Echocardiographic evaluation of ventricular dyssynchrony in patients with left bundle branch block

Area of Science:

• Cardiology
• Cardiac Electrophysiology
• Diagnostic Imaging

Background:

• Left bundle branch block (LBBB) can lead to cardiac dyssynchrony, impacting left ventricular (LV) systolic function.
• The relationship between reduced ejection fraction (EF) and the severity of dyssynchrony in LBBB patients requires further investigation.

Purpose of the Study:

• To compare the degree of cardiac dyssynchrony in patients with LBBB and low EF versus those with LBBB and normal LV systolic function.
• To evaluate the utility of Tissue Doppler Imaging (TDI) in quantifying dyssynchrony in LBBB.

Main Methods:

• 38 patients with LBBB and low EF (<50%) and 31 with LBBB and normal EF (>=50%) underwent Doppler echocardiography, ECG, and TDI.
• Precontraction time (PCTm) was measured in myocardial segments to assess intraventricular and interventricular dyssynchrony.
• Interventricular activation delay was calculated by comparing the most delayed LV segment to the right ventricular (RV) lateral wall.

Main Results:

• Patients with low EF exhibited significantly increased intraventricular (p=0.03) and interventricular dyssynchrony (p=0.006) compared to normal EF.
• The LV basal lateral segment showed significant delays in the low EF group.
• Overall PCTm was greater in the low EF group, indicating more pronounced systolic activation delays.

Conclusions:

• All patients with LBBB demonstrate some cardiac dyssynchrony, with significantly greater dyssynchrony observed in those with lower ejection fraction.
• TDI is a valuable non-invasive tool for assessing the severity of regional activation delays in ventricular walls among LBBB patients.