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Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
Published on: December 11, 2017
Optimal left ventricular endocardial pacing sites for cardiac resynchronization therapy in patients with ischemic
David D Spragg1, Jun Dong, Barry J Fetics
1Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21224, USA. dspragg1@jhmi.edu
Insights
Optimizing cardiac resynchronization therapy (CRT) in ischemic cardiomyopathy (ICM) requires individualizing left ventricular (LV) endocardial pacing sites. Best LV endocardial pacing improves mechanical response more than standard CRT.
Area of Science:
- Cardiology
- Electrophysiology
- Heart Failure Management
Background:
- Cardiac resynchronization therapy (CRT) improves outcomes in heart failure but response varies, especially in ischemic cardiomyopathy (ICM).
- Endocardial biventricular (BiV) pacing offers potential for optimized left ventricular (LV) lead placement.
- Optimal LV endocardial pacing sites in ICM patients remain largely undefined.
Purpose of the Study:
- To investigate the impact of specific LV pacing sites on mechanical response to CRT in patients with ICM.
- To determine if endocardial BiV pacing can improve CRT efficacy compared to standard pacing in ICM.
Main Methods:
- Measured peak rate of LV pressure increase (dP/dt(max)) during VDD and BiV pacing at various LV endocardial sites in 11 ICM patients.
- Utilized electroanatomic mapping to identify optimal pacing regions achieving >=85% of maximal dP/dt(max).
- Compared endocardial pacing with existing epicardial CRT leads in 7 patients.
Main Results:
- Endocardial BiV pacing significantly improved dP/dt(max) compared to right ventricular apex pacing (241 +/- 38 mm Hg/s increase).
- The best LV endocardial pacing site yielded superior dP/dt(max) compared to pre-implanted epicardial CRT leads (111 +/- 25 mm Hg/s increase).
- Optimal sites varied individually, often located in basal lateral walls, remote from infarct zones; standard mid-LV pacing was suboptimal in 73%.
Conclusions:
- Best LV endocardial pacing sites enhance CRT effectiveness in ICM patients beyond standard coronary sinus lead placement.
- Patient-specific LV endocardial pacing site selection is crucial for optimizing CRT outcomes in ICM.
Objectives:
We sought to investigate the impact of left ventricular (LV) pacing site on mechanical response to cardiac resynchronization therapy (CRT) in patients with ischemic cardiomyopathy (ICM).
Background:
CRT reduces morbidity and mortality in patients with dyssynchronous LV failure; however, variability in response, particularly in ICM patients, poses ongoing challenges. Endocardial biventricular (BiV) stimulation may provide more flexibility in LV site selection and yield more natural transmural activation patterns. Whether this applies to ICM and whether optimal LV endocardial pacing locations vary among ICM patients remain unknown.
Methods:
Peak rate of LV pressure increase (dP/dt(max)) was measured at baseline, during VDD pacing at the right ventricular apex, and during BiV pacing from the right ventricular apex and 51 +/- 14 different LV endocardial sites in patients with ICM (n = 11). Seven patients already had an epicardial LV lead (CRT) in place, allowing comparison of epicardial BiV stimulation with that using an endocardial site directly transmural to the CRT-coronary sinus lead tip. Electroanatomic 3-dimensional maps with color-coded dP/dt(max) response defined optimal pacing regions delivering >or=85% of maximal increase in dP/dt(max).
Results:
Endocardial BiV pacing improved dP/dt(max) over right ventricular apex pacing in all patients (mean increase 241 +/- 38 mm Hg/s; p < 0.0001). In patients with pre-existing CRT leads, LV endocardial versus epicardial pacing at transmural sites yielded equivalent dP/dt(max) values. However, dP/dt(max) at the best endocardial site exceeded that achieved with the pre-implanted CRT device (mean increase 111 +/- 25 mm Hg/s; p = 0.004). An average of approximately 2 optimal endocardial sites were identified for each patient, located at the extreme basal lateral wall (8 of 11 patients) and other regions (9 of 11). Standard mid-LV free wall pacing yielded suboptimal LV function in 73% of patients. Optimal pacing sites were typically located in LV territories remote (9.3 +/- 3.6 cm) from the infarct zone.
Conclusions:
CRT delivered at best LV endocardial sites is more effective than via pre-implanted coronary sinus lead pacing. The location of optimal LV endocardial pacing varies among patients with ICM, and individual tailoring may improve CRT efficacy in such patients.
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