Iron deficiency is associated with adverse outcome in Eisenmenger patients

Abstract

Iron deficiency is common in patients with Eisenmenger syndrome (ES). This study aimed at evaluating (i) whether iron deficiency is related with adverse outcome, (ii) the determinants of iron deficiency, and (iii) the relation between iron reserves and haemoglobin level in a contemporary cohort of ES patients. All ES patients, older than 18 years, selected from the Belgian Eisenmenger registry, were prospectively followed using a web-based registry. Univariate Cox-regression analysis was performed to evaluate the relation with outcome, defined as all-cause mortality, transplantation, and hospitalisation due to cardiopulmonary causes. Bivariate analysis was performed where applicable. A total of 68 patients with a complete dataset (mean age 36.9 ± 14.2 years; 30.9% male) were included. During a median follow-up time of 3.1 years, 21 patients (30.9%) reached the predefined endpoint. New York Heart Association (NYHA) class ≥ III (HR 4.76; 95% CI 1.84-12.30; P = 0.001), iron deficiency (HR 5.29; 95% CI 2.04-13.76; P = 0.001), mean corpuscular volume (MCV) (HR 0.94; 95% CI 0.90-0.99; P = 0.021), and mean corpuscular haemoglobin (MCH) (HR 0.87; 95% CI 0.76-0.98; P = 0.027) were related with adverse outcome. The use of oral anticoagulation and frequent phlebotomies were independently related with iron deficiency (P = 0.005 and P = 0.008). In iron-deplete patients, MCV (R = -0.408; P= 0.014) and MCH (R = -0.437; P = 0.026) were inversely related with haematocrit. In patients with low oxygen saturation, iron reserves were related with haemoglobin levels (R = 0.587; P = 0.001). Iron deficiency was associated with a higher risk of adverse outcome. Moreover, the use of oral anticoagulation OAC and frequent phlebotomies were related to iron deficiency. Patients under anticoagulation should be monitored rigorously for iron deficiency. However, in patients with low oxygen saturations, careful iron substitution to avoid too high haemoglobin levels is suggested.