CMR gives clue to “ragged red fibers” in the heart in a patient with mitochondrial myopathy

Mitochondrial myopathy may manifest either as isolated myopathy or as a neuromuscular multisystemic disease and is caused by genetic defects in the mitochondrial genome resulting in respiratory chain disorders. MELAS, which is characterised by mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like epsiodes due to gene mutations in the mitochondrial DNA (adenine-to-guanine transition at nucleotide pair 3243, m.3243A>G), constitutes such a mitochondrial multisystemic disease. Although hypertrophied or dilated cardiomyopathy is quite common in MELAS, there have been no cardiovascular magnetic resonance (CMR)-based studies in these patients so far. This case report represents the first case in which comprehensive CMR and endomyocardial biopsy (EMB) data were obtained in the same patient with mitochondrial myopathy. Late gadolinium enhancement (LGE) imaging demonstrated a unique pattern of myocardial damage and histological work-up revealed the presence of “ragged red fibers” (conglomerates of mitochondria) in the heart tissue verifying the diagnosis of a mitochondrial cardiomyopathy as part of the underlying mitochondrial disease MELAS.