ADRB2 and Arrhythmia: Indeed, up to date, the FDA has approved 19 β-blockers as therapeutic agents to different diseases: β2-AR agonist salbutamol and formoterol for asthma and chronic obstructive airway disease, β1-AR antagonist metoprolol and bisoprolol for coronary heart disease and arrhythmias, β1-AR agonists such as dobutamine for acute heart failure, β1-/β2-AR antagonist carvedilol for chronic heart failure, β3-AR agonist mirabegron for overactive bladder syndrome, and many others [23].