The influence of recording technique on the normal atrial vectorcardiogram

P wave analysis in 2464 orthogonal electrocardiograms from normal subjects and patients with atrial overload

The purpose of this study was to establish limits of normal for P wave measurements, and to propose criteria for routine electrocardiographic readings and for multivariate analysis to recognize left atrial overload (LAO) and right atrial overload (RAO) in the orthogonal electrocardiogram (ECG). Frank ECG's were obtained from 2464 subjects, including 580 normals, 164 patients with mitral valve disease (MVD) forming the LAO group, and 623 with chronic lung disease (CLD) as the RAO sample. Each group was divided into training and test sets. Using a digital computer, 120 different P wave measurements were computed for each ECG to find optimal discriminators between normal (N), LAO, and RAO.

In the training set of MVD, using three scalar measurements, LAO was recognized in 57% with 3% false positives. These criteria diagnosed LAO in 70% of the test cases of MVD. Four discriminators identified RAO in 30% and 37% of training and test cases of CLD with 11% false positives.

A set of 15 measurements obtained by multivariate analysis was used in a classification in which the three groups, N, LAO, and RAO were considered simultaneously. Ninety-four percent N, 74% LAO, and 45% RAO in the training sets, and 95%, 71%, and 24% in N, LAO, and RAO test sets were correctly identified. An attempt was made to correlate the rate of recognition of LAO with the degree of LAO estimated by cardiac catheterization. Data reported in the present study can serve as standard for P wave analysis in the Frank ECG.