Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): MoH Research Grant "Development of methods for differentiated prevention and treatment of potentially dangerous heart rhythm disorders" Prediction of adverse outcomes in patients after myocardial infarction (MI) remains a serious and not completely resolved problem, which pushes researchers to search for new technologies. One of the relatively promising new non-invasive methods for predicting sudden coronary death in patients with coronary heart disease and ventricular arrhythmias (VA) may be an assessment of heart rate turbulence (HRT). Given its important prognostic role, primarily in patients after MI, the aim of this work was to study the relationship between HRT and cardiovascular remodeling in patients with VA with history of MI and multivessel nature of coronary lesions. Materials and research methods 123 patients with history of MI, aged 38 to 76 years (average age 61.0 ± 7.6 years), were included into the study. The multivessel nature of coronary lesions was established based on the results of diagnostic selective coronary angiography. All patients underwent Holter monitoring of the electrocardiogram (HMECG). HRT was determined using two indicators, in accordance with the guidelines: Turbulence Onset (To, %) and Turbulence Slope (Ts, ms/RRi). Results Potentially dangerous ventricular arrhythmias (PDVA) were noted in more than half of the examined patients (n = 67; 54.5%). In analyze of the structure of PDVA, II class of VA, as the highest class, was not observed in any of the examined patients, class III was detected in 35% of cases, IVA – in 37.5%, and IVB – in 27.5%. In assessing the frequency of VAs, according to the Bigger classification, frequent PVC >10 VA/hour was detected in 41.5% of patients. The analysis of the HRT indicators did not reveal a decrease in the mean values both To (-1.2 ± 1.5%) and Ts (3.9 ± 3.1 ms/RRi) indicators in the main group of patients. However, after appropriate separation of the main group, 21.1% of them had disorders of only one (category 1; 15.4%) or both of the HRT indicators (category 2; 5.7%). Category 0 included patients without any disorder of HRT indicators. In analysis of the relationship between the PDVA and the category of HRT reduction, a significant interrelation between them was revealed (Table 1). Result Our study demonstrates presence of strong interrelation between HRT parameters disorder and severity of PDVA. Thus, study of HRT in patients after MI could be a strong and independent predictor of cardiovascular events including sudden cardiac death. Abstract Figure. Tab. 1. Interrelation between HRT and VA

This work represents literature review data regarding the study of the effect of surgical myocardial revascularization on the processes of electrical myocardial instability underlying the onset of life-threatening ventricular arrhythmias, as well as the possibilities for its non-invasive assessment by studying the heart rhythm variability and turbulence. Analyzed data demonstrated that, relying only on the presence of a viable myocardium, it is often impossible to predict the positive effect of revascularization on the prognosis in patients, especially those with reduced myocardial contractility. Considering the well-studied relationship between myocardial remodeling and neurohormonal activation, such non-invasive methods for assessing vegetative regulation of cardiac activity, as heart rate variability and turbulence may provide additional diagnostic information. The literature data indicate that heart failure, ventricular arrhythmias and recurrences of angina and myocardial infarction are the main problems that determine an unfavorable outcome in the postoperative period. There is important evidence that violations of the vegetative regulation of the heart, the heterogeneity of repolarization processes in the myocardium are integral indicators of the morphofunctional changes occurring in the process of coronary heart disease (CHD) progression. The role of indicators of heart rate variability and turbulence as predictors of sudden cardiac death was proved, mainly due to fatal ventricular heart rhythm disorders and cardiovascular mortality. Along with this, changes in these indicators, and their prognostic role in patients with CHD in revascularization are the subject of discussion, which determines the relevance of further studies on the effect of various methods of revascularization on the electrical instability of the myocardium, as one of the most important factors in the development of life-threatening ventricular arrhythmias that are predictors of sudden cardiac death, especially in patients who previously had acute myocardial infarction. Besides it is important to study the effect of myocardial revascularization on the indicators of cardiac autonomic regulation and the possibility of their use as prognostic criteria before and after surgery.

No abstract