In Search of Optimal Criteria for Iron Deficiency in CHF Patients. Post-hoc Analysis of the Study "Prevalence of Iron Deficiency in Patients With Chronic Heart Failure in the Russian Federation (ID-CHF-RF)".

Aim: Comparative analysis of clinical, anamnestic, and laboratory and instrumental data of patients with chronic heart failure (CHF) and iron deficiency (ID) diagnosed according to the AHA/ESC/RSC criteria, and CHF patients diagnosed with ID based on decreased transferrin saturation (TSAT) ≤19.8% or serum iron (Fe) ≤13 μmol/l.

Material and methods: An additional analysis of the ID-CHF-RF study was performed. The analyzed population included 498 patients (198 women) with CHF. In addition to the ID criteria provided by the protocol (AHA/ESC/RSC criteria: ferritin <100 μg/l or ferritin from 100 to 299 μg/l and TSAT<20%), concentrations of ID biomarkers were assessed, which showed high sensitivity and specificity for the diagnosis of ID compared to the morphological picture of the bone marrow (TSAT<19.8% or Fe ≤13 μmol/l). Subgroups of patients with ID determined only by the AHA/ESC/RSC criteria, only by the TSAT≤19.8% and Fe ≤13 μmol/l criteria, and by both were analyzed.

Results: ID diagnosed by the AHA/ESC/RSC criteria was found in 83.1% of patients. The TSAT ≤19.8% and Fe ≤13 μmol/l criteria revealed ID in 74.5% of patients. In 341 patients (76.8%), ID was diagnosed using both criteria. Patients with ID diagnosed by the TSAT≤19.8% and Fe≤13 μmol/l criteria, compared with patients with ID diagnosed by the AHA/ESC/RKO criteria, had a 50% lower Fe (9.8 μmol/l vs. 19.4 μmol/l) and a higher incidence of anemia (43.3% vs. 23.3%) and diabetes mellitus (DM) (36.7% and 24.7%). Also, these patients had higher values of body mass index (BMI) and NT-proBNP concentration (2317 [1305;9092] vs. 1691 [709;3856] pg/ml), and lower LV EF values (41.5 [29.0;54.5]% vs. 45.0 [34.0;54.0]%), respectively. The most severe course of CHF and the greatest changes in laboratory tests associated with ID and anemia were observed in patients with ID determined by two criteria. Patients in this group were older, with a higher BMI, more frequent presence of atrial fibrillation, and higher NT-proBNP (4182 [1854;9341] pg/ml).

Conclusion: Patients with isolated low ferritin are characterized by less severe clinical and functional impairment compared to patients with low TSAT or Fe. At the same time, patients with ferritin higher than 300 μg/l and low TSAT and/or Fe were characterized by very severe CHF and a low functional status, although this may not be related with ID. Thus, the use of the ferritin-based criteria of ID may lead to overdiagnosis of ID in some patients and, at the same time, miss some of the most "severe" patients who likely require the ID correction. Patients with ID who show a decrease in all three parameters are likely to benefit most from Fe supplementation. It is advisable to perform additional studies on the effect of Fe supplements on the course and prognosis of the disease in this cohort of patients.