Mechanical dyssynchrony evaluated by tissue Doppler cross-correlation analysis is associated with long-term survival...

Area of Science:

• Cardiology
• Medical Imaging
• Biomedical Engineering

Background:

• Mechanical dyssynchrony is a key factor in heart failure patients considered for cardiac resynchronization therapy (CRT).
• Accurate pre-implant assessment of dyssynchrony is crucial for optimizing CRT outcomes.
• Existing tissue Doppler imaging (TDI) indices have limitations in predicting long-term survival.

Purpose of the Study:

• To evaluate the association of longitudinal mechanical dyssynchrony, assessed by cross-correlation analysis (XCA), with long-term survival in CRT candidates.
• To compare the predictive performance of XCA-derived maximal activation delay (AD-max) against other TDI-derived indices.

Main Methods:

• 131 patients referred for CRT underwent assessment of mechanical dyssynchrony using TDI velocity curves.
• Maximal activation delay (AD-max) was calculated via XCA of TDI-derived myocardial acceleration curves.
• Other indices included time-to-peak opposing wall delay (OWD) and Yu index. Long-term outcomes (mortality, transplantation, LVAD) were modeled using Cox regression.

Main Results:

• AD-max was independently associated with improved survival (HR 0.35, P=0.01), even after adjusting for QRS duration and etiology.
• AD-max demonstrated significantly better predictive performance compared to Yu index, OWD, and left bundle branch block presence (P < 0.05).
• Patients without dyssynchrony but with QRS duration between 120-150 ms showed a particularly poor prognosis (HR 4.3, P < 0.01).

Conclusions:

• Mechanical dyssynchrony assessed by AD-max using XCA is a valuable predictor of long-term survival post-CRT.
• XCA-derived AD-max is superior to other TDI-based methods for patient selection in CRT.
• Identifying patients without dyssynchrony within the intermediate QRS duration group is critical for prognosis.