The Role of Fluid Mechanics in Coronary Atherosclerotic Plaques: An Up-to-Date Review.

Most acute coronary syndromes are due to a sudden luminal embolism caused by the rupturing or erosion of atherosclerotic plaques. Prevention and treatment of plaque development have become an effective strategy to reduce mortality and morbidity from coronary heart disease. It is now generally accepted that plaques with thin-cap fibroatheroma (TCFA) are precursors to rupturing and that larger plaques and high-risk plaque features (including low-attenuation plaque, positive remodeling, napkin-ring sign, and spotty calcification) constitute unstable plaque morphologies. However, plaque vulnerability or rupturing is a complex evolutionary process caused by a combination of multiple factors. Using a combination of medicine, engineering mechanics, and computer software, researchers have turned their attention to computational fluid mechanics. The importance of fluid mechanics in pathological states for promoting plaque progression, inducing plaque tendency to vulnerability, or even rupture, as well as the high value of functional evaluation of myocardial ischemia has become a new area of research. This article reviews recent research advances in coronary plaque fluid mechanics, aiming to describe the concept, research implications, current status of clinical studies, and limitations of fluid mechanic's characteristic parameters: wall shear stress (WSS), axial plaque shear (APS), and fractional flow reserve (FFR). Previously, most computational fluid dynamics were obtained using invasive methods, such as intravascular ultrasound (IVUS) or optical coherence tomography (OCT). In recent years, the image quality and spatial resolution of coronary computed tomography angiography (CCTA) have greatly improved, making it possible to compute fluid dynamics by noninvasive methods. In the future, the combination of CCTA-based anatomical stenosis, plaque high-risk features, and fluid mechanics can further improve the prediction of plaque development, vulnerability, and risk of rupturing, as well as enabling noninvasive means to assess the degree of myocardial ischemia, thereby providing an important aid to guide clinical decision-making and optimize treatment.