Abstract 16690: Multi-modality Imaging With 18-fluoro-d-glucose (fdg) Pet and Cardiac Magnetic Resonance (cmr) Imaging to Identify Metabolical Remodeling in Patients With Ischemic Ventricular Tachycardia Substrate
Introduction: Both late gadolinium enhanced (LGE) CMR scar as well as FDG-positron emission tomography (PET) have been independently validated for the assessment of ischemic ventricular scar. We hypothesized that by combining both imaging technologies (i.e. extracellular fibrosis by CMR and metabolism of surviving myocardial cells), it is possible to detect abnormal remodeling processes within the ischemic scar characterized by preferential for cytosolic glycolysis, which provide a pathophysiological basis for possible proarrhythmic adaptions within the cellular ischemic VT substrate.
Methods: Pre-ablation LGE-CMR and FDG-PET images of the left ventricle in 9 patients undergoing ablation for drug-refractory, ischemic ventricular tachycardia were reconstructed using SEGMENT (Medviso) and PCARD (pMOD) software. Using high resolution 757-segment polar plots, the presence and transmural extent of LGE CMR defined scar as well as the FDG uptake of surviving myocardial cells (normalized to perfusion) in each segment were determined. Additionally, in each segment, relative metabolic activity per mm of surviving, non-LGE myocardium was calculated and analyzed in corresponding 2D polar plots.
Results: All patients had regions of decreased FDG uptake, located inferiorly (n=4), infero-laterally (n=3), antero-apically (n=1) and laterally (n=1). The location of decreased tracer uptake matched CMR fibrosis in all patients. Overall, CMR scar was not significantly different from PET scar (187±103 segments vs 142±85 segments, p=0.3). However, significant CMR/PET mismatch pattern (differences of >20% in segmental scar area) was seen in 3 patients, with CMR>PET in all three. Quantitative segmental analysis of those mismatching areas demonstrated a >3-fold increase in relative FDG uptake (per mm3 of living tissue) compared to remote myocardium, suggesting significant metabolic remodeling.
Conclusions: This is the first-in-human demonstration that multi-modality scar imaging using high resolution CMR and molecular, metabolic PET imaging has the potential to detect regional cellular remodeling and provide new pathophysiological insights into the possible proarrhythmic cellular adaptation within the ischemic scar substrate.
Author Disclosures: K.L. Ume: None. H. Imanli: None. J. Jeudy: None. M. Smith: None. W. Chen: None. R. Vunnam: None. J. Duell: None. S. Bhatty: None. Y. Ghzally: None. A. Saliaris: None. V. See: None. S. Shorofsky: None. V. Dilsizian: None. T.M. Dickfeld: None.
- © 2016 by American Heart Association, Inc.