S100A8 and cardioembolic stroke: By categorizing stroke patients based on stroke etiology [large artery atherosclerosis, cardioembolism, and embolic stroke of undetermined source (ESUS)], we found that patients with cardioembolic stroke had significantly higher systemic plasma levels of S100A8/A9 compared to those with ESUS [median: 506 ng/ml (IQR: 353–868) vs. median: 398 ng/ml (IQR: 239–647), p = 0.02] (Fig. 2F).