Predicting response to cardiac resynchronization therapy: Use of strict left bundle branch block criteria
Alexios Hadjis1, Ahmed AlTurki1, Riccardo Proietti2
1Department of Cardiology, McGill University Health Centre, Montreal, Quebec, Canada.
Insights
Strict left bundle branch block (LBBB) criteria in heart failure patients significantly improve CRT outcomes, reducing QRS duration and increasing ejection fraction. This approach also lowers mortality rates compared to conventional LBBB.
Area of Science:
- Cardiology
- Electrophysiology
- Heart Failure Management
Background:
- Cardiac resynchronization therapy (CRT) is a proven treatment for heart failure with reduced ejection fraction (HFrEF), improving morbidity and mortality.
- The effectiveness of CRT is notably higher in patients with left bundle branch block (LBBB).
- Identifying specific criteria for LBBB that predict optimal CRT response remains crucial.
Purpose of the Study:
- To investigate whether strict left bundle branch block (LBBB) criteria predict a significant improvement in QRS duration and left ventricular ejection fraction (LVEF) following CRT.
- To compare CRT outcomes in HFrEF patients stratified by LBBB morphology: strict LBBB, conventional LBBB, and non-LBBB.
Main Methods:
- A cohort of 231 HFrEF patients receiving CRT at a single center was analyzed.
- Patients were categorized into three groups based on baseline QRS morphology: strict LBBB, conventional LBBB, and non-LBBB.
- Key outcomes included changes in QRS duration, LVEF, and all-cause mortality post-CRT.
Main Results:
- Patients meeting strict LBBB criteria (56% of cohort) showed a significant reduction in QRS duration (-20.9 ms) and a substantial increase in LVEF (+19.5%).
- These improvements were significantly greater compared to patients with conventional LBBB or non-LBBB morphology (P < 0.0001 for both).
- Strict LBBB criteria were associated with a significant reduction in all-cause mortality (OR 0.49, P = 0.046).
Conclusions:
- Strict LBBB criteria are a strong predictor of positive CRT response in HFrEF patients.
- Adherence to strict LBBB criteria leads to superior improvements in QRS duration and LVEF compared to conventional LBBB or non-LBBB.
- Utilizing strict LBBB criteria in patient selection for CRT may improve long-term outcomes, including reduced mortality.
Background:
Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in heart failure with reduced ejection fraction (HFrEF). CRT efficacy is greater in left bundle branch block (LBBB). This study aimed to determine if strict LBBB criteria predict an improved QRS duration and left ventricular ejection fraction (LVEF) response after CRT.
Methods:
HFrEF patients who received a CRT device at a single quaternary center were included. Patients were divided into three groups based on baseline QRS morphology. Group 1 consisted of patients with strict LBBB. Group 2 had conventional LBBB, and group 3 had non-LBBB morphology. Outcomes assessed included change in QRS duration after CRT, change in LVEF, and all-cause mortality.
Results:
In 231 patients, 56% of patients were in group 1, 29% were in group 2, and 15% were in group 3. Patients with strict LBBB had a significant reduction in QRS duration (-20.9 ± 12.4 ms) compared to conventional LBBB (6.7 ± 19.4 ms; P < 0.0001) and non-LBBB (3.9 ± 29.3 ms; P < 0.0001). Patients with strict LBBB had a significant increase in LVEF (19.5 ± 10.2) compared to conventional LBBB (5.3 ± 12.6; P < 0.0001) and non-LBBB (-1.3 ± 10.9; P < 0.0001). There was moderate negative correlation between changes in QRS duration and LVEF (correlation coefficient = -0.63, P < 0.0001). Strict LBBB criteria were associated with a significant reduction in mortality compared to conventional LBBB (odds ratio 0.49, 95% confidence interval 0.24 to 0.99; P = 0.046).
Conclusions:
Strict LBBB predicted a reduction in QRS duration and an increase in LVEF compared to conventional LBBB and non-LBBB morphology in patients with HFrEF who received CRT.
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