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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
Paced left ventricular QRS width and ECG parameters predict outcomes after cardiac resynchronization therapy:
Jeff M Hsing1, Kimberly A Selzman, Christophe Leclercq
1Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
Insights
Left bundle branch features and QRS width predict cardiac resynchronization therapy (CRT) success. These ECG markers can optimize lead placement for improved patient outcomes in heart failure.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Cardiac resynchronization therapy (CRT) is established for heart failure patients with specific criteria (NYHA class III-IV, EF ≤ 35%, QRS ≥ 130 ms).
- However, 30-45% of patients do not improve clinically or echocardiographically with current CRT implant criteria.
- Predictors of Response to CRT (PROSPECT)-ECG trial aimed to identify factors influencing CRT efficacy.
Purpose of the Study:
- To identify electrocardiogram (ECG) predictors of positive outcomes in cardiac resynchronization therapy (CRT).
- To explore novel intraprocedural methods for optimizing coronary sinus lead placement during CRT implantation.
Main Methods:
- Prospective observational study analyzing ECGs before, during, and after CRT implantation.
- Primary outcomes: clinical composite score improvement and >15% LVESV reduction at 6 months.
- Multivariable logistic regression analyzed numerous baseline and procedural ECG parameters, including QRS width and morphology.
Main Results:
- Left bundle branch block morphology on baseline ECG predicted both clinical composite score and LVESV response.
- LV-paced QRS width predicted LVESV reduction, with widths ≤ 200 ms being specific for nonischemic cardiomyopathy.
- The difference between biventricular (Bi-V) and preimplantation QRS width predicted clinical composite score improvement.
Conclusions:
- Baseline ECG features, specifically left bundle branch QRS morphology, are significant predictors of CRT response.
- LV-paced QRS width and the change in QRS width with Bi-V pacing offer valuable prognostic information.
- These ECG parameters may enable intraprocedural optimization of CRT lead placement for improved patient outcomes.
Background:
For patients with symptomatic New York Heart Association class III or IV, ejection fraction ≤ 35%, and QRS ≥ 130 ms, cardiac resynchronization therapy (CRT) has become an established treatment option. However, use of these implant criteria fails to result in clinical or echocardiographic improvement in 30% to 45% of CRT patients.
Methods And Results:
The Predictors of Response to CRT (PROSPECT)-ECG is a substudy of the prospective observational PROSPECT trial. ECGs collected before, during, and after CRT implantation were analyzed. Primary outcomes were improvement in clinical composite score (CCS) and reduction of left ventricular end systolic volume (LVESV) of >15% after 6 months. Age, sex, cause of cardiomyopathy, myocardial infarction location, right ventricular function, mitral regurgitation, preimplantation QRS width, preimplantation PR interval, preimplantation right ventricular-paced QRS width, preimplantation axis categories, LV-paced QRS width, postimplantation axis categories, difference between biventricular (Bi-V) pacing and preimplantation QRS width, and QRS bundle branch morphological features were analyzed univariably in logistic regression models to predict outcomes. All significant predictors (α=0.1), age, and sex were used for multivariable analyses. Cardiomyopathy cause interaction and subanalyses were also performed. In multivariable analyses, only QRS left bundle branch morphological features predicted both CCS (odds ratio [OR]=2.46, P=0.02) and LVESV (OR=2.89, P=0.048) response. The difference between Bi-V and preimplantation QRS width predicted CCS improvement (OR=0.89, P=0.04). LV-paced QRS width predicted LVESV reduction (OR=0.86, P=0.01). Specifically, an LV-paced QRS width of ≤ 200 ms was predictive of nonischemic LVESV reduction (OR=5.12, P=0.01).
Conclusions:
Baseline left bundle branch QRS morphological features, LV-paced QRS width, and the difference between Bi-V and preimplantation QRS width can predict positive outcomes after CRT and may represent a novel intraprocedural method to optimize coronary sinus lead placement.
Clinical Trial Registration:
URL: http://www.clinicaltrials.gov. Unique identifier: NCT00253357.
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