Left bundle-branch block: the relationship between electrocardiogram electrical activation and echocardiography...

Area of Science:

• Cardiology
• Medical Imaging
• Electrophysiology

Background:

• The relationship between ECG-based electrical activation and echocardiography-based mechanical contraction in left bundle-branch block (LBBB) is not well-defined.
• Recent independent publications introduced strict physiological criteria for LBBB diagnosis using both ECG and echocardiography.
• The study investigated the correlation between these two diagnostic modalities and their predictive value for cardiac resynchronization therapy (CRT) response.

Purpose of the Study:

• To establish the relationship between ECG and echocardiography findings in LBBB patients.
• To evaluate the utility of new strict criteria for LBBB detection using both modalities.
• To determine the association between LBBB diagnosis by these criteria and response to CRT.

Main Methods:

• Sixty-six LBBB patients underwent ECG and 2D strain echocardiography before CRT implantation.
• Strict ECG criteria included QRS duration, specific lead patterns (QS/rS), and mid-QRS notching.
• Echocardiographic criteria involved assessing contraction timing and wall motion abnormalities.

Main Results:

• ECG and echocardiography LBBB diagnoses were concordant in 84% of patients.
• Patients meeting strict ECG criteria for LBBB showed an 82% CRT response rate, compared to 21% in those without.
• Concordant LBBB diagnosis by both methods predicted a high CRT response rate (95%).

Conclusions:

• A strong correlation between ECG electrical activation and echocardiographic mechanical contraction in LBBB is demonstrated.
• These findings suggest that integrated ECG and echocardiography criteria can accurately identify LBBB.
• The study provides a potential method to better select patients who will benefit from CRT.