Heart Failure/diagnosis; Heart Failure/physiopathology; Quality of Life; Ventricular Dysfunction, Left/diagnosis; Ventricular Dysfunction, Left/physiopathology; Adrenergic beta-Antagonists/therapeutic use; Aged; Aged, 80 and over; Angiotensin-Converting Enzyme Inhibitors/therapeutic use; Blood Flow Velocity/drug effects; Blood Flow Velocity/physiology; Diastole/drug effects; Diastole/physiology; Echocardiography, Doppler; Female; Follow-Up Studies; Heart Failure/drug therapy; Heart Failure/epidemiology; Humans; Italy; Length of Stay; Male; Middle Aged; Mitral Valve Insufficiency/diagnosis; Mitral Valve Insufficiency/epidemiology; Mitral Valve Insufficiency/physiopathology; Patient Readmission; Prevalence; Prognosis; Prospective Studies; Severity of Illness Index; Stroke Volume/drug effects; Stroke Volume/physiology; Survival Analysis; Systole/drug effects; Systole/physiology; Treatment Outcome; Ventricular Dysfunction, Left/drug therapy; Ventricular Dysfunction, Left/epidemiology