Bekfani T, et al. - Researchers determined the prevalence and relation of iron deficiency (ID) to exercise capacity and quality of life (QoL) in 190 symptomatic outpatients with heart failure with preserved ejection fraction (HFpEF) (LVEF 58 ± 7%; age 71 ± 9 years; New York Heart Association 2.4 ± 0.5; body mass index 31 ± 6 kg/m²). The definition of ID was ferritin < 100 or 100–299 μg/L with transferrin saturation < 20%, and that of anemia was hemoglobin < 13 g/dL in men, < 12 g/dL in women. They performed echocardiography, cardiopulmonary exercise test, 6-minute walk test, and QoL assessment via the EQ5D questionnaire on all patients. They reported a frequent occurrence of ID as a co-morbid condition in HFpEF, as well as its relation to reduced exercise capacity and QoL. Findings showed, with increasing severity of diastolic dysfunction, ID prevalence increased.