ADRB3 and hydrops fetalis: Note that commonly used β1–2AR‐blockers previously tested in RCT of HF (e.g. bisoprolol, metoprolol, and carvedilol) exhibit at least 100‐fold less affinity for β3AR and so would leave it unaffected.52 Finally, one can expect indirect cardiovascular benefits from activation of β3AR in extracardiac targets, such as beige/brown fat, with ensuing improvements in peripheral metabolism and insulin sensitivity, justifying our substudies on endothelial function, metabolic parameters, and brown fat activation by fluorodeoxyglucose–positron emission tomography.