Abstract 2233: Comparison of Anatomical and Dynamic CT-derived Parameters between Scar, Border Zone and Healthy Myocardium in Patients Undergoing Ischemic VT Ablation
Background: Image integration in commerically available 3D mapping systems is currently only used for surface reconstruction of the blood pool/endocardial interface and does not provide any additional information about the myocardial scar substrate. Anatomic and dynamic data is available from high-resolution CT scans that could potentially identify scar and border zone and facilitate ventricular tachycardia ablations.
Methods: Ten patients with ischemic cardiomypathy underwent contrast-enhanced cardiac CT prior to VT ablation. End-systole wall thickness (ESWT), end-diastole wall thickness (EDWS), wall thickening (WT) and wall motion (WM) were extracted from phase-specific, high-resolution CT. Using a 17 segment model CT criteria were compared with endocardial voltages using the standard clinical criteria of normal (<1.5mV) or abnormal myocardium (<1.5mV) as well as scar (<0.5mV) and border zone (0.5–1.5mV). As proof-of-concept, endo/epicardial surfaces were reconstructed from the CT datasets and co-registered in a 3D mapping system to guide intra-procedural voltage mapping.
Results: 50% of segments were homogenous, containing only voltages of one of the predefined voltage groups, and used for further analysis (26 abnormal/34 normal segments). EDWT, ESWT, WT and WM were 5.8±0.4mm, 5.7±0.6mm, 0±4% and 1.0±0.3mm for abnormal and 8.1±0.5mm, 10.9±0.7mm, 35.7±6.6% and 2.7±0.6mm for healthy segments, respectively. All four parameters differed significantly (P<0.05) between healthy and abnormal segments. In subgroup analyses, EDWT, ESWT, WT and WM were 6.8±1.4mm, 7.0±2.1, 0±14% and 1.3±1.1mm for scar and 4.0±1.0m, 3.7±1.2mm, 0±11%mm and 0.0±0.0mm for border zone segments. All parameters differed significantly between scar and healthy (P<0.05), border zone and healthy (P<0.05) segments respectively. Registration of endo/epicardial surfaces allowed the intraprocedural assessment of wall thickness and correctly predicted areas of abnormal endocardial voltage.
Conclusions: CT derived anatomic and dynamic parameters showed significant differences between voltage-defined normal and abnormal myocardium. Representation of such parameters such as wall thickness may facilitate the intraprocedural substrate characterization.