Effect of intravenous iron replacement therapy on exercise capacity in iron deficient anemic patients after cardiac surgery

Abstract

Iron deficiency (ID) is recognized as an important comorbidity in patients undergoing cardiac surgery; however, it still remains under-diagnosed and under-treated in clinical practice. This study aims at comparing efficacy and the effects on exercise capacity of intravenous ferric carboxymaltose (FCM) versus ferric gluconate (FG) in patients with ID anemia (IDA) resulting from cardiac surgery. We retrospectively analyzed data from our records of in-hospital patients with IDA after cardiac surgery undergoing cardiac rehabilitation. Group I was treated with FG, group II with FCM. Efficacy measures included changes (baseline vs discharge) in hemoglobin (Hb) and in distance traveled at six-minutes walking test (6MWT). Data from 74 in-patients (mean age 67.5±10.4 years, 43% women) were analyzed. At discharge, patients treated with FCM showed higher levels of Hb (11.1±1.2g/dl vs 10.2±1.1 g/dl; p=0.001), greater distance traveled at 6MWT (279.2±108.8 meters vs 236.3±72.7 meters; p=0.048), and lower in-hospital rehabilitation length of stay (20.3±7 vs 25.3±11.7 days; p=0.043) as compared to FG group. At multivariate analysis, the most powerful predictors of Hb increase >1 g/dl at discharge were transferrin levels (p=0.019) and treatment with FCM (p<0.001). FCM replacement therapy and iron serum levels were the most powerful predictors of 6MWT distance improvement (>100 meters) at discharge (p=0.13 and p=0.003, respectively). In patients with IDA following cardiac surgery, intravenous FCM is effective in restoring Hb levels and in improving exercise capacity after cardiac surgery.

Short-term treatment of iron deficiency anemia after cardiac surgery

“…Furthermore, absolute ID is associated with prolonged hospital stay, at least after heart valve surgery [38] . Indeed, in clinical practice, the IDA is routinely assessed and corrected after cardiac surgery, resulting in significant clinical benefits (the faster the IDA is corrected, the faster the improvement in functional capacity) [39] .…”

“…Moreover, serum ferritin is inversely correlated with the levels of antioxidant vitamins and CRP and is used to assess clinical outcomes that are presumed to be caused by iron-driven oxidative stress [49] . Consequently, high ferritin values are common after cardiac surgery [38] , [39] , [50] . Besides the activation of inflammatory response during cardiopulmonary bypass, hemolysis, peripheral muscle damage and ischemia–reperfusion injury are also causes of hyperferritinemia, which seems to correlate with an adverse outcome [51] .…”

“…Therefore, it is hardly surprising that FCM was found to be more effective than iron gluconate in significantly increasing the 6MWT distance [39] during cardiac rehabilitation program after cardiac surgery; the improved bioavailability of FCM enables faster recovery of cardiac and skeletal muscle mitochondrial function. Conversely, SI treatment demonstrated an identical increase in the distance walked during the walk test at the end of hospital stay (T2) for SI and FCM (349.12 ± 148.22 vs. 346.35 ± 121.51, p: 0.915).…”

“…The first study [38] , confirms that absolute ID is associated with prolonged hospital stay and is more frequent in cardiac valve surgery, reasonably due to a higher prevalence of heart failure. The second study [39] compared treatment with FCM vs. iron gluconate and showed that FCM is more effective in restoring hemoglobin levels and improving functional capacity after cardiac surgery.…”

Pre-operative Intravenous Iron to Optimise Patients Before Cardiac Surgery

“…A retrospective study comparing ferric gluconate and ferric carboxymaltose treatment in IDA patients following cardiac surgery showed improved exercise capacity at time of discharge in the latter treatment group. There was no control group present in this study, so it is difficult to ascertain whether the improvement may have been due to correction of the underlying cardiac disease [41].…”