[Comparison between vectocardiogram and echocardiogram in the diagnosis of left atrial enlargement (author's transl)].

The purpose of this study was to evaluate the influence of atrial enlargement on P wave abnormalities in "primary" (mitral stenosis) and "secondary" (left ventricular involvement) forms of left atrial overload. Echocardiograms and Frank Vectorcardiograms were obtained from 42 subjects, including 12 patients with mitral stenosis (group I A), 4 with mitral insufficiency (group I B), and 26 with left ventricular disease. Good correlations were founded between left atrial dimension and the following vectorcardiographic criteria: magnitude of the positive P vector in lead Z, sum of the positive P wave in leads X and Z, P positive duration/PR segment ratio in lead Z. No specific difference has been found in the vectorcardiographic abnormalities of the "primary" and "secondary" left atrial enlargement. Separate analysis revealed that P wave duration or amplitude changes can be proposed in group I A as specific and sensible criteria of left atrial enlargement. In contrast, the same criteria are highly unspecific when applied to the patients with left ventricular disease, because they can reflect the influence of other variables (left atrial pressure, intra-atrial conduction defects). Comparison of our results with those of other studies of P wave analysis did not demonstrate the superiority of the vectorcardiogram over the conventional electrocardiogram in the diagnosis of left atrial enlargement.