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

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 mum. 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 microm. Bland-Altman plots demonstrated a low intraobserver and interobserver variability for intimal thickness, with repeatability coefficients 26.7 mum and 24.1 mum, 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.