A patient presents with dyspnea and heart failure; CMR shows global hypertrophy, poor annular motion, and biatrial enlargement. What is the likely diagnosis?

• A. Dilated cardiomyopathy
• B. Hypertrophic cardiomyopathy
• C. Cardiac amyloidosis
• D. Anderson-Fabry disease

Answer: (C)

Global LV thickening with poor annular motion and biatrial enlargement on CMR points to an infiltrative, restrictive process such as cardiac amyloidosis. The amyloid deposits cause diffuse (concentric) thickening of the ventricular walls, making the ventricle stiff and impairing relaxation. That diastolic dysfunction raises filling pressures, which leads to enlargement of both atria as they work harder to fill the stiff ventricles. Infiltrative disease often has widespread myocardial involvement and characteristic enhancement patterns on CMR that support amyloidosis.

This differs from dilated cardiomyopathy, where the ventricles are enlarged and systolic function is reduced rather than thickened. Hypertrophic cardiomyopathy typically shows asymmetric wall thickening (often septal) with preserved or hyperdynamic systolic function and possible outflow obstruction, not the global thickening and biatrial enlargement seen here. Anderson-Fabry disease can cause LV hypertrophy too, but the pattern and imaging features (including LGE distribution and tissue characteristics) are not as consistent with this presentation as are those of amyloidosis.