Abstract 4089: Unique Epicardial Substrate in Non-Ischemic CM: Echo Signature, Electrogram Correlates and Outcome with Substrate Based Ablation
We present a unique series of patients (pts) with non-ischemic cardiomyopathy (NICM) and unmappable ventricular tachycardia (VT) who demonstrated predominantly normal left ventricular (LV) endocardial (ENDO) voltage and abnormal epicardial (EPI) substrate defined by intracardiac echo (ICE) and fractionated electrograms (EGMS). This substrate served as an appropriate ablation target for VT. All patients underwent ICE imaging and detailed ENDO and EPI voltage mapping to further characterize the substrate and define the EGM correlates. 5 pts with NICM had increased echogenicity in the lateral epicardium by ICE imaging. Detailed LV ENDO mapping (199 ± 94.5 points) identified no voltage abnormalities in 4 pts. In one pt, a 16.2cm2 low voltage area in the LV ENDO was present and adjacent to the EPI abnormality. In all pts, detailed EPI mapping (477 ± 158 points) revealed a distinct area (20.6 ± 3.6 cm2) of low voltage (<1.0mV) that correlated with the echogenic area. These areas displayed low amplitude EGMS that were wide (>80msec), split, and late (beyond QRS). (Figure 1⇓). After excluding coronary branch vessels and the course of the phrenic nerve, all pts underwent substrate based ablation based on pace-mapping and targeting of abnormal EGMS to eliminate the targeted VT. No VT has recurred during mean follow-up of 20mo (range 1–30 mo). Unique EPI substrate in NICM, defined by echo imaging and confirmed by EGM correlates, can be successfully targeted for RF ablation to provide effective VT control.