Brachial artery intima–media thickness and grayscale texture changes in patients with peripheral artery disease receiving supervised exercise training in the PROPEL randomized clinical trial

Abstract

We performed an exploratory analysis to evaluate the effects of a treadmill exercise program on brachial artery (BA) intima–media thickness (IMT) and three BA grayscale ultrasound measures that may indicate subclinical arterial injury. Data were from a clinical trial in individuals with peripheral artery disease who were randomly assigned to treadmill exercise training or attention control. B-mode ultrasonography was performed at baseline and after 26 weeks. BA IMT, grayscale median (GSM), entropy, and gray-level difference statistic-contrast (GLDS-CON) were measured by a single reader. The 184 participants were (mean (SD)) 66.7 (8.2) years old and had an ankle–brachial index of 0.70 (0.18). Exercise training was associated with a 0.01 (0.06) mm (p = 0.025) reduction in BA IMT compared to 0.00 (0.05) mm (p = 0.807) in the control group (between-group p = 0.061). BA GSM, entropy, and GLDS-CON did not change significantly with exercise. Improvements in the 6-minute walk distance correlated with increases in resting BA blood flow (r = 0.23, p = 0.032), flow-mediated dilation (r = 0.24, p = 0.022), diameter (r = 0.29, p = 0.005), entropy (r = 0.21, p = 0.047), and GLDS-CON (r = 0.22, p = 0.041). In a post hoc analysis, BA IMT improved significantly with treadmill exercise training but did not change with attention control; however, the between-group difference did not reach statistical significance. With exercise, improvements in the 6-minute walk distance were associated with improved endothelial function, increased resting blood flow, and BA dilation, as well as higher grayscale entropy and GLDS-CON, indicating that lower extremity exercise is associated with salutary changes in upper-extremity arterial wall structure and function. ClinicalTrials.gov Identifier: NCT01408901.