Abstract 9250: Endocardial Electrogram Characteristics Indicating an Epicardial Origin of Focal Ventricular Arrhythmias

Abstract

Introduction: While most ventricular arrhythmias (VA) can be ablated successfully using an endocardial (ENDO) approach, epicardial (EPI) mapping and ablation is sometimes required. There may be clues on the surface electrocardiogram related to intrinsicoid deflection and QRS width; however, identification of an EPI origin of VA with certainty remains problematic, and there are no reported ENDO electrogram (EGM) characteristics that may direct ablation strategy. Methods: All patients referred for ablation of ventricular tachycardia or frequent ventricular ectopy from June 2006 through July 2010 were evaluated. Only patients with completed electroanatomical activation maps of a focal VA from ENDO and EPI were included. EGMs recorded by a bipolar mapping catheter in the area of earliest ENDO activation were analyzed and compared to the area of early EPI activation. Results: There were 17 patients with completed ENDO and EPI electroanatomical maps of a focal VA identified. We identified 3 characteristics from ENDO mapping that consistently indicated an EPI VA origin: 1) Diffusely early activation (> 2cm2 region of sites with equally earliest activation within 10 msec; figure); 2) Sequence of a far-field EGM followed by a near-field EGM in the region of earliest ENDO activation; and 3) Inability to capture the far-field component of the earliest ENDO EGM (stimulus-QRS < egm-QRS time) or reproduce the PVC or VT QRS complex morphology with pacing at the earliest ENDO activation site. Conclusions: The presence of a diffuse area of early activation and inability to capture a far-field electrogram from the endocardium indicates an epicardial origin of a focal ventricular arrhythmia.