Agreement and reproducibility of gray‐scale intravascular ultrasound and optical coherence tomography for the analysis of the bioresorbable vascular scaffold

Abstract

To report the agreement between gray-scale intravascular ultrasound (GS-IVUS) and optical coherence tomography (OCT) in assessing the bioresorbable vascular scaffolds (BVS) structures and their respective reproducibility. BVS are composed of an erodible polymer. Ultrasound and light signals backscattered from polymeric material differs from metallic stents using GS-IVUS and OCT. Forty-five patients included in the ABSORB trial were treated with a 3.0 × 18 mm BVS and imaged with GS-IVUS 20 MHz and OCT post-implantation. Qualitative (ISA, side-branch struts, protrusion, and dissections) and quantitative (number of struts, lumen, and scaffold area) measurements were assessed by two investigators. The agreement and the inter- and intraobserver reproducibility were investigated using the kappa (κ) and the interclass correlation coefficient (ICC). GS-IVUS and OCT agreement was predominantly poor at a lesion, frame, and strut level analysis (κ and ICC <0.4) for qualitative measurements. GS-IVUS demonstrated a reduced ability to detect cross-sections with ISA (4.5% vs. 20.6%), side-branch (SB) struts (6.3% vs. 7.8%), protrusions (3.2% vs. 9.6%), and dissections (0.2% vs. 9.0%) compared with OCT. GS-IVUS reproducibility was poor-moderate (κ and ICC <0.6) except for ISA and SB-struts (κ and ICC between 0.2 and 0.75). OCT showed an excellent reproducibility (κ and ICC > 0.75) except for the assessment of tissue protrusion (κ and ICC between 0.47 and 0.94). GS-IVUS reproducibility was poor-moderate (ICC ≤ 0.5) in assessing the number of struts but excellent with OCT (ICC > 0.85). The reproducibility to assess lumen and scaffold areas was excellent using both techniques (ICC > 0.85). GS-IVUS has a poor capacity to detect qualitative findings post-BVS implantation and its reproducibility is low compared with OCT. The use of GS-IVUS should be limited when assessing lumen and scaffold areas.