Computer Analysis of the Orthogonal Electrocardiogram and Vectorcardiogram in Mitral Stenosis

Abstract

Orthogonal electrocardiograms (Frank lead system) from 191 patients with pure mitral stenosis (MS) were compared to electrocardiograms from 510 normal patients and 296 patients with pulmonary emphysema (PE). All patients with MS underwent right heart catheterization; 121 patients underwent both left and right heart catheterization. Three hundred and thirty electrocardiographic measurements were obtained from each record and tested for their ability to distinguish mitral stenosis from normal. Two sets of diagnostic discriminators were selected: (1) ECG measurements which can be easily obtained by hand and (2) measurements which performed best in multivariate analysis using linear discriminant functions. The patients with mitral stenosis were separated into three hemodynamic subgroups according to mean pulmonary artery pressure (PAP) (0-30, 31-40, and >40 mm Hg). The ability of the selected measurements to recognize mitral stenosis increased as mean pulmonary artery pressure rose. The superiority of the multivariate technique, using nine measurements simultaneously, was readily demonstrated when compared to the hand measurements. At a constant level of 6% false positives, multivariate analysis allowed a 74% recognition rate of mitral stenosis compared to 44% with hand measurements. Additional Indexing Words: Digital computerMultivariate analysis Right ventricular hypertrophy THE SALIENT FEATURES of both the electrocardiogram (ECG) and vectorcardiogram (VCG) in patients with mitral stenosis have been previously described by a number of investigators.'1"0 In general, it is concluded that the usefulness of the ECG and VCG for the diagnosis and assessment of the severity of mitral stenosis remains modest. The cancellation of right ventricular forces by opposing left ventricular forces does not allow the ECG characteristics of right ventricular hypertrophy (RVH) to be manifest until the RVH is marked. This in part explains the lack of sensitivity of the standard ECG and VCG in detecting mild or moderate mitral stenosis (MS). It has been demonstrated previously that computer analysis of the From the Veterans Administration Cooperative Study on