Synergistic effects of plaque geometry and composition on coronary hemodynamics and mechanical stability: a multiscale computational study

Cardiovascular disease remains the leading cause of global mortality, with the rupture of vulnerable atherosclerotic plaques accounting for the majority of acute myocardial infarctions. While plaque morphology and composition are well recognized as critical determinants of vulnerability, their combined effects across clinically relevant stenosis severities (50%-80%) remain incompletely understood. To address this gap, this study aimed to systematically investigate the collective influence of plaque geometry (eccentric vs. concentric) and material composition (lipid, fibrous, calcified) on coronary hemodynamics and mechanical plaque stability under identical stenosis conditions. The left anterior descending artery were reconstructed using clinical computed tomography angiography data, and key hemodynamic (wall shear stress [WSS], oscillatory shear index [OSI], relative residence time [RRT]) and structural metrics (plaque von Mises stress and deformation) were quantified via coupled computational fluid dynamics and fluid-structure interaction simulations. The results demonstrated that eccentric plaques induced significantly more pronounced asymmetric flow disturbances, steeper WSS gradients, and higher RRT values compared to concentric geometries, particularly at higher stenosis severities; notably, at 70% stenosis, the mean RRT of eccentric plaques (0.108 65) was nearly double that of concentric plaques (0.056 86), and eccentric plaques exhibited a unique low-oscillatory shear environment with upstream mean OSI reduced to 0.141 01, whereas concentric plaques showed upstream mean OSI elevated to 0.256 07. Compositionally, lipid-rich regions experienced the greatest deformation, highlighting their role as mechanical 'weak spots,' whereas calcified areas showed minimal deformation but generated interfacial stress concentrations. These findings elucidate the synergistic interaction between plaque geometry and composition in modulating coronary hemodynamics and mechanical integrity, with eccentric morphology exacerbating adverse biomechanical conditions as stenosis progresses. This study provides a novel, multiscale biomechanical framework for assessing plaque vulnerability and informs the development of personalized intervention strategies tailored to specific plaque characteristics.