Role of Electrical Delay in Cardiac Resynchronization Therapy Response
Zain S Gowani1, Brett Tomashitis1, Chau N Vo1
1Department of Medicine, Medical University of South Carolina, 25 Courtenay Drive, MS-492, Charleston, SC 29425, USA.
Cardiac Electrophysiology Clinics
|June 17, 2022
Summary
Optimizing cardiac resynchronization therapy (CRT) involves targeting electrical delays, not just traditional anatomical left ventricular (LV) lead placement. Physiologic predictors like LV and interventricular delay significantly improve CRT response.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Traditional left ventricular (LV) lead placement for cardiac resynchronization therapy (CRT) relied on anatomical criteria, primarily pacing the LV lateral wall.
- Large clinical trials indicated minimal impact of specific LV lead positions on patient outcomes, with a notable exception of worse outcomes associated with apical placements.
- The limited correlation between anatomically guided LV lead placement and CRT success prompted a shift in strategy.
Purpose of the Study:
- To investigate the shift in focus for LV lead placement in CRT from anatomical to physiological predictors.
- To highlight the predictive value of mechanical and electrical activation delays in determining CRT response.
- To underscore the importance of targeting specific areas of delayed activation within the left ventricle.
Main Methods:
- Review of large clinical trials and studies concerning LV lead positioning in CRT.
- Analysis of outcome data based on traditional anatomical LV lead placement versus physiological targeting.
- Evaluation of the predictive power of left ventricular and interventricular delays on CRT response.
Main Results:
- Anatomical LV lead position, other than avoiding the apex, showed little effect on CRT outcomes.
- Physiological predictors, specifically measures of left ventricular delay and interventricular delay, emerged as strong indicators of CRT response.
- Focus has moved towards identifying and pacing areas of delayed electrical and mechanical activation for improved CRT efficacy.
Conclusions:
- Physiological targeting of electrical delays is superior to traditional anatomical LV lead placement for optimizing CRT.
- Measures of left ventricular and interventricular delay are crucial for predicting patient response to CRT.
- Future CRT strategies should prioritize pacing in regions with significant electrical dyssynchrony.
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