Abstract 17511: Contrast-Enhanced Magnetic Resonance Imaging Allows Identification of Epicardial Substrate of Post-Infarction Ventricular Tachycardias
Introduction: Epicardial location of ventricular tachycardia (VT) circuit is a limitation for ablation but its prediction is troublesome. Non invasive identification of epicardial VT substrate could facilitate ablation procedures. Endocardial VT substrate can be identified by processing contrast-enhanced magnetic resonance imaging (ceMRI) of subendocardial tissue.
Hypothesis: Epicardial VT substrate may be identified by processing subepicardial tissue in ceMRI.
Methods: Myocardial infarction was provoked in 15 pigs by left anterior descending transient occlusion. 4 weeks later a ceMRI was performed. To obtain the signal intensity (SI) maps, the ventricular wall was divided into subendocardium and subepicardium and the averaged SI was projected onto 3D endocardial and epicardial shells using customized software. These maps were color coded as follows: red dense scar defined by a SI 3 SD higher than remote normal myocardium (magenta) and heterogeneous tissue (HT) in between these extremes. An SI channel was defined as a corridor of HT surrounded by lower SI than the surrounding scar tissue. An electrophysiological study with endocardial and epicardial voltage mapping (Carto system) was performed 48 hours after ceMRI. Slow conduction channels (CCs) and VT mid-diastolic or presystolic electrograms were identified, tagged and compared with the SI maps imported in the Carto system.
Results: 20 endocardial CCs were identified in 14 of 15 animals, 15 were properly identified on endocardial SI maps (75%). 12 epicardial CCs were found in 9 of 13 pigs, 7 were correctly identified on the epicardial intensity maps (58%). 14 VTs were induced (median cycle length 276 ms, range 251-366 ms). In 5 VTs the mid-diastolic/presystolic electrograms were recorded in the epicardium, all were related to epicardial CCs, and 4 (80%) of these CCs coincided with SI channels that had been previously identified on SI map.
Conclusion: SI mapping allows identification of epicardial VT substrate
- © 2012 by American Heart Association, Inc.