Electromechanical correlations in hypertrophic subaortic stenosis.

Six of 14 patients with hemodynamically proven subaortic stenosis (SAS) showed electrocardiographic patterns consistent with myocardial infarction. Analysis of the 0.02-sec horizontal plane vector allowed discrimination between true myocardial infarction and SAS. In SAS this vector was shifted anteriorly and to the right consistent with septal hypertrophy and increased left-to-right early septal forces. Cineangiographic studies of left ventricular contraction revealed a unique pattern also consistent with septal hypertrophy disproportionately greater than that of the ventricular free wall. No correlation existed between maximal instantaneous vectorial voltage, and either the peak left ventricular pressure or the pressure gradient within the left ventricular outflow tract. Striking increases in vectorial forces in SAS may be related to dystrophic changes within the myocardial mass and may not be attributable to simple hypertrophy secondary to hemodynamic obstruction.