Well-studied in the Ventricles, Emerging in the Atria: Left Atrial Wall Thickening in Cardiac Amyloidosis

F. Bahlke (München)¹, M. Siller (München)², F. Englert (München)³, J. Syväri (München)³, M.-A. Popa (München)³, H. Krafft (München)³, A. Tunsch Martinez (München)³, M. Tydecks (München)³, D.-P. Dischl (München)³, M. Telishevska (München)³, E. Koops (München)³, T. Reiter (München)³, M. Al Fayad (München)³, S. Lengauer (München)³, G. Heßling (München)⁴, I. Deisenhofer (München)³, N. Erhard (München)^1
1Deutsches Herzzentrum München Klinik für Herz- und Kreislauferkrankungen München, Deutschland; ²TUM Klinikum Deutsches Herzzentrum Klinik für Herz- und Kreislauferkrankungen München, Deutschland; ³Deutsches Herzzentrum München Elektrophysiologie München, Deutschland; ⁴Deutsches Herzzentrum München Klinik für Herz- und Kreislauferkrankungen, Abteilung der Elektrophysiologie München, Deutschland

Background:

Cardiac amyloidosis (CA) is an infiltrative disease leading to atrial fibrillation (AF) due to remodeling of the left atrium. Characterizing the atrial substrate in CA remains challenging. Photon-counting CT may improve atrial imaging in CA due to its superior spatial resolution.
Purpose: The aim of this study was to compare left atrial wall thickness (LAWT) and epicardial adipose tissue (EAT) in patients undergoing AF ablation with and without CA.
Methods: Pre-procedural high-resolution photon-counting CT was acquired in 117 patients undergoing first-time AF ablation. All patients were suffering from persistent AF, 13 additionally from CA. After segmentation with InHeart, quantification of LAWT and EAT was possible. Nine potential linear ablation lesions were simulated across four left-atrial regions (anterior, lateral, roof, posterior) in ParaView and a custom-developed algorithm measured line length of the ablation lesions.
Results:
In total, 1053 lines (consisting of 123830 data points) were simulated. Across all data points, mean LAWT was higher in CA (2.4 ± 1.0 mm vs. 1.8 ± 0.8 mm; p < 0.001), whereas EAT was thinner in CA (1.2 ± 1.8 vs. 1.9 ± 2.2 mm; p < 0.001). LAWT was significantly higher in every analyzed region in CA (Figure 1). EAT was significantly thinner anteriorly, posteriorly and at the roof in CA, with no difference inferiorly. Average line length did not differ between the two groups (43.4 ± 11.6 vs. 44.2 ± 10.5 mm; p = 0.45).
Conclusion:
To the best of our knowledge, this is the first study to describe diffuse thickening of the left-atrial wall in cardiac amyloidosis and concomitant reductions of epicardial adipose tissue. Our findings provide the first evidence that amyloidosis is an infiltrative disease not only of the ventricles but also of the atria. Quantifying left-atrial thickening may help in the assessment of disease progression and guide catheter ablation.