Plaque and shear stress distribution in human coronary bifurcations: a multislice computed tomography study

Early atherosclerosis is located in low wall shear-stress (WSS) regions, however plaques are also found in the high WSS sensing flow divider walls of coronary bifurcations. We assessed the plaque distribution and morphology near bifurcations non-invasively with 64-slice computed tomography in relation to the WSS distribution.

We inspected 65 cross-sections near coronary bifurcations for the presence of plaque. Cross-sections were divided into four equal parts, which we numbered according to expected levels of WSS, with part I the lowest WSS (outer wall) and increasing WSS's in part II (inner bend), III (outer bend) and IV (flow divider). Of the cross-sections 88% had plaque. Of all parts I, 72% contained plaque. This was 62%, 38% and 31% in parts II, III and IV. In cross-sections with only 1 or 2 parts inflicted, plaque was found in part I and/or II in 94%. In 93% of the cross-sections with the flow divider inflicted, parts I and/or II were also inflicted. Plaque was never found exclusively in the flow divider part IV.

We demonstrated that plaque is mostly present in low WSS regions, whereas plaque in high WSS regions is accompanied by plaque in adjacent low WSS regions. It is therefore plausible that plaque grows from the outer wall (low WSS) of the bifurcation towards the flow divider (high WSS).