Longitudinal Displacement vs. Strain in Cardiac Amyloidosis: A Speckle Tracking Echocardiography Study

Background: Longitudinal strain is central to the echocardiographic diagnosis of cardiac amyloidosis, typically showing reduced global values with relative apical sparing. Longitudinal displacement-an absolute measure of myocardial motion-may provide complementary diagnostic and physiological information. Methods: We retrospectively studied 24 patients with cardiac amyloidosis and 24 age-, sex-, rhythm-, and ejection fraction-matched controls. Global and regional longitudinal strain and displacement were calculated. Diagnostic performance was evaluated using receiver-operating characteristic (ROC) analysis, and reproducibility was assessed using intraclass correlation coefficients (ICC), coefficient of variation (CV), and Bland-Altman analysis. Results: In amyloidosis, both global longitudinal strain (GLS) and global longitudinal displacement (GLD) were significantly reduced compared with controls (GLS: -10.2 ± 2.6% vs. -20.1 ± 2.4%, p < 0.0001; GLD: 6.6 ± 1.9 mm vs. 11.9 ± 1.4 mm, p < 0.0001). Amyloidosis was characterized by pronounced impairment of basal displacement (9.0 ± 4.4 vs. 17.0 ± 3.9 mm, p < 0.0001) and only modest reduction in absolute apical motion (3.0 ± 2.4 vs. 5.0 ± 2.3 mm, p < 0.0001), supporting the concept that apical sparing observed on strain reflects relative rather than absolute preservation of function. ROC analysis demonstrated strong discriminatory performance within this cohort for GLD (cutoff 8.8 mm), basal displacement (~13 mm), and GLS (absolute 15.8%), with areas under the curve approaching 1.0. GLD and GLS correlated with indices of diastolic burden and functional status (E/E' and NYHA; |r| ≈ 0.32-0.41, all p ≤ 0.03). Reproducibility was good to excellent (ICC ≈ 0.84-0.89; CV 6-8%). Conclusions: Longitudinal displacement provides complementary and reproducible information alongside strain in cardiac amyloidosis. Combined assessment-reduced global or basal displacement together with reduced GLS and/or relative apical sparing-may refine the echocardiographic characterization of amyloid cardiomyopathy and link longitudinal mechanics to diastolic dysfunction and heart-failure burden.