Noninvasive and invasive evaluation of left bundle branch block (LBBB)

Area of Science:

• Cardiology
• Electrophysiology
• Diagnostic Imaging

Background:

• Left bundle branch block (LBBB) is a significant electrocardiographic finding with various underlying etiologies.
• Understanding the causes and diagnostic markers of LBBB is crucial for patient management.

Purpose of the Study:

• To investigate the common etiologies of LBBB.
• To identify electrocardiographic (ECG) and echocardiographic predictors of coronary artery disease (CAD) in LBBB patients.
• To assess the prevalence and significance of conduction delays in LBBB.

Main Methods:

• Nineteen patients with LBBB underwent comprehensive clinical, ECG, echocardiographic, electrophysiological, and coronary angiographic examinations.
• Analysis of ECG for specific wave morphologies (Q waves, T waves) and QRS axis.
• Echocardiography and left ventriculography to assess wall motion abnormalities.
• Electrophysiological studies to evaluate conduction intervals (PR, HV).

Main Results:

• Idiopathic/degenerative causes (52.6%) were most common, followed by atherosclerotic CAD (31.5%).
• Significant left anterior descending artery lesions were present in all CAD patients.
• ECG Q waves in leads I, aVL, V5, or V6 were most predictive of CAD; T-wave changes and QRS axis were not.
• Conduction delays, particularly infrahisian block, were frequent, often associated with prolonged PR or wide QRS durations.

Conclusions:

• Coronary artery disease is a significant cause of LBBB, often involving the left anterior descending artery.
• Specific ECG findings can aid in predicting CAD in LBBB patients.
• Electrophysiological evaluation is essential to identify conduction system disease in LBBB, guiding appropriate hemodynamic and angiographic assessment.