Has mechanical dyssynchrony still a role in predicting cardiac resynchronization therapy response?

Area of Science:

• Cardiology
• Echocardiography
• Heart Failure Management

Background:

• Current cardiac resynchronization therapy (CRT) guidelines primarily focus on electrical dyssynchrony (QRS duration).
• Mechanical dyssynchrony assessment using tissue Doppler imaging (TDI) is not routinely incorporated.
• Predicting CRT response remains a challenge, necessitating improved patient selection criteria.

Purpose of the Study:

• To evaluate the impact of isolated and combined electrical and mechanical dyssynchrony on CRT reverse remodeling.
• To compare CRT response rates across different dyssynchrony groups.
• To determine if combining electrical and mechanical dyssynchrony assessment enhances CRT efficacy.

Main Methods:

• One hundred ninety-two CRT patients underwent echocardiography before and after CRT.
• Patients were categorized into isolated electrical dyssynchrony (QRS ≥ 120 ms, TS-SD < 32.6 ms), isolated mechanical dyssynchrony (QRS < 120 ms, TS-SD ≥ 32.6 ms), or combined dyssynchrony (QRS ≥ 120 ms, TS-SD ≥ 32.6 ms).
• CRT response was defined as ≥15% reduction in left ventricular end-systolic volume (LVESV) at 6-month follow-up.

Main Results:

• Overall, 45% of patients responded to CRT.
• The highest response rate (52%) was observed in patients with combined electrical and mechanical dyssynchrony (Group 3).
• Patients with isolated electrical dyssynchrony (Group 1) showed no significant improvement in cardiac volumes or function, while Group 2 (isolated mechanical) showed some improvement.

Conclusions:

• Combining electrical (QRS duration) and mechanical (TDI-derived TS-SD) dyssynchrony assessment significantly improves prediction of CRT response.
• Patients with combined dyssynchrony exhibit superior reverse remodeling after CRT.
• Integrating both electrical and mechanical criteria may optimize patient selection for CRT.