Myotonic dystrophy, mitral valve prolapse, and cerebral embolism.

CARDIAC abnormalities are the rule in hereditary myopathy, and myotonic dystrophy (MD) is no exception. Conduction disturbances are most common, manifested by first degree atrioventricular block,intraventricular conductive defect, and by evidence of disease in the entire conductive system on His bundle electrogram. The association between mitral valve prolapse (MVP) and MD has been reported as a familial trait. Cook et al have reported a patient with MD, MVP, and cerebral infarction. However, there are grounds for questioning the source of the embolism in their patient. We report a second patient with MD, MVP, and a transient ischemic attack in whom we believe the mitral valve was the source of the embolization.