Abstract
Iron deficiency (ID) is an important comorbidity in heart failure with reduced ejection (HFrEF) and is highly prevalent in both anemic and non-anemic patients. In HFrEF, iron deficiency should be investigated by measurements of transferrin saturation and ferritin. There are two types of ID: absolute deficiency, with depletion of iron stores; and functional ID, where iron supply is not sufficient despite normal stores. ID is associated with worse functional class and higher risk of death in patients with HFrEF, and scientific evidence has indicated improvement of symptoms and quality of life of these patients with treatment with parenteral iron in the form of ferric carboxymaltose. Iron plays vital roles such as oxygen transportation (hemoglobin) and storage (myoblogin), and is crucial for adequate functioning of mitochondria, which are composed of iron-based proteins and the place of energy generation by oxidative metabolism at the electron transport chain. An insufficient generation and abnormal uptake of iron by skeletal and cardiac muscle cells contribute to the pathophysiology of HF. The present review aims to increase the knowledge of the pathophysiology of ID in HFrEF, and to address available tools for its diagnosis and current scientific evidence on iron replacement therapy.