Denysiak et al. proved that soluble interleukin 1 receptor-like 1 (ST2) is a marker of advanced functional remodeling in patients with AF, and is associated with significantly longer ablation procedures independent of LA size [44], while other authors reported that increased LA volumes are correlated with higher serum ST2, marked fibrosis and poor outcome in patients with HF [45]. Here, IL1RL1 is linked to hydrops fetalis.