Reassessment of electrovectorcardiographic signs of left atrial enlargement.

Echocardiographic left atrial size was correlated with 27 electrovectorcardiographic parameters in 93 subjects. In 20 of them hemodynamic studies, including calculation of the left atrial volume, were performed. Subjects were divided into four groups as follows: Group I, 21 healthy subjects; group II, 45 patients with heart disease but no left atrial enlargement; group III, 15 patients with heart disease and left atrial size from 4.1 to 5 cm; and group IV, 12 patients with heart disease and a left atrial size exceeding 5 cm. A good correlation was found between left atrial size and the following parameters: Duration of P wave in standard lead II, voltage of both terminal forces of P wave in lead V1 and its maximal vector in the frontal and sagittal planes. A new index (duration/voltage of P wave in lead II) was postulated, which showed an excellent correlation with left atrial size (p less than 0.001). In all cases the superposition between groups was excessive. These findings indicate the limitations of the classical patterns and raise interest in new parameters concerning the electrocardiographic diagnosis of left atrial enlargement.