Cardiac magnetic resonance findings in mitochondrial disease: a guide for clinicians

Mitochondrial myopathies are heritable conditions caused by genetic variations in mitochondrial DNA or nuclear DNA. These result in dysfunctional cellular oxidative phosphorylation and ATP production, affecting organs with high-energy requirements such as the heart, brain and skeletal muscle. Cardiac involvement is common affecting one third of patients and includes left ventricular hypertrophy, conduction disease, Wolff-Parkinson-White syndrome, and dilated cardiomyopathy. Due to the variability in the clinical presentation, a multiparametric approach incorporating clinical, biochemical, histological/histochemical and genetic criteria is required to make the diagnosis. Cardiologists should be aware of the clinical red flags and imaging findings and how to differentiate mitochondrial cardiomyopathy from other causes of left ventricular hypertrophy. Cardiovascular magnetic resonance imaging is a highly sensitive tool for depicting myocardial abnormalities to aid in both the diagnosis of patients presenting with left ventricular hypertrophy, and in the assessment of cardiac involvement in patients with a known diagnosis of mitochondrial myopathy, as this is an independent predictor of morbidity and early mortality. The most common CMRI findings include increased maximal LV wall thickness and mass and non-ischaemic subepicardial and midwall LGE, most commonly affecting the basal inferolateral or lateral wall. Future studies should consider integrating late gadolinium enhancement imaging into risk prediction models to enhance stratification of major adverse cardiac events such as heart failure and arrhythmia. As our understanding of mitochondrial disease evolves, integrating advanced imaging with molecular diagnostics will be essential for early detection of disease, improved risk prediction and outcomes.