The importance of dose optimisation in the treatment of iron deficiency in heart failure.

Treatment with ferric carboxymaltose (FCM) is limited to 1 g during one administration, which is insufficient in patients with a higher body weight or low haemoglobin (Hb). As a consequence, under-dosing might be common in clinical practice, yet the consequences remain unstudied. We retrospectively assessed all HFrEF-patients with iron-deficiency (ferritin <100 µg/l or between 100 and 300 µg/l if TSAT < 20%) receiving treatment with FCM between 2015 and 2017. This time-frame was chosen as during this we used a 1-g FCM-regimen for all patients (unless Hb = 14-15 mg/dl, than 500 mg). We compared the actual given dose versus the calculated target dose (according to the SmPC, with the difference between both being the dose deficit). We assessed the impact of dose deficits on clinical and biochemical status after 12 weeks. A total of 211 HFrEF patients were analysed. The actual given dose FCM was 918 ± 188 mg, while the calculated target dose was 1308 ± 470 mg. In 121(61%) patients, a standard dose of 1-g FCM resulted in a dose deficit, of whom 93 had a dose deficit of 500 mg and 35 had a dose deficit of 1000 mg. Follow-up was available in 81% of patients (median = 12 weeks). A dose deficit of 500 mg was associated with a 4.93 higher odds, while a dose deficit of 1000 mg was associated with a 7.78 higher odds of residual iron deficiency. After adjusting for baseline NYHA-class, a dose deficit was associated with less symptomatic improvement. During 442 ± 292 days of follow-up, 68 patients were readmitted with heart failure and 15 patients died. In an univariate model (but not in a multivariate model), a dose deficit was associated with adverse clinical outcome. A majority of HFrEF patients with iron deficiency require doses exceeding 1 g of FCM, and thus require follow-up appointments to correct a residual dose deficit. A residual dose deficit is associated with less functional and biochemical improvement.