSerial OCT observation revealed a small gradual increase in neointimal thickness from 6 to 24 months (73 ± 24 μm; 81 ± 26 μm; and 108 ± 35 μm, respectively, P = 0.001) with a nonsignificant decrease in the lumen area (6.36 ± 1.98 mm2; 6.18 ± 2.04 mm2; and 5.87 ± 2.06 mm2; P = 0.72). Frequency of uncovered struts (3.89 ± 3.91%; 1.55 ± 1.63%; and 0.23 ± 0.67%; P = 0.001), neointimal unevenness score (1.95 ± 0.18% to 1.86 ± 0.19% to 1.78 ± 0.17; P = 0.012), percentage of thrombi (5%, 0%, and 0%; P = 0.37) and peri-strut low-intensity area (6.8%, 5.1%, and 1.6%; P = 0.017) decreased from 6 to 12 and 24 months. Atherogenic neointima was not observed in the event-free OCT cohort. ConclusionsThe Nobori stent achieved acceptable long-term vessel healing, mostly without adverse vessel reactions.