Myocardial characterization using late enhancement photon-counting detector CT in ventricular arrhythmia: comparison with electroanatomical mapping.

Objectives: This study aimed to assess the feasibility of left ventricular myocardial characterization in patients with ventricular arrhythmias using late enhancement (LE) photon-counting detector computed tomography (PCD-CT) scans, in comparison with invasive endocardial electroanatomical mapping (EAM).

Materials and methods: This single-center retrospective observational study included 20 patients (mean age 64 ± 8 years, 4 female) who underwent PCD-CT prior to 3D endocardial uni- and bipolar EAM and radiofrequency catheter ablation (RFCA) between May 2022 and February 2024. Sixteen patients (80%) had cardiac implantable electronic devices. Twelve (60%) had ischemic and 8 (40%) had non-ischemic cardiomyopathy. Pathologic myocardial segments were defined by low-voltage electrograms < 5 mV in unipolar and < 0.5 mV in bipolar maps. Cardiac scans included LE acquisitions 5 min after contrast injection in the ECG-triggered sequential mode. Myocardial extracellular volume was computed from cardiac LE scans and visualized as polar and atlas maps (the latter depicting wall thickness) to identify pathologic segments with fibrosis and/or scar. LE scans were compared with EAM.

Results: In patients with ischemic cardiomyopathy, agreement of pathologic segments on CT was good with unipolar EAM (κ = 0.655 ± 0.249), and moderate with bipolar EAM (κ = 0.547 ± 0.267). In patients with non-ischemic cardiomyopathy, agreement of pathologic segments on CT was moderate compared with unipolar (κ = 0.455 ± 0.356) and fair with bipolar EAM (κ = 0.255 ± 0.260).

Conclusions: Preliminary evidence suggests that characterization of pathologic myocardial segments using LE PCD-CT scans is feasible and yields good agreement with endocardial EAM, particularly when compared with unipolar EAM and in patients with ischemic cardiomyopathy.

Critical relevance statement: Characterization of pathologic left ventricular segments using myocardial extracellular volume and thickness representations from spectral late enhancement photon-counting detector CT scans indicates good agreement with unipolar endocardial electroanatomical mapping, particularly in patients with ischemic cardiomyopathy.

Key points: Cardiac late enhancement imaging with photon-counting detector CT may enable characterization of pathologic myocardial segments in ventricular arrhythmia. Myocardial extracellular volume and thickness representations yield good agreement with unipolar endocardial electroanatomical mapping, particularly in patients with ischemic cardiomyopathy. Left ventricular myocardial characterization is feasible with late enhancement photon-counting detector CT and may complement invasive radiofrequency catheter ablations.