Differential diagnosis of hypertrophic cardiomyopathy, fabry cardiomyopathy and cardiac amyloidosis: insights from right ventricular strain imaging echocardiography

Purpose This study aims to evaluate the diagnostic value of right ventricular (RV) myocardial assessment using two-dimensional speckle-tracking echocardiography (2D-STE) in differentiating hypertrophic cardiomyopathy (HCM), Fabry cardiomyopathy (FC), and wild-type transthyretin amyloidotic cardiomyopathy (ATTR-CM), given the clinical importance of accurate diagnosis for guiding treatment and prognosis. Methods A retrospective study was performed involving ninety consecutive patients with nonobstructive sarcomeric HCM, FC or wild-type ATTR-CM, thirty from each disease, referred to a tertiary cardiomyopathy consultation. Thirty matched healthy individuals served as controls. All participants underwent echocardiographic evaluation of RV morphology and RV myocardial mechanics using 2D-STE. RV global longitudinal strain, RV free wall longitudinal strain, and the RV apical sparing ratio were derived and diagnostic performance of RV parameters for differentiating ATTR-CM, FC, and HCM was assessed using receiver operating characteristic (ROC) curve analysis. Inter- and intra-observer reproducibility was assessed using Bland-Altman analysis. Results RV hypertrophy was significantly more prevalent in ATTR-CM and FC (100% and 97%, respectively) than in HCM (60%). ATTR-CM patients exhibited the most substantial RV strain impairment compared to FC and HCM. RV strain analysis led to significant reclassification of RV systolic dysfunction prevalence in all groups. RV global longitudinal strain, RV free wall longitudinal strain and RV apical sparing ratio emerged as effective parameters for distinguishing ATTR-CM from FC (AUC 0.91, AUC 0.89 and AUC 0.85; respectively). RV wall thickness (RVWT) was the best discriminative parameter for distinguishing ATTR-CM from HCM (AUC 0.98) and FC from HCM (AUC 0.91), followed by RV apical sparing ratio (AUC 0.94 and AUC 0.75, respectively). Excellent inter- and intra-observer agreement was observed. Conclusions Our study underscores the importance of RV assessment in differentiating HCM phenocopies. RV strain parameters and RVWT may play pivotal roles in distinguishing these conditions, facilitating earlier diagnostic and specific treatment initiation. Further research is required to assess their clinical implications.