Imaging in cardiac resynchronization therapy: what does the clinician need?

Area of Science:

• Cardiology
• Medical Imaging
• Electrophysiology

Background:

• Current guidelines for cardiac resynchronization therapy (CRT) patient selection depend exclusively on QRS duration from surface electrocardiograms (ECG) as a proxy for cardiac dyssynchrony.
• This approach may not fully capture the complex nature of cardiac dyssynchrony or identify other critical factors influencing CRT outcomes.

Purpose of the Study:

• To explore the potential of various imaging techniques to enhance patient selection for cardiac resynchronization therapy (CRT).
• To investigate how imaging can identify specific types of cardiac dyssynchrony (atrio-ventricular, interventricular, intraventricular) and other relevant pathologies like scar tissue or right ventricular dysfunction.
• To assess the role of imaging in optimizing left ventricular lead placement and device programming.

Main Methods:

• Review of current literature and theoretical considerations regarding the application of imaging techniques in CRT.
• Focus on echocardiography, multislices-computed tomography, and magnetic resonance imaging for assessing cardiac mechanics and anatomy.
• Discussion of the potential for new echocardiographic techniques and the need for prospective multicentre trials.

Main Results:

• Imaging techniques theoretically offer superior patient selection by analyzing detailed cardiac dyssynchrony and identifying comorbidities such as myocardial scar, right ventricular dysfunction, or pulmonary hypertension.
• Echocardiography shows promise for identifying mechanical dyssynchrony, but its definitive role requires validation in large-scale clinical trials.
• Imaging modalities can aid in optimizing left ventricular lead positioning by visualizing the site of latest activation and coronary sinus anatomy, and may improve device programming.

Conclusions:

• Imaging techniques hold significant potential to refine patient selection for CRT beyond QRS duration, leading to more personalized and effective therapy.
• Further research, particularly prospective multicentre trials, is crucial to establish the clinical utility and standardize the use of echocardiography and other imaging modalities in CRT.
• Optimizing lead placement and device programming through imaging can further enhance CRT outcomes.