[Mitochondrial cardiomyopathy in an adult: a case history].

We report an original case of mitochondrial cardiomyopathy discovered in a young woman during an episode of cardiac decompensation. The diagnosis was suspected from the echocardiographic appearances of granite-like heterogeneous hypertrophic cardiomyopathy. It was confirmed by endomyocardial biopsies. The clinical evolution was favourable with classical treatment. Mitochondrial cardiomyopathy is a rare cause of cardiomyopathy, generally observed in children, with multisystemic localisation. The pathophysiology and genetics are complex. Cardiac involvement is observed in 25% of cases, with the principal manifestation being hypertrophic cardiomyopathy. In the absence of any specific clinical or paraclinical signs, echocardiography and MRI are the techniques of choice for morphological evaluation. Diagnosis relies upon myocardial biopsy, which should be readily advocated in every unexplained case of cardiomyopathy in a young subject. The prognosis is poor and no specific treatment is available.