Becker muscular dystrophy with early manifestation of left heart failure.

We encountered a case of dystrophin-verified Becker muscular dystrophy which exhibited left heart failure as an initial symptom but no subjective muscle weakness. Severe cardiac involvement has been thought to rarely occur in the early stage of this disease, however accurate diagnosis was limited until the dystrophin diagnosis became available. This case suggests that some cases of dilated cardiomyopathy might be Becker muscular dystrophy, and that dystrophin tests should be added to the conventional investigation of patients with dilated cardiomyopathy.