Cardiac Dysfunction in Mitochondrial Disease

(mtDNA) disease and the frequency of cardiac involvement, at least 1 in 10–15,000 of the general population will be affected.4 In 1991, the first mtDNA point mutation in the MT-TL1 gene associated with an MCM was described.5 Since then, several mutations, mostly in mitochondrial tRNA genes, have been associated with different MCM phenotypes. At the end of the 20th century, mutations in several nuclear genes encoding complex IV (CIV) assembly factors, such as SCO2 and SURF1, were identified.6 Since then, the number of nuclear genes involved in MCM has increased considerably.7–13 Taking into account that cardiac involvement is an important manifestation among patients with MD and that its prevalence is probably undervalitochondrial disorders (MD) are multisystem diseases that may arise at any age, as a result of dysfunction of the respiratory chain (RC). The most frequently and severely affected organs are those that place high demands on aerobic metabolism, such as brain and skeletal and cardiac muscle. Mitochondrial dysfunction frequently affects the heart and may cause cardiomyopathies (CM) or cardiac conduction abnormalities.1 The predominance of neurologic and neuromuscular manifestations in MD has generally masked the presence of other clinical phenotypes, such as cardiac complications, which may have prevented the diagnosis of mitochondrial CM (MCMs).2,3 Based on the prevalence of mitochondrial DNA M