Quantitative Comparison Between Amyloid Deposition Detected by Tc-99m-Diphosphonate Imaging and Myocardial Deformation Evaluated by Strain Echocardiography in Transthyretin-Related Cardiac Amyloidosis

Background: Management of cardiac amyloidosis (CA) is related to amyloid deposition. Our aim was to assess the effect of amyloid deposition on myocardial function. Methods and Results: Twenty-eight patients with transthyretin mutation and a group of 14 controls underwent echocardiography to quantify left ventricular (LV) dimensions, function, and global (G) longitudinal (L), radial (R) and circumferential (C) strain (S). Tc-99m-3,3-diphosphono-1,2-propanodicarboxylic-acid-scintigraphy (Tc-99m-DPD) was used to quantify CA. Tc-99m-DPD revealed accumulation in 14/28 patients (CA group) and no accumulation (no-CA group) in 14. Cardiac accumulation was lower-than-bone uptake in 5 (mild-CA group) and higher-than-bone uptake in 9 (severe-CA group). Ejection fraction was similar among groups. GLS was lower (P<0.001) in the severe-CA group (-12.2 +/- 4.5) with respect to the no-CA group (-19.3 +/- 3.0) and to the control group (-20.9 +/- 2.5). Conversely, GCS and GRS were lower (P<0.05) in the mild-CA group (-10.8 +/- 4.1 and 9.5 +/- 5.7, respectively) with respect to the severe-CA group (-18.9 +/- 5.1 and 23.9 +/- 6.3 respectively), no-CA group (-19.2 +/- 4.1 and 28.4 +/- 10.2, respectively) and the control group (-23.9 +/- 4.4 and 29.9 +/- 8.7, respectively). A correlation was found between the scintigraphic heart retention index (HRI) and LV septal thickness (rho=0.72), E/E' (rho=0.46) and GLS (rho=-0.40).