Endocardial electrogram characteristics of epicardial ventricular arrhythmias

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Ablation

Background:

• Endocardial ablation is standard for ventricular arrhythmias (VA), but epicardial approaches are sometimes needed.
• Distinguishing epicardial VA origins from endocardial ones using surface ECGs and endocardial mapping is difficult.

Purpose of the Study:

• To identify reliable endocardial mapping characteristics that predict the need for epicardial ablation in patients with VA.
• To improve the accuracy of determining epicardial origin for ventricular arrhythmias.

Main Methods:

• Retrospective analysis of 10 patients with completed endocardial and epicardial electroanatomical activation maps for epicardial VA.
• Comparison of bipolar electrograms from earliest endocardial activation sites with early epicardial activation sites.
• Characterization of electrogram components as far-field if monophasic and uncapturable.

Main Results:

• Three endocardial mapping characteristics consistently indicated the need for epicardial ablation.
• These included diffusely early activation (>2 cm² region within 10 ms), a far-field followed by a near-field electrogram, and inability to capture the far-field component.
• Inability to capture was defined as stimulus-QRS time less than electrogram-QRS time.

Conclusions:

• Diffusely early activation on endocardial mapping suggests a potential epicardial origin for VA.
• An uncapturable far-field electrogram at the earliest endocardial activation site strongly indicates the need for epicardial ablation.
• These findings aid in selecting the appropriate ablation strategy for challenging ventricular arrhythmias.