Impact of Left Bundle Branch Block on Left Atrial Dyssynchrony and Its Relationship to Left Ventricular Diastolic Function in Patients with Heart Failure and Dilated Cardiomyopathy

Background and Objectives:The impact of left bundle branch block (LBBB) on left atrial (LA) dyssynchrony in heart failure (HF) patients with non-ischemic dilated cardiomyopathy (DCM) has not been clearly elucidated.Methods: Eighty consecutive symptomatic HF patients with non-ischemic DCM (left ventricular ejection fraction, LVEF<35%) were included.LBBB was defined on electrocardiography.Left ventricular (LV) systolic and diastolic dyssynchrony index and LA dyssynchrony index were obtained by color-coded tissue Doppler imaging.Results: There was no significant difference in LV size, LVEF, LV global longitudinal strain, peak atrial longitudinal strain and LA volume between patients with LBBB (n=38) and no LBBB (n=42).There was a significant difference in LV systolic dyssynchrony index (p=0.014)and there was a mild difference in LV diastolic synchronicity index (p=0.045)between patients with LBBB and no LBBB.However, there was no difference in LA dyssynchrony index between the 2 groups (p=0.60).LA dyssynchrony index was not related to LV systolic and diastolic dyssynchrony indexes, but it was related to the deceleration time of mitral early diastolic velocity (E), the ratio of E to mitral annular early diastolic velocity (E/e′) and LA volume.E/e′ was most related to LA dyssynchrony index (r 2 =0.325, p=0.002).Conclusions: LBBB influences both LV systolic and diastolic dyssynchrony, but not LA dyssynchrony.LA dyssynchrony was related to LV diastolic function regardless of the presence of LBBB in in patients with non-ischemic DCM.