Postoperative anemia in cardiac surgery patients: a narrative review

Early Postoperative Intravenous Iron Versus Oral Iron for the Treatment of Anemia Following Cardiac Surgery: A Randomized Controlled Trial

BACKGROUND

Postoperative anemia is a common complication after cardiac surgery, often persisting for months and substantially affecting patient recovery. Despite its prevalence, optimal treatment strategies are lacking. We aimed to evaluate whether early postoperative intravenous (IV) iron is more effective than daily oral iron in correcting anemia after cardiac surgery.

METHODS

This single-center, pragmatic randomized controlled trial enrolled 110 cardiac surgery patients with moderate postoperative anemia (hemoglobin 8-11 g/dL). Participants were randomized 1:1 to receive either a single infusion of 20 mg/kg ferric derisomaltose on postoperative day 1 (IV iron group, n = 57) or 100 mg oral ferrous sulfate twice daily for 4 weeks (oral iron group, n = 53). All outcomes were assessed at 4 weeks postrandomization. The primary composite outcome aimed to measure treatment success, defined as the proportion of participants who were (a) no longer anemic (per World Health Organization criteria) and (b) neither had received allogeneic red blood cell (RBC) transfusions after randomization. Secondary end points included differences in hemoglobin levels, RBC transfusion rates, iron metrics, 6-minute walk test distances, hospital length of stay, and patient-reported outcomes.

RESULTS

Primary outcome data were available for 53 participants in the IV iron group and 51 in the oral iron group. The proportion of participants who achieved the primary end point did not differ significantly between groups (28% vs 16%; risk difference 13%, 95% confidence interval [CI], -3% to 28%; P = .121). No statistically significant differences were observed in anemia prevalence (66% vs 82%; P = .058) or RBC transfusion rates (17% vs 33%; P = .054). Mean hemoglobin levels (± standard deviation) were higher in the IV iron group (12.0 ± 1.1 g/dL vs 11.4 ± 1.3 g/dL; P = .013). None of the participants in the IV iron group had ferritin levels <100 µg/L, compared to 26% in the oral iron group (P < .001, accounting for 95% CI for 0 numerators). No significant differences were observed in the 6-minute walk test, hospital length of stay, or patient-reported outcomes. Notably, no serious adverse events related to ferric derisomaltose were reported.

CONCLUSIONS

Early postoperative IV iron did not demonstrate superiority over oral iron for the primary outcome. However, secondary end points suggest it may improve hemoglobin levels and reduce the prevalence of postoperative iron deficiency. These findings warrant further investigation in larger trials to confirm the clinical effectiveness of early postoperative IV iron.

Design and Staged Implementation of a Multidisciplinary Preoperative Anemia Clinic at a Tertiary Care Medical Center

BACKGROUND

Preoperative anemia is common and associated with adverse outcomes in surgical patients. There is limited information to guide the design and implementation of preoperative anemia clinics (PAC), which represents a critical barrier to entry for many practices.

METHODS

This is a descriptive observational study highlighting the design and implementation of a multidisciplinary PAC, including key steps in planning, stakeholder engagement, organizational structure, identification of target populations, establishing anemia treatments, information technology and electronic health record integration, provider training, and data infrastructure. Demographic and clinical characteristics, laboratory results, and anemia treatments for individuals evaluated in the PAC from November 4, 2019 through September 15, 2023 are enumerated. Patient-reported outcomes (PROs) assessing changes in anemia symptoms and well-being after surgery are evaluated for 2 subsets of patients (one before PAC implementation [pre-PAC], another after PAC implementation [post-PAC]), without formal statistical comparison given limited sample sizes.

RESULTS

The PAC was initiated as a multidisciplinary effort under support from a Mayo Clinic Practice Transformation Award in 2019, including broad representation from anesthesiology, surgery, and medical practices, along with institutional project management support (eg, project manager, information technologists, systems engineers). While initially limited to cardiac surgery patients, the PAC underwent planned incremental expansion to include other surgical services. Over the study period, 1188 PAC consultations across 1159 unique patients met eligibility criteria, with a median age of 66 (57-73) years and 58.1% women. The most common etiology of anemia was iron deficiency (69.1%) followed by anemia related to cancer (17.3%). Anemia-directed therapies were recommended in 1038 (87.4%) encounters, with 730 (70.3%) of those receiving recommended treatment preoperatively. Seven hundred nine (97.1%) treatments included intravenous iron and 146 (20.0%) included erythropoiesis-stimulating agents. Fifteen pre-PAC and 38 post-PAC implementation patients completed PROs. PAC implementation was accompanied by earlier resolution of anemia symptoms and less pronounced declines in postoperative well-being scores.

