Supportive Cardiac Magnetic Resonance Imaging (CMR) Features for Differentiating Hypertrophic Cardiomyopathy and Cardiac Amyloidosis.

Left ventricular hypertrophy is multifactorial and forecasts an increased risk of cardiovascular morbidity and mortality. Hypertrophic cardiomyopathy (HCM) is the most prevalent form of inherited cardiomyopathy. It results from mutations involving the genes encoding sarcomere proteins and is characterized by left ventricular hypertrophy and fibrosis. Cardiac amyloidosis (CA) is a disease where misfolded proteins accumulate in the extracellular cardiac tissue and is associated with poor prognosis. These cardiomyopathies share multiple features, and it can be challenging to differentiate between them. Timely diagnosis and differentiation between these cardiomyopathies is important. Advanced imaging modalities, namely cardiac magnetic resonance (CMR) is essential for accurate diagnosis and management. We compared 132 HCM patients, 62 CA & 20 healthy controls who completed a CMR (1.5 T or 3T) at the University of Utah Health. We examined the differences in multiple CMR parameters between these groups including left ventricular ejection fraction (LVEF), left atrial and right atrial size and emptying fraction (LAEF & RAEF), T1- tissue mapping and extracellular volume (ECV) measurement, CMR feature tracking (FT) peak segmental and global 2D and 3D strain. We used standard statistical descriptors and between-group analysis. On average, all three groups had preserved LVEF (64 ± 13) with the CA patients having low normal LVEF (52% ± 15). In comparison to HCM, the LAEF & RAEF were lower in CA (49 ± 11 vs 29 ± 15, P <0.001 & 52 ± 12.0 vs 34 ± 17, P <0.001). ECV was higher in CA when compared to HCM (53 ± 12 1.5 T & 51 ± 12 3T vs. 30 ± 7 1.5 T & 29 ± 5 3T, P<0.001). Regarding peak segmental strain, HCM exhibited lower absolute strain values compared to the control group, particularly in the basal septal segments. CA had significantly lower strain values across all segments. A relative apical sparing pattern was also noted (Figure 1). In HCM, only the global longitudinal strain was reduced, in both 2D & 3D, compared to controls (-9 ± 4 vs. -13 ± 4 2D & -7 ± 4 vs. -9 ± 4 3D, P<0.001). In CA, longitudinal, circumferential, and radial global strain, in both 2D and 3D, were reduced. CMR plays an important role in differentiating cardiomyopathies with increased left ventricular thickness. Among CMR parameters, LAEF, RAEF, ECV, peak global and regional strain, can be effective in distinguishing between HCM and CA. [ABSTRACT FROM AUTHOR]