Rationale and Design of a Multicentre, Randomized, Placebo-Controlled Trial of Mirabegron, a Beta3-Adrenergic Receptor Agonist on Left Ventricular Mass and Diastolic Function in Patients with Structural Heart Disease Beta3-Left Ventricular Hypertrophy (Beta3-Lvh) (Vol 5, Pg 830, 2018)