Interobserver Variability Between Expert, Experienced, and Novice Operator Affects Interpretation of Optical Coherence Tomography and 20 MHz Intravascular Ultrasound Imaging

Vessel sizing and calcium detection by intracoronary imaging informs optimal strategy during coronary interventions, but image interpretation and analysis software vary considerably between platforms. We compared the interobserver variability of clinicians with a range of experience in assessing co-registered optical coherence tomography (OCT) and 20 MHz solid state intravascular ultrasound (IVUS) vessel/ lumen geometry and quantitative plaque data.Co-registered OCT and IVUS frames at the minimum lumen area (MLA) and 5 frames at 2 mm intervals upstream and downstream were read blinded by an expert, consultant, interventional fellow and registrar to define vessel and lumen sizes, plaque characteristics (arc of calcium and lipid) and presence of OCT-defined thin-capped fibroatheroma (TCFA).Overall, 143 paired frames of OCT and IVUS were analysed. Excellent consistency was seen for all OCT measures of vessel/luminal geometry irrespective of experience (all intraclass correlation coefficients (ICC) >0.89). Inexperience compromised ICC for IVUS (lumen area ICC 0.56; vessel size ICC 0.65) and overestimated lumen size compared to expert (p < 0.001). Calcium arc agreement for OCT and IVUS was equally strong for all but the most inexperienced reader (ICC >0.84). OCT lipid arc agreement was moderate for experienced readers but poor for all grades of reader with IVUS (ICC 0.24-0.43). OCT-TCFA agreement was moderate between expert and consultant (κ = 0.55) and poor for less experienced readers.OCT dimensions are minimally affected by observer experience and more consistent than IVUS. Inexperienced readers oversize with IVUS. Calcium arc is dependably assessed by IVUS and OCT by all but the most inexperienced reader.