Echo Parameters for Differential Diagnosis in Cardiac Amyloidosis: A Head-to-Head Comparison of Deformation and Non-Deformation Parameters

Background: A plethora of echo parameters has been suggested for distinguishing cardiac amyloidosis CA from other causes of myocardial thickening with, however, scarce data concerning their head-to-head comparison. This study aimed at comparing the diagnostic accuracy of various deformation and conventional echo parameters in differentiating CA from other hypertrophic substrates, especially in the grey zone of mild hypertrophy [maximum wall thickness (MWT)≤16 mm] or normal ejection fraction (EF). Methods & Results: We included 100 subjects; of which 40 were patients with newly-diagnosed, biopsy-proven CA (65.5±10.8 years, 65% male, 62.5% AL type), 40 hypertrophic cardiomyopathy (HCM) patients matched for demographics and MWT (60.1±14.8 years, 85% male) and 20 hypertensives (HT) with prominent myocardial remodeling. Quantifiable conventional morphological and functional parameters along with multidimensional strain and strain derived ratios-indices, previously suggested to diagnose CA, were analyzed. EF global longitudinal strain ratio (EFSR) showed the best performance to discriminate CA [area under the curve (AUC)=0.95, 95%CI(0.89-0.98), p<0.00005]. Traditional echo indices showed overall low sensitivities and high specificities [among them myocardial contraction fraction ratio had the highest AUC=0.80, 95%CI(0.7-0.87), p<0.0001]. In the challenging subgroups (MWT≤16 mm and EF>55%), EFSR remained the best predicting parameter of CA diagnosis (multiple logistic regression models p