Cardiac muscle involvement in muscle disorders.

Cardiac muscle involvement is not a rare complication in muscle disorders as is most commonlyseen in muscular dystrophies. Hypertrophic and/or dilated cardiomyopathy progresses in parallel with disease progression in most of patients with Duchenne and Becker muscular dystrophies, though cardiac failure mayprecede skeletal muscle symptoms, especially in Becker form. Cardiac muscle involvement is also commonly seen in metabolic myopathies including glycogen storage diseases and mitochondrial disorders. In this issue of the Journal (1), Ohkubo et al report an interesting family with myopathy and atrioventricular (AV) block.