Simulation of peri-mitral ablation lines using photon-counting computed tomography-based mapping of atrial wall thickness and epicardial adipose tissue

Background Creating durable linear lesions in the left atrium (LA) is the prerequisite for successful catheter ablation of peri-mitral flutter. Objective Using photon-counting computer tomography (PCCT), we compared patterns of myocardial thickness (MT), epicardial adipose tissue (EAT), and length of commonly used LA lines to determine the most favorable line profile for catheter ablation. Methods 198 patients were prospectively included. PCCT of the LA was performed in all patients. After semi-automated 3-dimensional (3D)-segmentation of PCCT data, 5 ablation lines were simulated using specialized imaging software. These included an anteroseptal (AS), anteromedial (AM) and anterolateral line (AL) and superior (MIS) and inferior mitral isthmus line (MII), MT, EAT, and line length were analyzed. Results The data set included 115,763 data points along 990 simulated lines in 198 patients. Line length was shortest in MII, longest in AM. AS showed the lowest average MT values. MT interpatient variability was greatest along the MIS. EAT was distributed inhomogenously at the anterior wall with thicker layers in medial and especially lateral aspects and highest EAT levels along the AL line. When combining MT, EAT, and line length in a weighted score, AS and MII lines demonstrated the most favorable profiles for catheter ablation. Conclusion PCCT/3D-segmentation as a tool to visualize MT and EAT is very helpful to determine the most favorable line for catheter ablation of peri-mitral flutter. In a weighted score incorporating MT, EAT, and line length, AS and MII lines showed promising profiles for the creation of durable linear lesions.