Wall shear rate and energy loss coefficient measures using conventional Doppler ultrasound do not predict carotid plaque progression

Background: The rate of carotid plaque progression is believed to be related to blood flow hemodynamics and shear stress. Our objective was to determine if wall shear rate (WSR) and the energy loss coefficient (ELC) measured by Doppler ultrasound could predict atherosclerotic carotid disease progression. Patients and methods: Patients at a large tertiary center with an initial ultrasound between 2016 and 2018 with a significant carotid plaque were included if they had at least one 6 months follow-up comparative study. Stenosis progression was assessed according to the NASCET (The North American Symptomatic Carotid Endarterectomy Trial) percentage criterion. Results: The average annual progression rate for the 74 plaques included was 5.7% NASCET per year. We identified 18 plaques with ≥10% NASCET progression and 56 plaques without significant progression <10% NASCET. Among the plaques with progression, only four plaques had progression greater than 20% NASCET. Median WSR was 6266 s^-1 [5813-8974] in plaques with progression and 6564 s^-1 [5285-8766] in stable plaques (p=0.643). Median ELC was 3.86 m² [2.78-5.53] in plaque with progression and 4.32 m² [3.42-6.81] in stable plaques (p=0.296). Conclusions: Although it is a widely accepted hypothesis that shear stress and hemodynamics of the carotid bifurcation contribute to plaque progression, we found that WSR and ELC estimated by Doppler ultrasound do not reliably predict atherosclerotic plaque progression in the carotid artery. Other ultrasound modalities, such as 3D imaging, may be used to assess the influence of plaque geometry and hemodynamics in plaque progression.