Quantitative comparison between amyloid deposition detected by 99mTC-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). (99m)Tc-3,3-diphosphono-1,2-propanodicarboxylic-acid-scintigraphy ((99m)Tc-DPD) was used to quantify CA. (99m)Tc-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 (ρ=0.72), E/E' (ρ=0.46) and GLS (ρ=-0.40). CONCLUSIONS: Myocardial deformation is impaired in a different stage of CA. The (99m)Tc-DPD HRI correlated well with morphologic, diastolic and strain abnormalities.