In vivo assessment of the relationship between shear stress and necrotic core in early and advanced coronary artery disease

Atherosclerotic plaques develop at low shear stress locations in the arterial tree. However, at a certain moment, plaques encroach into the lumen causing local wall shear stress (WSS) increase. Minimal information is available on the relationship between WSS and plaque composition. We investigated in human coronary arteries in vivo the frequency with which the necrotic core and necrotic core in contact with the lumen are located at either low or high WSS regions in early and advanced plaques.We combined a 3-D reconstruction technique of coronary arteries based on angiography and intravascular ultrasound with IVUS-virtual histology (IVUS-VH) data. With IVUS-VH the necrotic core was determined. The lumen of these 3-D reconstructions served as input for the computational fluid dynamics. Per cross-section the WSS at the regions with major necrotic core and necrotic core in contact with the lumen were compared to the median WSS in the cross-section. Ten human coronary arteries were studied. Only cross-sections with average wall thickness >0.5 mm were included in the analysis. In early plaques (plaque burden <40%), the necrotic core was most frequently located at WSS smaller than the median (61%) contrasting the advanced plaques (plaque burden >40%), being located at WSS higher than the median (60%, p<0.05 Mann-Whitney U test). Necrotic core in contact with the lumen was most often exposed to high WSS, being most pronounced in advanced disease (61%, p<0.05).With the advancement of disease, necrotic core is less often located at low WSS regions, but exposed to high WSS, which is probably the result of lumen narrowing. Necrotic core in contact with the lumen was most frequently exposed to high WSS.