Following her sister’s diagnosis, a screening echocardiogram at 13 months of age revealed mild-moderate left atrial enlargement but normal left ventricular chamber size and systolic function (EF = 60%). A surveillance study at 2 6/12 years of age was diagnostic for DCM, with moderate LV enlargement, moderate-severe LV systolic dysfunction (EF = 27%), moderate mitral valve regurgitation, and severe left atrial enlargement.

Echocardiography revealed DCM with severe four-chamber enlargement and decreased left ventricular ejection fraction (EF = 20%; normal ≥50%) in the absence of symptoms or physical findings of heart failure.