Giant Ring Mitochondria in a Patient With Heart Failure and Cerebral White Matter Disease Resulting From an MT-TL1 Mitochondrial Gene Mutation

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.