For each patient, standard resting 12-lead ECGs were recorded in the supine position (with simultaneous 3-lead acquisition) with a Cardimax ECAPS 12 2000 Compliant Electrocardiograph (Nihon-Kohden Co, Tokyo, Japan). Electrocardiographic abnormalities were classified according to standard criteria for conduction disturbances (intraventricular and atrioventricular), chamber overload, and abnormal Q waves [11]. The electrocardiographic variables assessed is sinus rhythm were: maximum P-wave duration and PR interval (typically in lead II), QRS complex duration (the longest ventricular duration in precordial leads), maximal absolute QRS complex in any precordial lead, presence of bundle branch block and/or left fascicular-block, presence of abnormal Q waves (Q-wave, defined as the first QRS deflection >1-mm deep and >0.04-ms wide), and left atrial overload (P-wave duration in lead II >110 ms or Morris index in V1 >4 millivolt.ms). In antero-septal leads (V1, V2 and V3) and in inferior leads (L2, L3 and aVF) the presence of Q-wave in two out of three leads was considered abnormal. An independent observer blind to the study analyzed the electrocardiographic records that were automatically obtained from electrocardiograph equipment. Subsequent 12-lead resting ECGs were recorded at each clinical visit in order to assess cardiac rhythm during follow-up. Plain chest roentgenogram was carried out on the same day and cardiomegaly was defined by a cardiothoracic ratio of more than 0.50.