[Diagnosis of delayed upper left ventricular activation: limits of electrocardiography and usefulness of vectorcardiography].

The electrocardiographic (ECG) diagnosis of delayed ventricular left superior activation (DVLSA) is often difficult and uncertain, even when all the criteria proposed in clinical literature are fulfilled. The vectorcardiography (VCG) always permits an accurate diagnostic evaluation because the contour of the QRS loop describes successively the various phases of ventricular depolarization. Sensitivity and specificity of ECG in diagnosing DVLSA have been calculated referring to VCG analysis. The QRS loop initial forces orientation in the frontal plane, a VCG highly reliable criterion, was considered especially significant for this purpose. The sensitivity and specificity of ECG were, respectively, 75% and 95%. Moreover, this study has confirmed the low performance of frontal plane QRS axis criterion and the necessity of polyparametric method for a correct ECG-VCG diagnosis of DVLSA. However, the VCG is more reliable than ECG in such diagnosis because it allows thoroughly to analyze QRS-loop initial forces.