Study population
We prospectively screened 139 consecutive outpatients with non-ischaemic DCM who were referred to our echocardiography department. DCM was defined using the following criteria: (1) end-diastolic left ventricular (LV) volume index > 74 ml/m2 in males and > 61 ml/m2 in females, according to cut-offs from the current guidelines of chamber quantification [14] and (2) LV ejection fraction (EF) <40% by two-dimensional (2D) Simpson biplane method. We excluded patients with atrial fibrillation (15 patients), poor acoustic window or inability to hold breath (10 patients), conduction disturbances (3 patients) and cor pulmonale (6 patients), leaving a final study population of 105 patients. Included patients were clinically stable (i.e., with no change in diuretic dose for at least 2 weeks prior to enrollment).
Three investigators collected basic demographic and clinical data. Patients’ clinical status was assessed by a physician using the New York Heart Association (NYHA) classification. Severe symptoms of HF were defined by NYHA class III or IV. BNP serum levels were available in 62 patients. Informed consent was obtained from all patients and the study protocol was approved by the local human research committee.