Photon-counting detector computed tomography correlates with invasive electroanatomical mapping for myocardial substrate characterization in patients with structural heart disease

Abstract Background Characterization of the myocardial substrate by non-invasive imaging has been proven useful to guide invasive 3D electroanatomical mapping (EAM) and catheter ablation (CA) of ventricular arrhythmias (VA) in patients with structural heart disease. Cardiac magnetic resonance tomography is considered as the current gold standard for pre-procedural non-invasive delineation of the myocardial substrate, but is limited by incompatible cardiac implantable electronic devices (CIED), imaging artefacts in CIED patients and claustrophobia. Purpose To assess the utility of photon counting detector computed tomography (PCD-CT), a novel and rapid non-invasive imaging tool, for myocardial substrate delineation and its correlation with invasive 3D EAM. Methods This single-center retrospective observational study included 20 patients (12 [60%] with ischemic and 8 [40%] with non-ischemic cardiomyopathies), who underwent pre-procedural PCD-CT and 3D EAM-guided radiofrequency CA of VA between May 2022 and February 2024. Cardiac PCD-CT scans included angiographic and late enhancement (LE) acquisitions 5 minutes after contrast injection in the ECG-gated sequential mode. Endocardial 3D uni- and bipolar EAM of the left ventricle were performed with a multipolar mapping (Pentaray) and focal radiofrequency ablation (Thermocool) catheter using CARTO V3 (all Biosense Webster). Low voltage areas were defined as <5 mV in unipolar and <0.5 mV in bipolar maps. Myocardial segments with scars identified on polar and atlas maps from cardiac LE scans were compared with low voltage areas on invasive 3D EAM, and concordance of pathologic segments was calculated per patient between both modalities. Results Mean age was 64±8 years, 4 patients (20%) were female and CIEDs were present in 14 patients (70%). In patients with ischemic cardiomyopathy, unipolar and bipolar EAM identified 9±3 and 8±3 low voltage segments, and in patients with non-ischemic cardiomyopathy, 9±6 and 4±2segments, respectively. In patients with ischemic cardiomyopathy concordance between cardiac LE scans and unipolar EAM was high (defined as >75% concordance of segments) in 10 (83%) patients and moderate (defined as 50-75%) in 2 (17%) patients; concordance between cardiac LE scans and bipolar EAM was high in 7 (59%) and moderate in 5 (41%) patients. In patients with non-ischemic cardiomyopathy concordance was high in 5 (63%), moderate in 2 (25%) patients and low (defined as 25-50% concordance of segments) in 1 patient (12%) for unipolar EAM, whereas concordance was high in 2 (25%), moderate in 4 (50%), and low in 2 patients (25%) for bipolar EAM. Conclusion Myocardial substrate characterization with cardiac PCD-CT yields a strong concordance with left ventricular unipolar EAM, particularly in patients with ischemic heart disease, and may constitute an alternative for pre-procedural imaging in patients referred for CA of VA.