Files in this Data Supplement:

• Movie - (AVI) (6 MB) Top Panels: Parasternal long axis (left) and short axis (right) views from a patient with HCM caused by a mutation in the cardiac β-myosin heavy chain gene. There is marked left ventricular hypertrophy in a typical pattern of asymmetric septal hypertrophy (maximal interventricular (IVS) thickness 30 mm; posterior wall (PW) 13 mm) with low normal LV cavity size and vigorous systolic function. Systolic anterior motion (SAM) of the mitral valve is seen and there is mild left atrial enlargement.
  Bottom Panels: Parasternal long axis (left) and short axis (right) views from a patient with metabolic cardiomyopathy caused by a mutation in the LAMP2 gene. There is massive concentric left ventricular hypertrophy (IVS and PW wall ≈35 mm) with small left ventricular cavity size and normal LV systolic function. No SAM is present at rest. Although LAMP2 mutations are typically associated with concentric hypertrophy and sarcomere mutations are typically associated with asymmetric septal hypertrophy as shown in these echo loops, the distribution and pattern of LVH is variable in sarcomere mutation HCM and it is consequently difficult to distinguish between metabolic cardiomyopathies and HCM based on non-invasive imaging alone. Genetic testing may assist in providing further diagnostic clarity.