Abstract 2673: Distinguishing Epicardial Fat From Scar: Analysis of Electrograms Using High Density Electroanatomic Mapping in a Novel Porcine Infarct Model
Background Epicardial fat can confound the quantification of scar during electroanatomic mapping. The electrogram characteristics of epicardial fat have not been compared to infarction utilizing histopathologic confirmation.
Methods: Infarction was created in pigs by occlusion of a circumflex obtuse marginal branch for 150 minutes using an angioplasty balloon. After 4–10 weeks, combined endocardial and epicardial mapping was performed using CARTO mapping system. Mapping points were acquired until the entire ventricle was sampled (fill threshold <15) and high density mapping was performed in the region infarct, border zone, epicardial vessels, and along the mitral valve annulus. Low voltage areas were defined as <1.5mV and dense scar was <0.5mV. Electrograms in low voltage regions were analyzed and bipolar amplitude, duration, number of deflections, and the presence of late potentials were recorded. After euthanization, gross pathologic examination confirmed areas of epicardial fat and visible scar.
Results: Three hearts were analyzed after high density mapping (328 points, mean) in the epicardium was performed. The mean bipolar electrogram amplitude was similar in fat and scar (0.74±0.35 vs 0.78±0.35mV; P=NS). The mean electrogram duration (61.68±17.0ms vs. 50.14±13.18; P<0.0001) was longer in fat than scar and exhibited more fractionation (2.07±0.67 vs 2.89±1.05 deflections; P<0.0001). The presence of late potentials had a specificity of 93% for scar.
Conclusion: Epicardial fat and scar are both represented by areas of low voltage by electroanatomic mapping. Scar from infarction exhibits more fractionation and longer electrogram duration when compared to fat.