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Vectorcardiographic QRS area as a predictor of response to cardiac resynchronization therapy
Mohammed A Ghossein1, Antonius Mw van Stipdonk2, Frits W Prinzen1
1Department of Physiology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands.
Insights
Vectorcardiographic QRS area objectively measures left ventricular activation delay, improving patient selection for cardiac resynchronization therapy (CRT). A higher pre-CRT QRS area and its reduction post-CRT predict better outcomes.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Imaging
Background:
- Cardiac resynchronization therapy (CRT) improves heart failure outcomes in patients with ventricular conduction abnormalities.
- Current electrocardiogram (ECG) criteria for CRT selection, including QRS duration and left bundle branch block (LBBB) morphology, are suboptimal.
- Existing LBBB definitions vary, leading to subjective interpretation and inconsistent CRT benefit prediction.
Purpose of the Study:
- To evaluate the efficacy of vectorcardiographic QRS area in identifying left ventricular activation delay for CRT patient selection.
- To compare the predictive value of QRS area with traditional ECG criteria for CRT outcomes.
- To investigate the impact of pre- and post-CRT QRS area on patient response to therapy.
Main Methods:
- Objective measurement of vectorcardiographic QRS area from standard 12-lead ECGs.
- Correlation analysis between pre-CRT QRS area and post-CRT echocardiographic and clinical improvements.
- Assessment of the relationship between QRS area changes and CRT benefits, independent of other factors.
Main Results:
- Vectorcardiographic QRS area accurately identifies left ventricular activation delay, outperforming current ECG criteria.
- A higher QRS area before CRT consistently predicts significant echocardiographic and clinical improvement.
- The predictive value of QRS area is largely independent of QRS morphology, duration, and patient characteristics like sex or etiology.
- Reduction in QRS area after CRT further enhances patient benefit.
Conclusions:
- Vectorcardiographic QRS area is a superior objective marker for selecting heart failure patients for CRT.
- Pre- and post-CRT QRS area measurements provide valuable prognostic information for CRT response.
- Automated QRS area analysis from ECGs could significantly enhance clinical applicability and patient selection for CRT.
Abstract:
Cardiac resynchronization therapy (CRT) is a good treatment for heart failure accompanied by ventricular conduction abnormalities. Current ECG criteria in international guidelines seem to be suboptimal to select heart failure patients for CRT. The criteria QRS duration and left bundle branch block (LBBB) QRS morphology insufficiently detect left ventricular activation delay, which is required for benefit from CRT. Additionally, there are various definitions for LBBB, in which each one has a different association with CRT benefit and is prone to subjective interpretation. Recent studies have shown that the objectively measured vectorcardiographic QRS area identifies left ventricular activation delay with higher accuracy than any of the current ECG criteria. Indeed, various studies have consistently shown that a high QRS area prior to CRT predicts both echocardiographic and clinical improvement after CRT. The beneficial relation of QRS area with CRT-outcome was largely independent from QRS morphology, QRS duration, and patient characteristics known to affect CRT-outcome including ischemic etiology and sex. On top of QRS area prior to CRT, the reduction in QRS area after CRT further improves benefit. QRS area is easily obtainable from a standard 12-lead ECG though it currently requires off-line analysis. Clinical applicability will be significantly improved when QRS area is automatically determined by ECG equipment.
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