Heart failure patients demonstrate impaired changes in brachial artery blood flow and shear rate pattern during moderate-intensity cycle exercise.

What is the central question of this study? We explored whether heart failure (HF) patients demonstrate different exercise-induced brachial artery shear rate patterns compared with control subjects. What is the main finding and its importance? Moderate-intensity cycle exercise in HF patients is associated with an attenuated increase in brachial artery anterograde and mean shear rate and skin temperature. Differences between HF patients and control subjects cannot be explained fully by differences in workload. HF patients demonstrate a less favourable shear rate pattern during cycle exercise compared with control subjects. Repeated elevations in shear rate (SR) in conduit arteries, which occur during exercise, represent a key stimulus to improve vascular function. We explored whether heart failure (HF) patients demonstrate distinct changes in SR in response to moderate-intensity cycle exercise compared with healthy control subjects. We examined brachial artery SR during 40 min of cycle exercise at a work rate equivalent to 65% peak oxygen uptake in 14 HF patients (65 ± 7 years old, 13 men and one woman) and 14 control subjects (61 ± 5 years old, 12 men and two women). Brachial artery diameter, SR and oscillatory shear index (OSI) were assessed using ultrasound at baseline and during exercise. The HF patients demonstrated an attenuated increase in mean and anterograde brachial artery SR during exercise compared with control subjects (time × group interaction, P = 0.003 and P < 0.001, respectively). Retrograde SR increased at the onset of exercise and remained increased throughout the exercise period in both groups (time × group interaction, P = 0.11). In control subjects, the immediate increase in OSI during exercise (time, P < 0.001) was normalized after 35 min of cycling. In contrast, the increase in OSI after the onset of exercise did not normalize in HF patients (time × group interaction, P = 0.029). Subgroup analysis of five HF patients and five control subjects with comparable workload (97 ± 13 versus 90 ± 22 W, P = 0.59) confirmed the presence of distinct changes in mean SR during exercise (time × group interaction, P = 0.030). Between-group differences in anterograde/retrograde SR or OSI did not reach statistical significance (time × group interactions, P > 0.05). In conclusion, HF patients demonstrate a less favourable SR pattern during cycle exercise than control subjects, characterized by an attenuated mean and anterograde SR and by increased OSI.