Septal deformation patterns delineate mechanical dyssynchrony and regional differences in contractility: analysis of...

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Imaging

Background:

• Cardiac resynchronization therapy (CRT) response is influenced by cardiac dyssynchrony and regional contractility.
• Septal deformation patterns may integrate information on dyssynchrony and contractility to predict CRT response.

Purpose of the Study:

• To investigate if septal deformation patterns can predict CRT response in patients with left bundle branch block (LBBB).
• To understand the relationship between septal deformation, dyssynchrony, and contractility using a computational model.

Main Methods:

• Assessed longitudinal septal strain using speckle tracking echocardiography in 132 CRT candidates with LBBB.
• Utilized the CircAdapt computer model to simulate dyssynchrony and varying contractility effects on septal deformation.
• Classified patients into three septal deformation patterns (LBBB-1, LBBB-2, LBBB-3).

Main Results:

• Identified three distinct septal deformation patterns: LBBB-1 (double-peaked systolic shortening), LBBB-2 (early shortening, late stretching), and LBBB-3 (pseudonormal shortening).
• LBBB-3 pattern was associated with more myocardial scar.
• The computer model demonstrated that LBBB-1 arises from activation time differences, while LBBB-2 and LBBB-3 result from superimposed hypocontractility.
• CRT response (improved ejection fraction, reduced ventricular volumes) was best in LBBB-1 and worst in LBBB-3 patients.

Conclusions:

• A double-peaked septal deformation pattern is characteristic of LBBB-induced dyssynchrony.
• Abnormal myocardial contractility alters this pattern, providing further prognostic information.
• Computational modeling aids in understanding septal deformation and predicting CRT outcomes.