Ventricular dysfunction consequences of mechanical dyssynchrony in isolated complete right bundle branch block versus...

Area of Science:

• Cardiology
• Cardiac Electrophysiology
• Echocardiography

Background:

• Isolated complete bundle branch block (ICBBB) without structural heart disease can be left (CLBBB) or right (CRBBB).
• CLBBB is linked to ventricular dysfunction due to dyssynchrony.
• CRBBB, once considered benign, is now associated with adverse cardiovascular outcomes.

Purpose of the Study:

• To evaluate cardiac mechanical synchrony and systolic/diastolic function in patients with isolated CRBBB.
• To compare cardiac synchrony and function in isolated CRBBB patients versus isolated CLBBB patients.

Main Methods:

• A cross-sectional study involving 44 isolated CRBBB patients, 44 isolated CLBBB patients, and 42 healthy controls.
• Transthoracic echocardiography was used to assess right ventricular (RV) and left ventricular (LV) mechanical dispersion, global longitudinal strain (GLS), and diastolic function (E/e').
• Statistical analyses included ANOVA, Pearson correlation, and linear regression.

Main Results:

• Isolated CRBBB patients showed significantly increased RV mechanical dispersion, decreased RV and LV GLS, and elevated E/e' compared to healthy controls.
• Compared to isolated CLBBB patients, isolated CRBBB patients had greater RV mechanical dispersion, elevated tricuspid valve E/e', and reduced RV GLS.
• RV mechanical dispersion was independently associated with RV GLS, while RV GLS and atrioventricular synchrony predicted LV GLS in CRBBB patients.

Conclusions:

• Patients with isolated CRBBB exhibit impaired cardiac mechanical synchrony and ventricular function, with more pronounced RV dysfunction than those with isolated CLBBB.
• Right intraventricular synchrony is an independent predictor of RV systolic dysfunction in isolated CRBBB.
• Atrioventricular synchrony and RV systolic function are independent predictors of LV systolic function, necessitating comprehensive echocardiographic assessment and monitoring for isolated CRBBB.