In an exploratory analysis, the mean LVEF in patients with more severe HF at baseline (LVEF less than 40%) was increased in patients who received mirabegron compared with those given placebo (mean difference, +5.5%; p < 0.03) [143], suggesting that the activation of Na+-K+ ATPase induced by β3-AR agonist could be more effective in the treatment of advanced stages of HF. Here, ADRB3 is linked to hydrops fetalis.