Echocardiographic parameters at baseline (black outlined bars), after 28-day exposure to saline or isoproterenol infusion (HF-28d, blue outlined bars) and at 56 days after exposure + recovery period (REC-56d, red outlined bars) in young and elderly mice. LVDd: End-diastolic left ventricular diameter; LVDs: End-systolic left ventricular diameter; IVS: interventricular septum thickness; PW: posterior wall thickness; EF: ejection fraction; FS: fractional shortening). N = 6/7 in sham/ISO-treated young mice; N = 3/4 in sham/ISO-treated elderly mice. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001.