Optical Coherence Tomography Imaging: Novel Insights into the Vascular Response After Coronary Stent Implantation

Abstract

Optical coherence tomography (OCT) is a high-resolution imaging technique that is increasingly used for intracoronary imaging to characterize coronary atherosclerotic plaques and vascular responses after coronary stent implantation. Introduction of optical frequency-domain imaging (OFDI; second generation OCT) has simplified practical use of this novel imaging modality resulting in a more widespread availability in interventional cardiology. Here we highlight recent insights into the acute and chronic vascular response after coronary stent implantation by OCT imaging. OCT provides cross-sectional images with approximately 10-fold higher resolution as compared to intravascular-ultrasound (IVUS), allowing for precise evaluation of tissue coverage and malapposition of coronary stent struts. More than 30 studies using OCT to compare vascular responses to different stents have now been reported. Recent studies have examined the relation between OCT-image characteristics and tissue composition around stent struts. OCT is used for evaluation of novel stent concepts, such as bioengineered stents and bioabsorbable stents, where it provides more accurate information than IVUS. While intracoronary OCT imaging is further developed, including faster 3D-OCT-image-reconstruction, larger OCT studies/registries with standardized analysis will provide more insights into clinical implications of observations from OCT-imaging after coronary stent implantation.

Fig. 1

The high resolution of OCT (axial resolution 10–15 μm) allows for detection of thin layers of stent strut coverage and sensitive detection of stent strut apposition/malapposition: a, OCT cross-sectional image demonstrating well apposed stent struts; b, OCT image demonstrating stent struts covered with a thin neointima layer that is below the IVUS axial resolution (100 μm). Asterisk indicates OCT catheter. ST, stent strut

Fig. 2

Very late in-stent thrombosis after DES implantation. a, malapposed stent struts, that are at least partially uncovered (red arrows); b, magnification of malapposed stent struts at least partially uncovered or covered by protruding white thrombi. Asterisk indicates OCT catheter. ST, stent strut

Fig. 3

This image illustrates potential aspects of why an acute coronary syndrome may predispose to an impaired stent healing: a, Red thrombus in the culprit lesion of the proximal segment of RCX in a patient with NSTEMI; b, After stent implantation stent struts with underlying and protruding thrombi are to be seen likely promoting malapposition (red arrows). Asterisk indicates OCT catheter

Fig. 4

In stent dissection and edge dissection after coronary stent implantation that can be detected by OCT and frequently would not be seen by angiography or IVUS (red arrows). Asterisk indicates OCT catheter