Exploring the Interplay of Left Coronary Tree Anatomy and Haemodynamics: Implications for Plaque Formation

The link between atherosclerosis and blood flow-induced haemodynamic luminal shear stresses is well established. However, this understanding has not been translated into clinical practice because of the interdependent effects of the complex coronary anatomy and a multitude of potential haemodynamic metrics, which have been challenging to delineate. Thus, this study aims to identify anatomical and haemodynamic differences in coronary trees at different stages of stenoses. A total of 39 left coronary trees were considered, which are publicly available. Each coronary tree was dissected into bifurcations and non-bifurcating segments for comparisons. We calculated a full set of anatomical metrics and performed transient flow simulations to solve the normalised luminal area exposed to Low Time-Average Endothelial Shear Stress (%LowTAESS), High Oscillatory Shear Index (%HighOSI), and High Relative Residence Time (%HighRRT). We statistically investigated the differences between non-stenosed (n=20, Diameter Stenosis DS=0%), moderately (n=12, 0%=70%) stenosed cases, whereby p<0.05* is considered significant. Only the average curvature and %HighOSI differed between the non-stenosed, and moderately or severely stenosed for the coronary trees (p=0.024* and p<0.001*), and non-bifurcating segments (p=0.027* and p<0.001*). %LowTAESS@0.5Pa and %HighRRT@2.5Pa-1 significantly differed between moderately (0%=70\%) stenosed trees (p=0.009* and p=0.012*). Our findings suggest curvature and potentially %HighOSI being critical factors in coronary plaque onset in non-bifurcating segments, whereas %LowTAESS and %HighRRT affect plaque progression after onset.