Dyssynchrony, contractile function, and response to cardiac resynchronization therapy.

Area of Science:

• Cardiology
• Medical Imaging
• Heart Failure Management

Background:

• Cardiac resynchronization therapy (CRT) improves outcomes in heart failure, but about 30% of patients do not respond fully.
• Identifying non-responders is crucial for optimizing treatment strategies.

Purpose of the Study:

• To investigate if combined assessment of left ventricular (LV) dyssynchrony and contractile function using strain-based imaging can predict CRT benefit.
• To identify patient subgroups most likely to benefit from CRT.

Main Methods:

• 1077 patients with heart failure (NYHA class I/II, LVEF ≤30%, QRS width ≥130 ms) from the MADIT-CRT trial were analyzed.
• Echocardiographic assessments included LV dyssynchrony (standard deviation of time-to-peak transverse strain) and global longitudinal strain (GLS).
• Treatment effect on death or heart failure events was evaluated based on baseline imaging parameters.

Main Results:

• The greatest benefit from CRT was observed in patients with mild to moderate dyssynchrony (142-230 ms) and better baseline contractile function (GLS ≤-8.7%).
• Patients with both mild/moderate dyssynchrony and best contractile function showed the largest CRT benefit (aHR 0.20).
• Dyssynchrony and GLS independently predicted CRT response, even when accounting for QRS width, LVEF, and left bundle-branch block.

Conclusions:

• Both mechanical dyssynchrony and myocardial contractile function are significant independent predictors of CRT response.
• Strain-based imaging parameters can refine patient selection for CRT.