Cardiomyopathy is an inevitable fate for patients with Duchenne muscular dystrophy (DMD) and is one of the major causes of mortality. Cardiovascular magnetic resonance (CMR) is increasingly being performed at very high magnetic field strength for small animal models of muscular dystrophy. The mdx mouse model is one of the most commonly used animal models for DMD. Recombinant adeno-associated viral vector-mediated gene transfer represents a promising approach for DMD. The aim of this study was to elucidate the functional impact of micro-dystrophin on cardiomyopathy in mdx mice using CMR as a non-invasive biomarker.