Dilated Cardiomyopathy Associated with Hyperthyroidism.

We report a case of dilated cardiomyopathy with hyperthyroidism. A 28-year-old man was admitted because of congestive heart failure and atrial fibrillation, and was newly diagnosed as having hyperthyroidism. Despite administration of antithyroid medication, he developed recurrent congestive heart failure. An echocardiogram revealed a moderately dilated left ventricle with diffuse hypokinesis. Though his thyroid function normalized, the patient's cardiac dysfunction did not improve. Beta-blocker therapy was begun with subsequent improvement in clinical symptoms. This suggests that beta-blocker treatment may be effective in patients with atrial fibrillation associated with cardiomyopathy and hyperthyroidism.