Quantitative analysis of intracoronary optical coherence tomography measurements of stent strut apposition and tissue coverage

doi:10.1016/j.ijcard.2008.11.204

International Journal of Cardiology

Volume 141, Issue 2, 28 May 2010, Pages 151-156

https://doi.org/10.1016/j.ijcard.2008.11.204 Get rights and content

Abstract

Background

The introduction of optical coherence tomography (OCT) as an intracoronary imaging modality has allowed accurate assessment of strut apposition and neointimal tissue coverage. This study set out to assess the inter and intraobserver variability of measurements of acute stent apposition and strut tissue coverage using OCT.

Methods

Thirty patients were studied (14 immediately after stent implantation and 16 during follow-up angiography [mean of 4.7 ±2.8 months]) using OCT (LightLab, Westford, Massachusetts, US). Data analysis was performed by 2 experienced observers. Struts were classified as “embedded", “protruding" or “malapposed" to the vessel well and recorded as percentage of total struts. Intimal coverage at follow-up was measured as the thickness of tissue covering each strut expressed in μm. Intra and interobserver variability was assessed by Bland-Altman plots and by calculation of the intraclass correlation coefficient (ICC).

Results

An average of 3967 struts was examined by each observer and, overall, 53.7% of struts was embedded, 36.4% protruding and 9.9% malapposed. Low intraobserver variability for all measures of strut apposition was found, with repeatability coefficients that ranged between 5.1% and 9.3% and ICC exceeding 95% in all cases. Interobserver variability was also low (repeatability coefficients 6.6–10.8 and ICC > 91.3%). Mean intimal thickness in the follow-up group was 172.5 µm. Bland-Altman plots demonstrated a low intraobserver and interobserver variability for intimal thickness, with repeatability coefficients 26.7 μm and 24.1 μm, respectively and ICC exceeding 98.6% for both.

Conclusions

Low intra and interobserver variability can be expected when analyzing OCT data for stent apposition and tissue coverage. This supports the validity of OCT as a clinical and research tool in the setting of intracoronary stent imaging.

Section snippets

Methods

A total of 30 patients were prospectively included in this study. OCT was performed immediately after stent deployment in 14 patients and on follow-up angiography in a separate group of 16 patients, using the LightLab system (Westford, Massachusetts, US). Blood clearance was achieved using a proximal occlusion balloon (Helios, Goodman, Japan) with intra-coronary flush of lactated Ringer's solution through the end-hole of the balloon catheter (flow rate 0.6–0.9 ml/s) during simultaneous image

Acute stent strut apposition

Clinical and angiographic and procedural characteristics of the 14 patients having OCT immediately following stent implantation are shown in Table 1. The target vessel was the left anterior descending artery (LAD) in 50%, left circumflex artery (LCx) in 21.4% and the right coronary artery (RCA) in 28.6%. OCT was performed uneventfully in all cases.

A mean of 3930 struts were examined by observer 1 and 4042 by observer 2. The average percent embedded, protruding and malapposed struts for observer

Discussion

This is the first systematic study to evaluate inter and intra-observer variability for both acute stent apposition and late tissue stent strut coverage using OCT. With its high resolution, OCT permits a detailed assessment of coronary structures while giving unique insights into tissue responses following stent implantation. Our study shows that OCT analysis gives highly reproducible data for both the assessment of acute stent strut apposition and late strut tissue coverage.

Conclusions

Low intra and interobserver variability can be expected when analyzing intracoronary derived OCT data for stent strut apposition and intimal coverage. This supports the validity of OCT as a clinical and research tool in the setting of intracoronary stent imaging.

Acknowledgement

The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology [21].

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Although the application of OCT for examining plaque features is well established, there is a gap in the existing knowledge on two important issues. Firstly, OCT in clinical practice is commonly performed only post stenting to optimise percutaneous coronary intervention (PCI) results [5,6]. Plaque features behind struts are routinely excluded from the analysis of OCT registries aimed at examining clinical and procedural outcomes [7].
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Optical coherence tomography (OCT) is widely used for evaluation of healing response to stent implantation. We sought to test the agreement between the 1-mm and 0.6-mm sampling intervals for assessment of the percentage of uncovered and malapposed struts by OCT.
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At a median followup of 60 [8] days, 694 crosssections (7603 struts) and 1138 crosssections (12,331 struts) were analysed at 1mm and at 0.6mm intervals, respectively. The median [IQR] percentage of uncovered struts was 3.27% [11.1] versus 3.38% [9.76] (p = 0.001), and the mean (± SD) percentage was 7.69 ± 9.99% versus 6.27 ± 8.14% (p = 0.004), for the 1mm sampling interval versus the 0.6mm sampling interval analysis, respectively; the median percentage of malapposed struts was 0.42% [2.04] versus 0.12% [1.63], respectively, (p = 0.003). The intraclass correlation coefficient between the two observers for the percentage of uncovered struts was 0.95.
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Quantitative analysis of intracoronary optical coherence tomography measurements of stent strut apposition and tissue coverage

Abstract

Background

Methods

Results

Conclusions

Section snippets

Methods

Acute stent strut apposition

Discussion

Conclusions

Acknowledgement

Am J Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

Int J Cardiol

Optical coherence tomography to assess malapposition in overlapping drug-eluting stents

EuroIntervention

Relationship between a systemic inflammatory marker, plaque inflammation, and plaque characteristics determined by intravascular optical coherence tomography

Arterioscler Thromb Vasc Biol

Optical coherence tomography for imaging the vulnerable plaque

J Biomed Opt

In vivo characterization of coronary atherosclerotic plaque by use of optical coherence tomography

Circulation

Quantification of macrophage content in atherosclerotic plaques by optical coherence tomography

Circulation