Agra-Bermejo et al. suggested that isoproterenol treatment of patients with HF or atrial fibrillation significantly increased CD5L secretion from epicardial adipose tissue, which may activate the toll-like receptor 4/nuclear factor-kappa B (NF-κB) signaling pathway and produce pro-inflammatory cytokines (Agra-Bermejo et al., 2020). Here, TLR4 is linked to hydrops fetalis.