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Updated: Aug 14, 2026
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
Magnetic resonance criteria for future trials of cardiac resynchronization therapy
Benjamin England1, Andrew Lee, Thao Tran
1Huntington Memorial Hospital, Pasadena, California, USA.
Insights
Cardiac Resynchronization Therapy (CRT) selection can be improved by measuring cardiac asymmetry and asynchrony using cardiac magnetic resonance imaging. These novel indices accurately identify heart failure patients who may benefit from CRT.
Area of Science:
- Cardiology
- Medical Imaging
- Biomedical Engineering
Background:
- Current Cardiac Resynchronization Therapy (CRT) patient selection relies on electrocardiogram (ECG) QRS duration, potentially missing candidates with disconjugate cardiac contractility.
- Heart failure management and treatment efficacy can be significantly improved with better patient stratification.
Purpose of the Study:
- To develop a robust numerical index for patient selection in CRT using cardiac magnetic resonance imaging (CMR).
- To evaluate the roles of cardiac asymmetry, asynchrony, and circumferential strain in disconjugate cardiac contractility for CRT candidate identification.
Main Methods:
- Standard CMR imaging was performed on a GE 1.5 Tesla Signa LX MRI scanner.
- MASS Analysis software was used for image analysis.
- Statistical analysis included t-tests and standardized differences to determine efficacy and statistical power.
Main Results:
- Indices of asymmetry (Ism) and asynchrony (Isn) were accurately measurable using CMR.
- These indices demonstrated excellent statistical power as surrogate markers to differentiate heart failure patients (including CRT candidates) from normal subjects.
- Asymmetry and asynchrony are critical, improvable components of dilated cardiomyopathy.
Conclusions:
- Cardiac magnetic resonance imaging-derived indices of asymmetry and asynchrony are efficacious for screening CRT patients.
- These findings suggest a potential improvement over current ECG-based selection criteria for CRT.
- Further comparison with echocardiography data is recommended to optimize outcomes for CRT.
Abstract:
Current patient selection criteria for Cardiac Resynchronization Therapy (CRT), an efficacious treatment for heart failure, include no measure of disconjugate cardiac contractility other than prolonged QRS on electrocardiogram. Using cardiac magnetic resonance imaging, we examined the roles of cardiac asymmetry, asynchrony, and circumferential strain in DCC with the principal aim of generating a robust numerical index for use in future trials of CRT. Standard cardiac magnetic resonance imaging was done on a GE 1.5 Tesla Signa LX MRI clinical scanner (GE Healthcare, Milwaukee, WI, USA) and analyzed by MASS Analysis (MEDIS, Leiden, The Netherlands). The methods were evaluated in eleven patients with advanced heart failure due to ischemic and non-ischemic cardiomyopathy, who did not qualify under current criteria for CRT, five CRT candidates pre-op and eleven normal subjects. Using t-test and standardized differences (SD = sd/diff, Power (N) = number of patients to reach p < .05) we determined efficacy. Indices of asymmetry and asynchrony (Ism and Isn, respectively) could be measured with accuracy and provided excellent statistical power when used as surrogate markers to delineate heart failure and CRT patients from control subjects. Asymmetry and asynchrony in heart contraction are both critical components of dilated cardiomyopathy that can be improved by CRT. Magnetic resonance asynchrony is efficacious in screening patients and should now be compared with recently published echocardiography data to improve outcome for this costly but valuable therapy.
