Myocardial work and manifestation of cardiac dysfuction in patients with permament long-term stimulation of the right ventricle

Aim . To evaluate the relationship between mechanical dyssynchrony, defined as myocardial work components and manifestations of cardiac dysfunction in patients with permanent right ventricular pacing. Material and methods . The study included 55 patients (25 men, mean age 63±12 years) with implanted permanent pacemakers and left bundle branch block type paced QRS complex morphology and 20 healthy volunteers (15 men, mean age 32.4±7.4 years). The patients included in the study were examined twice: initially before pacemaker implantation and again at the time of study inclusion. A standard echocardiographic study was performed with an additional assessment of the degree of global longitudinal strain (GLS) and myocardial performance parameters - global constructive myocardial work (GCW), global wasted myocardial work (GWW), global work index (GWI) and global work efficiency (GWE) before and after pacemaker implantation. In all patients, segments with maximum and minimum GWI were determined. The parameters of myocardial function were analyzed depending on the localization of the pacemaker stimulating head, and a comparison was made with the parameters of myocardial function in 20 healthy volunteers. Results . In 18.2% of patients, against the background of right ventricular pacing, a decrease in left ventricular ejection fraction (LVEF) from normal values to 55 (53.5; 55.8) % was recorded, in 5 (50%) of them, signs of chronic heart failure functional class II-III were recorded. An increase in the degree of tricuspid regurgitation (TR) was found in 29.9% of patients. In patients against the background of long-term pacing, the GLS, GWI, GCW and GWE indicators were statistically significantly lower than in the group of healthy volunteers, and the GWW indicator was higher than the reference values of the control group. Patients with an apical-septal localization of the stimulating electrode head have statistically lower GWI and GCW values than patients with a more “basal” location of the electrode head in the middle third of the interventricular septum (1042.23±308.85 versus 1430±514 mmHg%, p = 0.049 and 1457 (1256; 1766) versus 2089 (1831; 2186) mmHg%, p = 0.04). Conclusion . The localization of the stimulating electrode head does not affect the development of negative dynamics of LVEF and TR, but has a significant effect on the myocardial performance indicators. In patients with the apical-septal localization of the electrode, the worst values of the constructive work of the myocardium were noted, and in patients with the localization of the stimulating electrode head in the right ventricular outflow tract area, the best indicators of the constructive work of the myocardium were noted.