Subclinical Becker's muscular dystrophy presenting with severe heart failure.

We describe a rare case of Becker's muscular dystrophy (BMD) in a 28-year-old man complicated by rapidly progressing heart failure without apparent clinical signs of neuromuscular disease. He showed rhabdomyolysis, which repeatedly occurred causing acute renal failure as heart failure worsened. His serum creatine kinase (CK) level was generally below 300 IU/l. However, it exceeded more than 10,000 IU/l at the time of myoglobinuria. This suggests that the worsening of heart failure could induce rhabdomyolysis in a BMD patient. Gene analysis for BMD should be considered when the elevation of serum CK is noted in heart failure.