Melenovsky et al. found that the iron content in the left ventricle myocardium of human CHF patients was decreased, the activity of xanthine oxidase and malate dehydrogenase was decreased, the expression of ROS scavenger enzymes [such as catalase, glutathione peroxidase, and superoxide dismutase 2 (SOD2)] was decreased, and the energy production and contractile function of cardiomyocyte were decreased, indicating that myocardial iron deficiency may lead to mitochondrial dysfunction [77]. Here, SOD2 is linked to congestive heart failure.