Furthermore QRS complex reduction led to increase in LV ejection fraction (r = 0.47, p = 0.001) and to reduction of LV end-systolic volume (r = 0.42, p = 0.004).  The presence of complete left bundle branch block before CRT implantation is associated with a better response to CRT compared to other myocardial intraventricular conduction disturbances. 
THERM