Autonomic dysregulation in HFrEF plays a major role in endothelial dysfuction. Low level Tragus stimulation (LLTS) is a novel, non-invasive method of autonomic modulation.
We enrolled 50 HFrEF patients (LVEF≤40%) in a randomized, double-blinded, crossover study. Day 1: patients underwent 60 minutes of LLTS with a transcutaneous stimulator (20Hz, 200 μs pulse width) or sham (ear lobule) stimulation. Macrovascular function was assessed using flow mediated dilatation (FMD) in brachial artery and cutaneous microcirculation with laser speckle contrast imaging in hand and nail bed. Day 2: patients were crossed over to other study arm and underwent sham or LLTS; vascular tests were repeated pre- and post-stimulation.
Compared to sham, LLTS improved FMD by increasing the %-change in brachial artery diameter (5 to 7.5, LLTS on day 1, p=0.02; 4.9 to 7.1, LLTS on day 2, p= 0.003), compared to no significant change in the sham group (4.6 to 4.7, p=0.84 on day 1 and 5.6 to 5.9, p=0.65 on day 2). Cutaneous microcirculation in hand showed no improvement and perfusion of nail bed showed a trend towards improvement.
Our study demonstrated beneficial effects of acute neuromodulation on macrovascular function. Larger studies to validate these findings and understand mechanistic links are warranted.

Copyright © 2020. Published by Elsevier Inc.