Hemodynamic Environments for the Progression of Carotid Stenosis: The NHO Carotid CFD Study

BACKGROUND: Hemodynamic stress plays an important role in the development of atherosclerosis. It is difficult to sufficiently predict the progression of atherosclerosis and consequent stenosis based on known risk factors alone. This may be partly because the hemodynamic environments that promote stenosis progression remain unclear. The carotid bifurcation is the preferred site of atherosclerosis. In this prospective observational study, we sought to identify hemodynamic predictors of carotid stenosis progression. METHODS: Computational fluid dynamics analysis was performed using arterial geometry and flow velocity specific to individual patients. Hemodynamic metrics were compared by multivariate analysis between the presence or absence of stenosis progression, using known risk factors as confounding factors. RESULTS: A total of 545 patients were enrolled, and 361 stenotic arteries in 313 patients were analyzed, 38 of which had progressive stenosis. Among the carotid arteries with 30% to 55% area stenosis, those with stenosis progression had significantly lower time-averaged wall shear stress (WSS; odds ratio [OR], 0.078 [95% CI, 0.012–0.492]; P =0.0067) distal to the stenosis site and significantly higher oscillatory shear index (OR, 2.37 [95% CI, 1.17–4.82]; P =0.016). Among carotid arteries with 56% to 70% stenosis, those with stenosis progression had significantly higher time-averaged WSS (OR, 2.36 [95% CI, 1.19–4.72]; P =0.014) and transverse WSS (OR, 3.03 [95% CI, 1.45–6.34]; P =0.0033), a metric for multidirectional WSS disturbance, at the stenotic site and significantly higher transverse WSS (OR, 2.30 [95% CI, 1.20–4.42]; P =0.012) at the distal site. Arteries with 71% to 99% stenosis and stenosis progression had significantly higher oscillatory shear index (OR, 1.91 [95% CI, 1.05–3.47]; P =0.033) at the distal site. CONCLUSIONS: These data suggest the specific hemodynamic environments involved in the stenosis progression at bifurcation and that hemodynamic risk for stenosis progression differs depending on the degree of stenosis. Combining these hemodynamic predictors with known risk factors may allow a more accurate selection of cases at high risk of progression.