Myocardial dyssynchrony and response to cardiac resynchronization therapy

The aim of the study was to provide comparative analysis of the zones with maximum intraventricular myocardial dyssynchrony (IVD) and the localizations of ventricular electrodes in patients with differential responses to cardiac resynchronization therapy (CRT). Materials and Methods: Retrospective study comprised patients (n=40) who had sinus rhythm, complete left bundle branch block (LBBB), left ventricular (LV) ejection fraction (EF) 15%, relative increase of LV eF ≥10%), and group 2 (n=20) with insufficient response to CRT (the absence of dynamics in the sizes, volumes, and LV EF). For topical evaluation of the zone of stimulation with ventricular electrode, a vector analysis of ECG was performed in the beginning and the end of the follow up period (VL was divided in 12 segments, RV was divided in 3 segments). Intraventricular and interventricular dyssynchrony of the myocardium was detected by echocardiography with tissue Doppler sonography. Results: initially, the groups did not differ in regard to gender, age, and parameters of echocardiography with tissue Doppler sonography. The absence of initial IVD was observed in 7 patients of group 1 and in 8 patients of group 2, p = 0.503, cardiomyopathy of ischemic genesis significantly prevailed in group 2 (75%, n=15, р=0.014). Dislocation of the leads was not documented for the entire period of the study, displacement of LV electrodes within the vein of the coronary sinus occurred in three cases. The final sizes, volumes, and LV EF values differed between the groups (р