The association of glycemia level and myocardial functional indices in patients with coronary heart disease and type 2 diabetes mellitus

Abstract

Introduction. The strict control of glycemia does not always lead to positive effects associated with a decrease in cardiovascular complications. Moreover, the combined development of type 2 diabetes mellitus (T2DM) and coronary heart disease (CHD) makes it challenging to control glycemic levels adequately. Objective. To study the relationship between glycemia and functional myocardial parameters in patients with coronary artery disease and type 2 diabetes mellitus. Material and Methods. The study included patients with a diagnosis of chronic coronary artery disease associated with type 2 diabetes mellitus. We studied the echocardiography-based structural and functional parameters of the heart and the contractile properties of the myocardium in patients ex vivo depending on the level of glycated hemoglobin (НbА1с). The ex vivo studies were performed on trabeculae isolated from the right atrial appendage obtained during coronary artery bypass surgery. The contractile function of trabeculae was assessed based on an extrasystolic effect and a resting effect (post-rest reaction). Results. Patients were divided into two groups according to the HbA1c level: group 1 included patients with HbA1c less than 8%; group 2 comprised patients with HbA1c more than 8%. The main clinical baseline parameters were similar between the groups. The ejection fraction (EF) was higher, whereas the thickness of the left ventricular posterior wall (LVPW) was lower in patients of group 1 compared to the corresponding parameters of group 2. The ex vivo study of myocardial contractility showed that extrasystolic contractions occurred at earlier extrasystolic intervals in patients of group 2, suggesting higher excitability of the cardiomyocyte membranes. At the same time, post-extrasystolic contractions of trabeculae in patients of group 2 had significant potentiation. The amplitude of post-rest trabeculae contractions was potentiated at short rest periods in patients of both groups. However, post-rest contractions significantly increased with an increase in the duration of rest periods only in group 2. Post-rest inotropic response in patients of group 1 did not have any potentiation after long rest periods. Conclusions. The results of this study based on the contractility of isolated trabeculae showed that the increased HbA1c levels are better indicators of the myocardial functional state.