Serial optical coherence tomographic observation of neointimal tissue after bare-metal and everolimus-eluting stent in porcine coronary artery

Abstract

Objectives: To evaluate serial changes in neointimal tissues between everolimus-eluting stent (EES) and bare-metal stent (BMS) in normal porcine coronary artery using optical coherence tomography (OCT). Background: Serial changes in neointimal tissue after drug-eluting stent implantation have not been sufficiently investigated using OCT. Methods: Serial (1, 3 and 6 months follow-up after stent implantation) OCT examinations were performed in 15 swine with 15 BMS- and 15 EES-treated lesions in normal porcine coronary arteries. Qualitative and quantitative changes of neointimal tissues in stented segments with maximal percentage of cross-sectional area stenosis of neointima at 1 month follow-up were serially evaluated. Results: In BMS-implanted lesions, neointimal volume did not significantly change from median 6.5 (interquartile (IQR) 4.7-7.6) mm3 to 6.9 (IQR 4.6-8.2) mm3, 6.4 (IQR 4.3-7.4) mm3 at 1, 3 and 6 months follow-up (p=0.882). At different time point of 1, 3 ant 6 months, neointimal tissue appearance was mainly the homogeneous pattern (80.0%, 93.3% and 100%, respectively), while the layered pattern decreased (20.0%, 6.7% and 0%, respectively). On the other hands, in EES-implanted lesions, neointimal volume increased median 4.8 (IQR 4.1-7.6) mm3 to 9.8 (IQR 5.7-15.1) mm3 between 1 and 3 months (p<0.001), but significantly decreased to 8.6 (IQR 6.0-11.2) mm3 between 3 and 6 months (p=0.007). Between 1 and 3 months, the layered pattern of neointima increased from 26.7% to 66.7%, but deceased to 20.0% between 3 and 6 months. Conclusion: In this animal model, this OCT study showed that EES had a biphasic pattern of neointimal amounts which was correlated with change of neointimal morphology.