Does low and oscillatory wall shear stress correlate spatially with early atherosclerosis? A systematic review

Abstract

Low and oscillatory wall shear stress is widely assumed to play a key role in the initiation and development of atherosclerosis. Indeed, some studies have relied on the low shear theory when developing diagnostic and treatment strategies for cardiovascular disease. We wished to ascertain if this consensus is justified by published data. We performed a systematic review of papers that compare the localization of atherosclerotic lesions with the distribution of haemodynamic indicators calculated using computational fluid dynamics. The review showed that although many articles claim their results conform to the theory, it has been interpreted in different ways: a range of metrics has been used to characterize the distribution of disease, and they have been compared with a range of haemodynamic factors. Several studies, including all of those making systematic point-by-point comparisons of shear and disease, failed to find the expected relation. The various pre- and post-processing techniques used by different groups have reduced the range of shears over which correlations were sought, and in some cases are mutually incompatible. Finally, only a subset of the known patterns of disease has been investigated. The evidence for the low/oscillatory shear theory is less robust than commonly assumed. Longitudinal studies starting from the healthy state, or the collection of average flow metrics derived from large numbers of healthy vessels, both in conjunction with point-by-point comparisons using appropriate statistical techniques, will be necessary to improve our understanding of the relation between blood flow and atherogenesis.

Keywords: Arterial disease; Atherosclerosis; Blood flow; Haemodynamics; Shear stress.

Figure 1

Schematic overview of the various data-processing methods employed in the reviewed articles, illustrated on lesion and WSS maps taken from Cremers et al. and Peiffer et al., respectively. The summarizing table on the right indicates that the correlation between the lesion and haemodynamic distributions, as perceived by the authors of the reviewed articles, increased for increasing levels of data reduction. Note that articles were double counted if multiple analysis techniques were reported.