The aim of the study was to evaluate the volume fraction of interstitial myocardial collagen in patients with stable angina pectoris depending on the state of the coronary bed and to analyze the relationship with the index of global longitudinal deformation of the left ventricle. The medical examination included 63 men with coronary artery disease: stable angina pectoris and preserved systolic function of the left ventricle (left ventricular ejection fraction greater than 50 % (Simpson's method)). At the time of the study, all patients had a sinus rhythm of the heart. Coronary angiography was performed according to the standard procedure. The index of global longitudinal deformation of the left ventricle was evaluated using speckle tracking technology in echocardiography. Based on the left ventricular myocardial mass index, the total voltage of QRS complexes in twelve standard electrocardiography leads, and the patient's height index, the volume fraction of interstitial collagen of the left ventricular myocardium was calculated. It was found that in patients with coronary artery disease: stable angina pectoris and preserved systolic function of the left ventricle, the degree of interstitial fibrosis of the left ventricle, estimated by the volume fraction of interstitial myocardial collagen, depends on the degree of coronary artery stenosis. In the group of patients with moderate atherosclerotic coronary artery disease (stenosis 21–70 %), a direct statistically significant moderate correlation between these indicators was established (r = 0.56, p = 0.039), while in the group of patients with severe coronary artery disease (stenosis ≥71 %), an even closer statistically significant correlation was revealed (r = 0.63, p = 0.031). With the progression of the atherosclerotic process in the coronary arteries, the degree of fibrosis of the left ventricular myocardium increases, which is associated with increased impairment of the global longitudinal systolic deformation of the left ventricle.