Background The presence of giant ring mitochondria on endomyocardial biopsy is rarely reported and does not have a well-defined differential diagnosis. Methods We report the case of a 54-year-old man with heart failure and preserved ejection fraction and left ventricular hypertrophy, initially thought to have an infiltrative cardiomyopathy. Results The patient was found to have extensive vacuolization caused by giant ring mitochondria on endomyocardial biopsy. Mitochondrial genetic testing revealed an A3243G mutation in the MT-TL1 gene, which is a mitochondrial encoded transfer RNA-leucine molecule. Conclusions Mitochondrial disease should be considered in patients presenting with unexplained cardiomyopathy and skeletal muscle, cerebral, or metabolic abnormalities. In this case, the presence of unexpected extensive cardiomyocyte vacuolization and giant, ring-shaped mitochondria on endomyocardial biopsy prompted mitochondrial genetic testing, which ultimately resulted in the correct diagnosis and treatment.
- mitochondrial disease
- mitochondrial genetics
- ring mitochondria
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine