Stent evaluation with optical coherence tomography

Abstract

Optical coherence tomography (OCT) has been recently applied to investigate coronary artery disease in interventional cardiology. Compared to intravascular ultrasound, OCT is able to visualize various vascular structures more clearly with higher resolution. Several validation studies have shown that OCT is more accurate in evaluating neointimal tissue after coronary stent implantation than intravascular ultrasound. Novel findings on OCT evaluation include the detection of strut coverage and the characterization of neointimal tissue in an in-vivo setting. In a previous study, neointimal healing of stent strut was pathologically the most important factor associated with stent thrombosis, a fatal complication, in patients treated with drug-eluting stent (DES). Recently, OCT-defined coverage of a stent strut was proposed to be related with clinical safety in DES-treated patients. Neoatherosclerosis is an atheromatous change of neointimal tissue within the stented segment. Clinical studies using OCT revealed neoatherosclerosis contributed to late-phase luminal narrowing after stent implantation. Like de novo native coronary lesions, the clinical presentation of OCT-derived neoatherosclerosis varied from stable angina to acute coronary syndrome including late stent thrombosis. Thus, early identification of neoatherosclerosis with OCT may predict clinical deterioration in patients treated with coronary stent. Additionally, intravascular OCT evaluation provides additive information about the performance of coronary stent. In the near future, new advances in OCT technology will help reduce complications with stent therapy and accelerating in the study of interventional cardiology.

Keywords: Optical coherence tomography; coronary artery disease; stent.

Fig. 1

Representative images of well-apposed vs. malapposed struts. Optical coherence tomography shows well-apposed struts with complete coverage 9 months after drug-eluting stent implantation (A), whereas some struts (arrowheads) show incomplete stent apposition and uncovered portions to the lumen (B).

Fig. 2

Strut coverage of drug-eluting stent (DES) over time. A dot represents each of the studies in Table 1, except for Bayesian hierarchical models. A curved line represents estimated change of uncovered strut after DES implantation. Usage of sirolimus-eluting stent and incomplete stent apposition increases the risk of delayed coverage after DES implantation.

Fig. 3

Various patterns of neointimal tissue. (A) Homogeneous pattern, (B) heterogeneous pattern, (C) layered pattern, (D) lipid-laden neointima, (E) neointima with calcification.

Fig. 4

Contour plot of strut coverage after drug-eluting stent implantation, using optical coherence tomography. The contour plot shows detailed information about the position and coverage of stent strut, in which the circumferential arc is plotted along the X axis and the stent length is plotted along the Y axis. Blue circles represent uncovered struts, red circles represent malapposed struts, and orange circles represent struts crossing over a side-branch vessel.