Change in Eosinophil Count in Patients with Heart Failure Treated with Anakinra

Background: Interleukin-1 blockade with anakinra leads to a transient increase in eosinophil blood count (eosinophils) in patients with acute myocardial infarction. We aimed to investigate the effect of anakinra on changes in eosinophils in patients with heart failure (HF) and their correlation with cardiorespiratory fitness (CRF). Methods: We measured eosinophils in 64 patients with HF (50% females), 55 (51–63) years of age, before and after treatment, and, in a subset of 41 patients, also after treatment cessation. We also evaluated CRF, measuring peak oxygen consumption (VO2) with a treadmill test. Results: Treatment with anakinra significantly and transiently increased eosinophils, from 0.2 [0.1–0.3] to 0.3 [0.1–0.4] × 103 cells/µL (p < 0.001) and from 0.3 [0.2–0.5] to 0.2 [0.1–0.3] × 103 cells/µL, with suspension (p < 0.001). Changes in eosinophils correlated with the changes in peak VO2 (Spearman’s Rho = +0.228, p = 0.020). Eosinophils were higher in patients with injection site reactions (ISR) (n = 8, 13%; 0.5 [0.4–0.6] vs. 0.2 [0.1–0.4] × 103 cells/µL, p = 0.023), who also showed a greater increase in peak VO2 (3.0 [0.9–4.3] vs. 0.3 [−0.6–1.8] mLO2·kg−1·min−1, p = 0.015). Conclusion: Patients with HF treated with anakinra experience a transient increase in eosinophils, which is associated with ISR and a greater improvement in peak VO2.