The results of examination of 61 patients suffering from ischemic heart disease are analysed. All were subjected to catheterization of the right and left parts of the heart, left ventriculography, and selective coronarography. Some parameters of intracardiac hemodynamics, including the end diastolic pressure in the left ventricle, were determined. Atrial vectorcardiogram was recorded after I. T. Akulinichev's system (with mV = 100 mm). Comparison of the parameters of the atrial P loop of the vectorcardiogram with the findings of heart catheterization showed a direct dependence between the atrial changes recorded on the vectorcardiogram and the value of the left ventricular end diastolic pressure. Signs of overexertion of the left atrium grow with an increase in the end diastolic pressure. Quantitative dependence between these parameters is demonstrated. When the end diastolic pressure grows higher, overexertion of the left atrium is naturally joined by overexertion of the right atrium. Atrial vectorcardiography may be an important invasive method for appraising the functional condition of the left ventricular myocardium in patients with ischemic heart disease.