Abstract 11483: Possible Criteria to Prospectively Define and Characterize Myocardial Denervation in Ischemic Patients With Ventricular Tachycardia (VT) Using I123-Meta-iodobenzylguanidine-defined (I123-MIBG)
Introduction: Cardiac innervation is a critical component in ventricular arrhythmogenesis. However, a clear definition and electrophysiological characterization of denervation zone (DZ), transitional innervation zone (TZ) and normal innervation zone (NZ) does not exist, which allow a standardized use for clinical trials and image-guided treatment/ablation.
Method: 15 patients with ischemic VT undergoing VT ablation underwent pre-procedural sympathetic innervation imaging using I123-MIBG SPECT. Sequential short axis I123-MIBG images were visually classified by 2 experienced cardiac nuclear radiologists into zones of DZ, TZ, and NZ. ROC curves were used to identify the best cut-offs of normalized voxel-based signal intensities. After reconstruction and integration of 3D innervation maps with high-density electrophysiological maps, voltage and signal characteristics were determined.
Result: All patients demonstrated areas of denervation, TZ and normal innervation. Innervation defects were localized in the inferior (100%), lateral (73%), septal (60%), apical (20%) and anterior wall (6%). Normalized MIBG uptake in areas of denervation was 25% (Q1-Q3 15.3-31.7%) [min-max 4-50%], increased to 40% (Q1-Q3 30.2-43.6%) [14-72%] in the TZ (p=0.05) and was highest in normal myocardium (NZ): 67% (Q1-Q3 52.2-71.4%) [39-100%] (p<0.001). ROC curve- defined best cut-offs for DZ, TZ and NZ were <31%, 31-47 and >47%. Local electrograms in denervated myocardium (n=1487) were abnormal (83%), fractionated (10%), normal (4%) and with diastolic potentials (3%). In the TZ (n=611) signals were abnormal (82%), fractioned (14%), normal (3%) and with diastolic potentials (1%). Bipolar voltages of 1.5mV were equally commonly in denervated (35%, 36%, and 29%, p>0.05) and transition zone (35%, 35%, and 30%, p>0.05).
Conclusion: Denervated, transitional and normally innervated myocardium was best defined by <31, 31-47% and >47% tracer uptake, which provides for the first time quantitative cut-offs for future diagnostic and therapeutic trials. As voltage/signal characteristics were unable to predict innervation categories, cardiac imaging remains the critical modality to assess myocardial innervation characteristics.
Author Disclosures: M. Abdulghani: None. J. Duell: None. M. Smith: None. W. Chen: Research Grant; Modest; GE research grant. K.L. Ume: None. T. Bob-Manuel: None. V. See: None. H. Imanli: None. A. Saliaris: None. S. Shorofsky: None. V. Dilsizian: Research Grant; Significant; GE. T. Dickfeld: Research Grant; Significant; GE.
- © 2015 by American Heart Association, Inc.