Abstract 2671: Characterization and Prevalence of Late Potentials in Nonischemic and Ischemic Cardiomyopathy: A Comparison of Arrhythmogenic Ventricular Substrates
Introduction Late potentials (LPs) are frequently found in postmyocardial infarction scar and can be a sensitive guide to target ablation of critical isthmuses. The relative prevalence and characteristics of LPs in patients with nonischemic cardiomyopathy is unknown.
Objective The purpose of this study was to compare the characteristics and prevalence of LPs within scar tissue in patients with cardiomyopathy of nonischemic (NICM) and ischemic (ICM) etiologies.
Methods Thirty-three patients with structural heart disease (NICM: 16, ICM: 17) referred for catheter ablation of ventricular tachycardia (VT) were analyzed. Electroanatomic mapping was performed endocardially (n=33) and epicardially (n=19). LPs were defined as any local electrogram with a low voltage area (LVA: ≤1.5mV) with an offset outside of the surface QRS. Very late potentials (VLP) were defined as electrograms with a width of >150 msec.
Results The average number of points sampled was 564±449 and 726±483 in the LV endocardial and epicardial maps, respectively. The mean LVA (endocardial and epicardial) in patients with ICM was 101±55 and 56±33 cm2, compared to NICM was 55±41 and 48±31 cm2. VLP were significantly more observed in LVA in ICM than NICM in endocardium (8.6±5.1 vs 4.2±5.5%; p=0.02) and epicardium (11.6±4.6 vs 3.2±2.6%, p<0.001). VLP targeted catheter ablation was effective to the patients with ICM, while patients in NICM devoid of LP have a less favorable outcome with respect to ablation.
Conclusion The electrical footprint of scar tissue is different between ICM and NICM groups. The relative paucity of LP in NICM group may account for why this population remains a challenge when referred for ablation of VT.