Background and Objective: One-third of heart failure cases also represent conduction disorders, such as Left Bundle Branch Block (LBBB), which leads to mechanical defects and ventricular dyssynchrony. This study aims to investigate the correlation between the degree of LBBB and other electrocardiographic parameters, along with the severity of ventricular dysfunction and mitral regurgitation (MR).
Methods: In this cross-sectional study, 40 patients (20 women/20 men) with non-ischemic LBBB were selected by continuous sampling from the patients of Fatemeh Zahra Sari Hospital in 2019. Electrocardiography (including QRS duration, R voltage of organ leads, S voltage in precordial leads, Cornell index, Sokolow-Lyon index, QRS axis deviation and Notched QRS in lateral leads), echocardiography (including Left Ventricular Ejection Fraction (LVEF)) and MR degree) and Tissue Doppler Imaging were investigated in selected patients.
Findings: The mean age of the patients was 64±13.5 years. 77.5% had LVEF less than 35%, 57.5% had intraventricular dyssynchrony>60 and 60% had interventricular dyssynchrony>40. There was a significant correlation between the level of LVEF (r=-0.464, p=0.003) and MR severity (r=0.332, p=0.037) and the severity of intraventricular dyssynchrony. In addition, septal to lateral wall motion delay in patients with LVEF less than 35% was significantly related to the level of intraventricular dyssynchrony (r=0.6712, p=0.000). Among the ECG parameters in patients with LVEF less than 35%, there was only a significant relationship between the maximum R range and the degree of interventricular dyssynchrony (r=0.438, p=0.014).
Conclusion: Our results indicated that LVEF and MR were correlated with the degree of ventricular dyssynchrony and they could be considered as valuable markers for LBBB. Septum to lateral wall delay, and septum to posterior, were also correlated.