Accuracy of Optical Coherence Tomography in the Evaluation of Neointimal Coverage After Stent Implantation

Abstract

This study aimed to evaluate the accuracy of optical coherence tomography (OCT) in analyzing the neointimal response to several drug-eluting stent (DES) types by comparing OCT images acquired in vivo with corresponding histological specimens using a nondiseased porcine injury model. Optical coherence tomography is emerging as a promising endovascular imaging tool for the evaluation of neointimal response after DES implantation. A total of 84 stents were implanted-22 ML Vision (Abbott Vascular, Santa Clara, California), 22 Xience V (Abbott Vascular), 20 Endeavor (Medtronic, Minneapolis, Minnesota), and 20 Taxus Liberté (Boston Scientific, Natick, Massachusetts) stents-in normal porcine coronary arteries and were harvested at 28 (n=42) and 90 (n=42) days, with the different stent types equally distributed between the 2 follow-up periods. At termination, morphometric evaluation using OCT imaging was performed in all stented arteries. Histological morphometric analysis was performed and correlated with OCT. A total of 622 OCT-histology matched frames acquired from all stent designs were analyzed. The luminal (13.7%) and stent (6.1%) areas were consistently larger by OCT compared with histology. The mean neointimal thickness was very similar between techniques (approximately 3.27% variation). There was a high correlation between OCT and histology for the evaluation of neointimal area (R2=0.804), luminal area (R2=0.825), and neointimal thickness (R2=0.789). Correlation for total stent area was poor (R2=0.352). Although the proportion of individual struts determined to be uncovered by OCT and histology was similar, there was significant variation in the estimation of strut coverage between OCT and histology when the neointimal thickness was between 20 and 80 microm. This variation converged for neointimal thicknesses between 80 and 100 microm. Subtle differences in neointimal formation induced by current DES can be reproducibly analyzed in vivo by OCT. However, OCT measurement of stent area seems to have less correlation with histology.