Background The most commonly used definition of iron deficiency (ID; ferritin <100 ng/mL or ferritin 100–300 ng/mL and transferrin saturation [TSAT] <20%) has not been validated in patients with heart failure (HF). We aimed to define and validate the biomarker-based definition of ID in HF, using bone marrow iron staining as the gold standard. Second, we aimed to assess the prognostic value of the optimized definition.

Methods and Results Bone marrow aspiration with iron staining was performed in 42 patients with HF and a reduced left ventricular ejection fraction (≤45%) undergoing median sternotomy for coronary artery bypass grafting. Patients were mostly male (76%) with mild-to-moderate HF and a mean age of 68±10 years. Bone marrow ID was found in 17 (40%) of the HF patients. The most commonly used definition of ID had a sensitivity of 82% and a specificity of 72%. A definition solely based on TSAT ≤19.8% or serum iron ≤13 µmol/L had a sensitivity of 94% and specificity of 84% and 88%, respectively (P<0.05 compared with the former definition). Subsequently, we assessed the incidence of all-cause mortality in 387 consecutive outpatient HF patients (left ventricular ejection fraction ≤45%). In these patients, TSAT ≤19.8% and serum iron ≤13 µmol/L, and not ferritin, were independently associated with mortality.

Conclusions A TSAT ≤19.8% or a serum iron ≤13 µmol/L shows the best performance in selecting patients with ID and identifies HF patients at the highest risk of death. Our findings validate the currently used TSAT cutoff of <20% for the identification of ID in HF patients, but question the diagnostic value of ferritin.

背景技术铁缺乏症（ID；铁蛋白<100 ng / mL或铁蛋白100-300 ng / mL，转铁蛋白饱和度[TSAT] <20％）最常用的定义尚未在心力衰竭（HF）患者中得到验证。我们旨在使用骨髓铁染色作为金标准来定义和验证HF中基于生物标记物的ID定义。其次，我们旨在评估优化定义的预后价值。

方法与结果42例心力衰竭，左心室射血分数降低（≤45％），正中胸骨切开术的冠状动脉搭桥术患者接受了铁染色的骨髓穿刺术。患者多数为男性（76％），患有轻度至中度HF，平均年龄为68±10岁。在17名（40％）HF患者中发现了骨髓ID。ID的最常用定义具有82％的灵敏度和72％的特异性。仅基于TSAT≤19.8％或血清铁≤13 µmol / L的定义分别具有94％的敏感性和84％和88％的特异性（P与以前的定义相比，<0.05）。随后，我们评估了387例连续的门诊HF患者（左心室射血分数≤45％）全因死亡率的发生率。在这些患者中，TSAT≤19.8％和血清铁≤13 µmol / L，而不是铁蛋白与死亡率独立相关。

结论TSAT≤19.8％或血清铁≤13µmol / L表现出最佳的ID病患选择，并确定了具有最高死亡风险的HF患者。我们的发现验证了目前使用的TSAT临界值<20％来鉴定HF患者的ID，但对铁蛋白的诊断价值提出了质疑。