Background: Despite the recent advances in cardiac mapping, ablation of scar-related ventricular tachycardia (VT) still remains a clinical challenge. A detailed electroanatomical map is a prerequisite for accurate localization and ablation of the VT substrate.
Objective: The purpose of this study was to evaluate the feasibility and accuracy of integrating the positron emission tomography (PET)/computed tomography (CT) with the electroanatomical map and compare the accuracy of the voltage-based scar with the biological scar.
Methods: Patients undergoing radiofrequency ablation (n = 19) for scar-related VT were enrolled. CT angiography and PET scans were performed for all patients. Tomographic and volumetric data from both images were processed and coregistered using internally designed software. That image was segmented in an electrophysiology mapping system and registered to the electroanatomical map. Eight different thresholds were applied on the voltage map to define the scar. The surface areas of the biological and electrical dense scars at different thresholds were measured and compared.
Results: The PET/CT image was well integrated with the electroanatomical map with a mean surface registration error of 5.1 +/- 2.1 mm. Of the eight different thresholds defining the scar, the surface area of the scar at a threshold of 0.9 mV (68.6 +/- 49.2 cm(2)) correlated best with the surface area of the PET-based scar (70.4 +/- 49.3 cm(2)) and had the least total area error (4.8 +/- 1.8 cm(2)) compared with the 0.5 threshold (29.7 +/- 23.9 cm(2)).
Conclusion: Integrating PET/CT with the electroanatomical map is feasible and accurate. Based on the biological scar, readjustment of the voltage scar threshold to 0.9 mV is suggested. In view of the better accuracy of PET/CT in defining scar, the need for acquiring detailed voltage maps may be obviated.