IMPACT OF COVID-19 ON MICROCIRCULATION AND HEART RATE VARIABILITY IN PATIENTS WITH CHRONIC CORONARY ARTERY DISEASE

Abstract

COVID-19 is associated with a wide range of negative effects on the cardiovascular system. The aim of our study was to investigate the impact of COVID-19 on the interdependence of changes in the microcirculation system and heart rate variability in patients with chronic coronary artery disease (CAD). An ECG study was performed in 12-lead leads, as well as 24-hour Holter ECG monitoring and laser Doppler flowmetry (LDF). Patients were divided into 3 groups. Group 1 included patients with coronary artery disease (n = 32), group 2 - with coronary artery disease in combination with COVID-19 (n = 35), and group 3 - with COVID-19 (n = 35). The control group consisted of 30 conditionally healthy individuals. All subjects were determined: microcirculation index, capillary blood flow reserve of the occlusion test, as well as nitroglycerin test and wavelet transform indicators (the relationship between the frequency and amplitude of microcirculatory oscillations, which are divided into endothelial, neurogenic, myogenic, respiratory and cardiac mechanisms of microcirculation regulation). The deterioration of endothelial function, as measured by the maximum amplitude of endothelial flux motions, should be noted, and a decrease in the endotheliumdependent and endothelium-independent components of microcirculation regulation. The capillary blood flow reserve of the occlusion test in patients with CAD in combination with COVID-19 was lower than in patients with CAD (group 1) and COVID-19 (group 3). In patients of the study groups, the total heart rate variability decreased, parasympathetic activity was weakened, and the QT interval duration and its variability increased compared with controls. These changes were most pronounced in patients with coronary artery disease in combination with COVID-19 in terms of the standard deviation of all intervals, the parasympathetic component of regulation, and both characteristics of the QT interval. Thus, patients with chronic CAD and concomitant COVID-19, along with endothelial dysfunction and worsening venous outflow, showed signs of autonomic dysregulation and increased QT interval duration and variability. Additional consideration of the characteristics of the microcirculatory bed, heart rate variability and QT interval is advisable in the examination system of such patients.