Cardiac magnetic resonance circumferential strain predicts myocardial fibrosis in DMD-associated cardiac disease

Background Duchenne Muscular Dystrophy (DMD) is an X-linked recessive disease with an incidence of 1/3500 live male births. Loss of the dystrophin protein leads to progressive muscle degeneration and an absolute genetic risk of developing cardiac disease. Currently there is a lack of a sensitive diagnostic tool to identify cardiac dysfunction in early stages of the disease and standard measures of decreased global function, e.g. ejection fraction (EF), are only detectable when advanced disease is present. We found that myocardial circumferential strain (Ecc, an indicator of local myocardial deformation normalized to its original dimension) can detect occult cardiac disease early in the course of disease despite normal EF, and Ecc magnitude further declines with advancing age and disease progression. DMD associated cardiac disease leads to replacement of normal myocyte with myocardial fibrosis leading to eventual cardiac dysfunction; cardiac magnetic resonance (CMR) has been used to assess for late gadolinium enhancement (LGE, an indicator of myocardial fibrosis) in DMD patients. We sought to determine if Ecc is a predictor of myocardial fibrosis in DMD patients.