USA: A recent cohort study published in JAMA Cardiology found that contrast-enhanced computed tomography (CECT) can help localize fatty tissue in the heart.
The findings revealed that CECT achieved high accuracy in the study that focused on fatty tissue insulating the atrioventricular node and the proximal specialized conduction system (AVCS) from surrounding muscle. This capability could lead to better heart treatment strategies.

“Noninvasive visualization of the AVCS may provide utility in planning for interventional, electrophysiologic, and surgical procedures by providing an anatomic roadmap,” Mirmilad Khoshknab, Hospital of the University of Pennsylvania, Philadelphia, and colleagues wrote.
The AVCS comprises muscle cells responsible for excitatory impulse transmission from the atria to the ventricle -- also known as the conducive myocardium. In cases where the system is infiltrated by fatty deposits, it predisposes patients to heart disease and complications. Previous studies indicate that CECT can identify heart structures by localizing myocardial fat with high specificity.
Against the above background, Dr. Khoshknab and colleagues tested the hypothesis that pre-procedure CECT can accurately localize the AVCS by identifying the fat that insulates the conductive myocardium.
For this purpose, the research team conducted a prospective cohort study conducted at an academic tertiary care center. It included patients with CECT acquired less than one month before atrial fibrillation ablation and electroanatomic localization of the His electrogram signal on electroanatomic mapping (EAM) between 2022 and 2023.
The study's main outcome was the distance from the His electrogram signal to the fat segmentation encompassing the AVCS on CECT, following registration of the images to EAM.
The researchers revealed that among 20 patients (mean age, 66 years; 75% males) in the cohort, the mean attenuation of the AVCS fat segmentation was 2.9 Hounsfield units. The mean distance from the His electrogram to the closest AVCS fat voxel was 3.3 mm.
Myocardial low attenuation on CECT indicating fat deposition at the top of the triangle of Koch was within the registration error range of the intracardiac His signal in all cases.
"The results suggest that CECT could accurately localize the fatty tissue that insulates AVCS from surrounding atrial and ventricular myocardium. It also enhances the safety and efficacy of procedures targeting the conduction system and structures in its proximity," the researchers concluded.
Reference:
Khoshknab M, Zghaib T, Xu L, et al. Noninvasive Visualization of the Atrioventricular Conduction System Using Cardiac Computed Tomography. JAMA Cardiol. Published online July 24, 2024. doi:10.1001/jamacardio.2024.2012