PSMB3 and hydrops fetalis: Based on all the pre-clinical evidence discussed above, two clinical trials, the “Beta 3 Agonist Treatment in Heart Failure” (Beat-HF; clinicaltrials.gov: NCT01876433) and the “Assessment of Efficacy of Mirabegron, a New Beta 3-Adrenergic Receptor in the Prevention of Heart Failure” (Beta3_LVH; clinicaltrials.gov: NCT02599480), are evaluating the effects of β3-AR agonism on HF progression and development (commented on in [8]).