Association Between Hemoglobin Levels and Efficacy of Intravenous Ferric Carboxymaltose in Patients With Acute Heart Failure and Iron Deficiency: An AFFIRM-AHF Subgroup Analysis

Background: Iron deficiency, with or without anemia, is an adverse prognostic factor in heart failure (HF). In AFFIRM-AHF (a randomized, double-blind placebo-controlled trial comparing the effect of intravenous ferric carboxymaltose on hospitalizations and mortality in iron-deficient subjects admitted for acute heart failure), intravenous ferric carboxymaltose (FCM), although having no significant effect on the primary end point, reduced the risk of HF hospitalization (hHF) and improved quality of life versus placebo in iron-deficient patients stabilized after an acute HF (AHF) episode. These prespecified AFFIRM-AHF subanalyses explored the association between hemoglobin levels and FCM treatment effects. Methods: AFFIRM-AHF was a multicenter, double-blind, randomized, placebo-controlled trial of FCM in hospitalized AHF patients with iron deficiency. Patients were stratified by baseline hemoglobin level (<12 versus ≥12 g/dL). In each subgroup, the primary composite (total hHF and cardiovascular death) and secondary (total hHF; total cardiovascular hospitalizations and cardiovascular death; time to cardiovascular death, and time to first/days lost due to hHF or cardiovascular death) outcomes were assessed with FCM versus placebo at week 52. Sensitivity analyses using the World Health Organization anemia definition (hemoglobin level <12 g/dL [women] or <13 g/dL [men]) were performed, among others. Results: Of 1108 AFFIRM-AHF patients, 1107 were included in these subanalyses: 464 (FCM group, 228; placebo group, 236) had a hemoglobin level <12 g/dL, and 643 (FCM, 329; placebo, 314) had a hemoglobin level ≥12 g/dL. Patients with a hemoglobin level <12 g/dL were older (mean, 73.7 versus 69.1 years), with more frequent previous HF (75.0% versus 68.7%), serum ferritin <100 μg/L (75.4% versus 68.1%), and transferrin saturation <20% (87.9% versus 81.4%). For the primary outcome, annualized event rates per 100 patient-years with FCM versus placebo were 71.1 and 73.6 (rate ratio, 0.97 [95% CI, 0.66–1.41]), respectively, and 48.5 versus 72.9 (RR, 0.67 [95% CI, 0.48–0.93]) in the hemoglobin levels <12 and ≥12 g/dL subgroups, respectively. No significant interactions between hemoglobin subgroup and treatment effect were observed for primary ( P interaction =0.15) or secondary outcomes. Changes from baseline in hemoglobin, serum ferritin and transferrin saturation were significantly greater with FCM versus placebo in both subgroups between weeks 6 and 52. Findings were similar using the World Health Organization definition for anemia. Conclusions: The effects of intravenous FCM on outcomes in iron-deficient patients stabilized after an AHF episode, including improvements in iron parameters over time, did not differ between patients with hemoglobin levels <12 and ≥12 g/dL. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02937454.