The role of feature-tracking strain analysis in the differentiation of cardiac amyloidosis from hypertrophic cardiomyopathy
Authors: Dohy Z , Szabo L , Pozsonyi Z , Csecs I , Toth A , Suhai F I , Czimbalmos C , Szucs A , Kiss A R , Becker D , Merkely B , Vago H 
Published: October 2021

Abstract

Cardiac magnetic resonance (CMR) examinations have an essential role in the differentiation of cardiac involvement of amyloidosis (CA) from hypertrophic cardiomyopathy (HCM). The CMR diagnosis is traditionally based on morphologic features and the pattern of late gadolinium enhancement (LGE). However, in patients contraindicated for contrast agent administration, the diagnosis can be challenging. Novel CMR techniques, including strain analysis, can help in the differentiation of these patients.
The aim of our study was to investigate the differential diagnostic and prognostic importance of feature-tracking strain analysis in patients with left ventricular hypertrophy caused by CA or HCM.
We investigated 89 HCM patients (48 males; 50±18 years) and 46 CA patients (29 males; 64±10 years) who underwent CMR examination. The left ventricular ejection fraction (LVEF), volumes (end-diastolic volume: LVEDV, end-systolic volume: LVESV, stroke volume: LVSV), mass (LVM), and the amount of LGE were quantified. Global longitudinal (GLS), circumferential (GCS) and radial (GRS) LV strain parameters, and basal, midventricular, and apical LS and CS were measured. The apex-to-base regional LS and CS ratios were calculated. The all-cause mortality of the patients was analyzed. The characteristics of groups were compared with an independent t-test or Mann-Whitney test, as appropriate. ROC curve analysis was performed to analyze the diagnostic accuracy of a parameter and to identify optimal cutoff values. The prognostic value of CMR parameters was assessed with Cox proportional hazard regression analyses. Survival probability was analyzed with Kaplan-Meier curves and compared by the log-rank test.
CA patients had significantly lower LVEF (51±11 vs. 63±8%; p&lt;0.0001), lower LVSVi (43±12 vs. 54±12 ml/m2; p&lt;0.0001), higher LVMi (94±24 vs. 79±24 g/m2; p&lt;0.001), higher amount of LGE (29±15 vs. 8±8%; p&lt;0.0001), and more impaired global and regional strain values (GRS: 55±22 vs. 93±29%; GCS: −33±10 vs. −42±8%; GLS: −18±4 vs. −25±6%; basal CS: −26±9 vs. −39±7%; basal LS: −15±4 vs. −22±6%; p&lt;0.0001) than HCM patients. The apex-to-base CS and LS ratios were higher in CA patients, suggestive of apical sparing (1.71±0.68 vs. 1.29±0.33; p&lt;0.0001; 1.88±0.76 vs. 1.57±0.62; p&lt;0.05; respectively). In the differentiation of CA and HCM, LGE, basal CS, basal LS, GRS, and GLS had the highest diagnostic accuracies (AUCs: 0.911, 0.866, 0.848, 0.859, 0.849). During the mean 2.1±2.0 years of follow-up, three HCM patients (3.4%) and 29 CA patients (63%) died (p&lt;0.0001). The significant independent predictors of mortality were a diagnosis of CA, LVSVi and basal LS.
Our results show that CMR-based strain analysis might be a useful method for differentiating cardiac involvement of amyloidosis from HCM. Furthermore, this technique provides additional information for the assessment of prognosis in this patient population.

Funding Acknowledgement
Type of funding sources: Public Institution(s). Main funding source(s): National Research, Development and Innovation Office of Hungary; Ministry for Innovation and Technology in Hungary, within the framework of the Therapeutic Development and Bioimaging programmes of the Semmelweis University