In vitro analysis of coronary atheromatous lesions by intravascular ultrasound; reproducibility and histological correlation of lesion morphology.

AIM To determine the reproducibility and histological correlation of qualitative intravascular ultrasound imaging of atheromatous coronary arteries using the recently proposed European Society of Cardiology classification of plaque composition in conditions approximating the clinical setting. METHODS Atheromatous lesions (n=21), identified from 30 post-mortem human coronary arteries, were imaged using intravascular ultrasound in a pulsatile flow system which simulates coronary flow. Fifty sites (21 x minimum lumen area and 29 x distal reference sites) were selected independently by two observers from continuous video recordings. Atheromatous plaque was classified as echodense, echolucent, heterogeneous or calcified by each observer and by one observer on separate occasions. Arterial specimens were histologically sectioned at these sites and similarly analysed by a third observer blinded to the intravascular ultrasound appearances. RESULTS Overall inter- and intra-observer reproducibility for plaque-type (Kappa 0.87[0.80-0.94] and 0.89[0. 85-0.93 respectively]) and focal calcification (0.78[0.74-0.82] and 0.88[0.84-0.92]) was high. Differences in site selection significantly influenced reproducibility particularly at reference sites. Agreement for overall plaque type between intravascular ultrasound and histology occurred in 89% of sites (Kappa 0.73[0.69-0. 77]). Specificity and positive predictive values for individual plaque types were greater than 90%. CONCLUSION Using modern intravascular ultrasound technology in an in vitro system which approximates the clinical setting the proposed ESC classification of plaque composition by intravascular ultrasound is reproducible and correlates well with histology. It should therefore perform reliably in diagnostic intravascular ultrasound examinations and in the guidance of percutaneous coronary interventions.