Autonomic nervous system assessment by pupillary response as a potential biomarker for cardiovascular risk: A pilot study

Background: Cardiovascular risk (CVR) biomarkers are of increasing interest because of their potential utility in management of cardiovascular diseases. The activity of the autonomic nervous system (ANS) is known to be highly correlated with CVR and therefore, is a putative biomarker. Common ANS measurement tools have several technological limitations and high-variance signals. The pupillary responses (PR) is controlled by both components of the ANS, and recent advances in pupillometry are making this measurement, easy and reliable. Thus, PR assessment could become a useful clinical tool to measure the ANS modulation and its relation to CVR. Here, we aimed to evaluate differences in PR between low CVR and moderate/high CVR individuals. Methods: We performed a cross-sectional study. We recruited voluntaries with low CVR (group 1, n = 12) and patients with moderate/high CVR (group 2, n = 7). An eye tracker was used to measure PR to different visual stimulus that included colors (white, black, gray) and images with known emotional valence (pleasant, unpleasant and neutrals), which were intercalated by pink noise images. Differences in PR between both CVR groups were assessed by Mann Whitney U test of different epochs of the PR. Results: PR was significantly different between both CVR groups (p-value < 0,05) when the observed images were unpleasant, neutral, and pink noise, for different epochs of the PR. Conclusions: This is the first study that demonstrates that PR is different according to CVR. Thus, PR could be considered as a novel biomarker of CVR to be tested in prospective studies. (C) 2018 Elsevier Ltd. All rights reserved.