How to recognize epicardial origin of ventricular tachycardias?

Area of Science:

• Cardiology
• Electrophysiology
• Medical Imaging

Background:

• Percutaneous pericardial access for epicardial mapping and ablation of ventricular arrhythmias has become a crucial technique.
• Its application has expanded beyond Chagas disease to other cardiomyopathies, offering insights into arrhythmia substrates.
• This approach has significantly improved ablation outcomes in diverse clinical scenarios.

Purpose of the Study:

• To review and discuss electrocardiogram (ECG) criteria for recognizing epicardial origin of ventricular tachycardias.
• To highlight the utility of these criteria in various cardiomyopathies and clinical settings.
• To inform the planning and decision-making process for epicardial ablation procedures.

Main Methods:

• Analysis of the first QRS components on ECG to identify epicardial activation patterns.
• Evaluation of parameters like pseudodelta wave, intrinsicoid deflection, and shortest RS interval for scar-related ventricular tachycardias.
• Application of the maximum deflection index for idiopathic epicardial tachycardias.
• Consideration of ECG criteria in nonischemic cardiomyopathy, including q wave in lead I.

Main Results:

• Specific ECG parameters can predict epicardial origin in scar-related ventricular tachycardias with right bundle branch block morphology.
• The maximum deflection index aids in locating idiopathic epicardial tachycardias.
• ECG criteria based on QRS morphology are proposed for nonischemic cardiomyopathy.
• These criteria are substrate-specific and have limitations.

Conclusions:

• Electrocardiogram criteria are valuable for identifying epicardial ventricular arrhythmias, guiding ablation strategies.
• Combining ECG findings with clinical data (heart disease type, prior ablation history, MRI scar evidence) optimizes epicardial approach selection.
• Further refinement of substrate-specific ECG criteria is needed for improved diagnostic accuracy.