PURPOSE: Frequency-domain optical coherence tomography (FD-OCT) is a high-resolution imaging tool (~10-15μm), which enables near-histological in-vivo images of the coronary vessel wall. The use of the technique is increasing, both for research- and clinical purposes. This study sought to investigate the intra- and interobserver reliability, as well as the intra-catheter reproducibility of quantitative FD-OCT-assessment of morphometric stent parameters and qualitative FD-OCT-evaluation of strut coverage in 10 randomly selected 6-month follow-up Nobori® biolimus-eluting stents (N-BESs).
METHODS: Ten N-BESs (213 cross sectional areas (CSAs) and 1897 struts) imaged with OCT 6months post-implantation were randomly selected and analyzed by 2 experienced analysts, and the same 10 N-BESs were analyzed by one of the analysts 3months later. Further, 2 consecutive pullbacks randomly performed in another 10 N-BESs (219 CSAs and 1860 struts) were independently assessed by one of the analysts.
RESULTS: The intraobserver variability with regard to relative difference of mean luminal area and mean stent area at the CSA-level was very low: 0.1%±1.4% and 0.5%±3.2%. Interobserver variability also proved to be low: -2.1%±3.3% and 2.1%±4.6%, and moreover, very restricted intra-catheter variation was observed: 0.02%±6.8% and -0.18%±5.2%. The intraobserver-, interobserver- and intra-catheter reliability for the qualitative evaluation of strut coverage was found to be: kappa (κ)=0.91 (95% confidence interval (CI): 0.88-0.93, p<0.01), κ=0.88 (95% CI: 0.85-0.91, p<0.01), and κ=0.73 (95% CI: 0.68-0.78, p<0.01), respectively.
CONCLUSIONS: FD-OCT is a reproducible and reliable imaging tool for quantitative evaluation of stented coronary segments, and for qualitative assessment of strut coverage.