Dynamics of Non-Invasive Risk Factors of Sudden Cardiac Death after Myocardial Revascularization

Abstract

Background: An attempt was made to study the effect of surgical myocardial revascularization on the processes of electrical myocardium instability underlying the occurrence of life-threatening ventricular arrhythmias, as well as the possibility of its non-invasive assessment by studying heart rate variability (HRV) and heart rate turbulence (HRT), as well as the duration and dispersion of the QT interval. Based only on the presence of viable myocardium, it is often impossible to predict the positive impact of revascularization on a patient’s prognosis, especially with reduced myocardial contractility. Moreover, given the well-studied relationship between myocardial remodeling and neurohormonal activation, non-invasive methods for assessing the autonomic regulation of cardiac activity can provide additional diagnostic information. Along with this, changes in these indicators and their prognostic role in patients with coronary artery disease after revascularization are subjects of discussion. Methods and Results: All patients underwent a comprehensive clinical and biochemical blood test, transthoracic echocardiography, tissue Doppler echocardiography, ultrasound examination of brachiocephalic arteries, selective coronary angio- and ventriculography, as well as Holter monitoring. Results show that a year after the coronary intervention, there was a significant positive trend in the frequency and structure of ventricular arrhythmias (VA). HRV indicators generally did not show significant dynamics. Only an increase in the values of the SDANN and low-frequency power (LFP) indices was noted, indicating a gradual increase in the activity of the sympathetic part of the autonomic nervous system. HRT indicators also did not show significant dynamics. A significant increase was found in the number of patients with no signs of impaired HRT. The average duration of the QT interval decreased significantly. There was also a tendency to shorten the corrected QT interval; however, it was insignificant. In terms of dispersion, both the QT interval and its corrected index, no significant dynamics were recorded in the general group of patients. Conclusion: Our study found that in patients with prior myocardial infarction, after revascularization, significant positive dynamics were recorded in life-threatening ventricular arrhythmias, but were unreliable for the indicators of autonomic regulation of cardiac activity, such as HRV and HRT.