Cardiomyopathy in Myotonic Dystrophy

A case of 31-year-old woman with myotonic dystrophy who developed only slight cardiac symptoms has been reported. Light and electron microscopic study was performed on myocardium obtained with endomyocardial biopsy.Light microscopy revealed a considerable degree of fatty infiltration in the myocardium, slight interstitial fibrosis and degenerated myocardial cells. On electron microscopy, marked mitochondriosis and a small number of vacuoles consisting of single limiting membrane and indefinite content low in electron density were observed. Peculiar intranuclear structure and myofibrils showing partial over-contraction and indistinct Z band were also present, and these findings were discussed comparing with the previous reports.Endomyocardial biopsy seemed to be very useful to detect the myocardial changes even in the early stage of this disease, and the electron microscopic examination of the myocardium may provide the finding which is pathognomonic for the development of the cardiomyopathy in myotonic dystrophy.