Abstract 16366: FDG PET Myocardial Metabolism Differentiates Electrophysiological Voltage Scar, Border Zone and Healthy Points in Patients Undergoing Ischemic Ventricular Tachycardia Ablation
Introduction: Left ventricular (LV) scar and border zone (BZ) have been implicated in the arrhythmogenesis of ventricular tachycardia (VT). Assessment of myocardial viability with SPECT and PET for differentiating scar from healthy myocardium has been well established in patients with chronic CAD and LV dysfunction. In the current study, we applied image integration and 3D mapping data to determine whether 18-F fluorodeoxyglucose (FDG) PET metabolism can differentiate scar, BZ and healthy myocardial regions, as defined by electrophysiological voltage criteria. A prospective FDG PET metabolism based substrate characterization could decrease overall procedure time and decrease procedural radiation exposure.
Methods: Twenty-two patients with ischemic and non-ischemic cardiomyopathy underwent myocardial perfusion imaging with either Rubidium-82 (Rb) or Thallium-201 (Tl) and metabolic imaging with FDG PET prior to VT ablation. The left ventricular myocardium was analyzed applying the conventional AHA 17-segment model, with peak Rb or Tl perfusion data used to normalize the corresponding FDG data. Voltage points were defined by the standard clinical criteria of scar (<0.5mV), BZ (0.5-1.5mV) and normal (>1.5mV). Voltage maps were registered with FDG polar plots and ROC curves were applied to identify the best FDG cut off value for differentiating voltage scar and BZ.
Results: Among 4368 voltage points analyzed, 684 were scar, 564 were BZ and 3120 were healthy. The corresponding mean FDG values from PET for scar (41.4±25.2%), BZ (49.5±25.9%) and healthy (69.1±27.3%) differed significantly (p<0.0001). Applying ROC curves, FDG threshold value of 50% provided a sensitivity of 69% and a specificity of 69% for differentiating voltage scar (<0.5 mV) from non-scar (>0.5 mV) points with an area under the curve (AUC) of 0.74±0.01. Similarly, FDG threshold value of 55% provided a sensitivity of 70% and a specificity of 68% for differentiating abnormal voltage (<1.5 mV) from healthy (>1.5 mV) points (AUC = 0.74±0.01).
Conclusion: FDG PET myocardial metabolism can differentiate non-invasively between scar, BZ, and healthy regions, and accordingly guide substrate-guided VT ablations in a detailed point-by-point analysis.
- © 2011 by American Heart Association, Inc.