Journal of Invasive Cardiology

ABSTRACT: Background. Optical coherence tomography (OCT) has been increasingly used to evaluate stent apposition following implantation. Since stent struts are visualized as linear structures with strong surface reflection and typical dorsal shadowing, apposition of struts is evaluated by measuring the distance between the strut surface reflection and adjacent vessel surface in consideration of strut thickness. However, there are no data available to validate the measurements of strut thickness by OCT. The aim of this in vitro study is to validate the accuracy of OCT measurement of stent-strut thickness of different commercially available stents in evaluating stent apposition. Methods. We performed the in vitro study after implantation of 5 commonly used stents in a phantom model artery. Stent-strut thickness was measured by a commercially available OCT system and was compared to the manufacturers’ nominal strut-thickness data for each stent. Intra- and interobserver variability were also assessed. Results. A total of 239 stent struts were evaluated. The differences in stent-strut measurements as compared to the manufacturers’ nominal strut thickness data were low. The intra- and interobserver measurement differences were low (6 ± 7 µm, and 6 ± 7 µm, respectively), with high correlation coefficients (r = 0.957 and r = 0.957, respectively; p < 0.0001). Conclusions. This in vitro study demonstrates that OCT analysis measuring stent-strut thickness provides accurate data with high reproducibility, suggesting that assessment of stent-strut apposition using OCT is feasible.

J INVASIVE CARDIOL 2009;21:602–605

Key words: accuracy, reproducibility, stent,

Optical coherence tomography (OCT) is being introduced as a new intravascular imaging modality and is gaining widespread use in the cardiac catheterization laboratory. OCT has a distinct advantage over intravascular ultrasound (IVUS) owing to its higher resolution power, with axial resolution of 10–20 µm and lateral resolution of 20–94 µm. OCT uses a near-infrared light source (1,310 nm), which detects the backscattering of light from superficial structures in the vessel wall. OCT has emerged as a very useful tool to evaluate stent-strut apposition, neointimal tissue quantification and to assess plaque morphology.^1–8

Recently, incomplete stent apposition has been reported following usage of drug-eluting stents (DES), potentially contributing to associated clinical events such as stent thrombosis.⁹ OCT can provide detailed information regarding stent structure and its apposition to the underlying vessel wall; however, strong stent surface reflection with typical dorsal shadowing may make it difficult to evaluate stent apposition (Figure 1). Therefore, stent apposition can be evaluated by measuring the distance between the stent-strut surface reflection and the adjacent visible vessel surface.^3,4,6 During these analyses, the stent-strut thickness information provided by manufacturers must be taken into consideration to precisely quantify true separation of the stent strut from the vessel wall; however, no validation studies have been conducted thus far to evaluate the manufacturers’ stated stent-strut thickness and the accuracy of OCT measurements for various commercially available stent platforms.