CONCLUSIONS

This report highlights the key steps for successful PAC implementation. Treatment is possible for most patients and may be accompanied by improvements in patient-important outcomes.

Optimization of the cardiac delirium index by including age, decrease in butyrylcholinesterase actitivity, preoperative HbA1c, and postoperative hemoglobin levels: results of a secondary analysis of a prospective observational study

Introduction

Postoperative delirium (POD) after cardiac surgery significantly affects the perioperative morbidity and mortality. Butyrylcholinesterase (BChE) is an enzyme primarily produced in the liver, which plays a crucial role in the hydrolysis of acetylcholine outside of neuronal synapses, referred to as extraneuronal hydrolysis. The integration of BChE activity into the cardiac delirium (CARDEL) index might increase its predictive power for identifying POD after cardiac surgery. Therefore, the primary aim of this study was to assess the applicability of the CARDEL index and determine whether integrating the BChE activity enables optimization of the predictive model.

Methods

This secondary analysis of a prospective observational study included patients undergoing elective coronary artery bypass graft surgery. BChE activity is expressed in units per liter (U/L), while the BChE drop refers to the percentage decrease in BChE activity from pre- to postoperative levels. POD risk factors were identified using multivariate regression analysis. The predictive power of the CARDEL index and an optimized model including BChE was calculated with receiver operating characteristic (ROC) analysis.

Results

Of 93 included patients, 20 (21.5%) developed POD. Elevated preoperative HbA1c [OR 2.5 (1.2-4.8), p = 0.01], a decrease in BChE activity [%, OR 1.1 (1.0-1.2), p = 0.04], age [1 (0.94-1.1), p = 0.55], and a postoperative hemoglobin change [OR 0.86 (0.78-0.96), p < 0.001] were identified as independent risk factors for POD. While the CARDEL index showed a moderate prediction of POD [AUCROC of 0.74 (0.60-0.87)], the optimization including BChE resulted in a significant prognostic improvement: AUCROC of 0.84 (0.72-0.94, p < 0.001).

Conclusion

Despite the small size of this derivation cohort, this study identified elevated HbA1c as the strongest risk factor for the development of POD, followed by a decrease in BChE activity, postoperative anemia, and age, respectively. By including these parameters to the CARDEL index, its predictive power for the identification of POD significantly improved in this derivation cohort. Moving forward, integrating these findings into clinical practice could enhance early risk stratification and targeted intervention for patients at high risk of POD. Therefore, further research should evaluate these results in a larger, external cohort.

Efficacy of intravenous iron supplementation in reducing transfusion risk following cardiac surgery: an updated meta-analysis of randomised controlled trials

BACKGROUND

Previous meta-analyses of intravenous iron supplementation for reducing red blood cell (RBC) transfusion risk after cardiac surgery were inconclusive because of limited data. This updated meta-analysis incorporates recent evidence.

METHODS

Major databases were searched on May 2, 2024 for randomised controlled trials comparing the incidence of RBC transfusion between adult patients receiving intravenous iron supplementation and those receiving controls (i.e. oral iron or placebo) after cardiac surgery. The secondary outcomes included the number of RBC units transfused, postoperative haemoglobin levels, iron status, complications, and length of hospital stay. Trial sequential analysis was conducted to examine the robustness of evidence.

RESULTS

Fourteen randomised controlled trials including 2043 subjects were identified. Intravenous iron supplementation was found to reduce the RBC transfusion risk compared with controls (relative risk 0.77, 95% confidence interval [CI] 0.65-0.91, P=0.002, n=1955, I2=61%, certainty of evidence: moderate). The trial sequential analysis supported the robustness of the evidence. Furthermore, haemoglobin levels were higher in the intravenous iron supplementation group on postoperative days 4-10 (mean difference 0.17 g dl-1, 95% CI 0.06-0.29, n=1989) and >21 days (mean difference 0.66 g/dl-1, 95% CI 0.36-0.95, n=1008). Postoperative iron status also improved with Intravenous iron supplementation, particularly on postoperative days 4-10. There were no significant differences in other outcomes, including mortality.

CONCLUSIONS

Intravenous iron supplementation can reduce RBC transfusion risk and improve postoperative haemoglobin level and iron status after cardiac surgery, supporting the implementation of Intravenous iron supplementation in perioperative blood management strategies.

SYSTEMATIC REVIEW PROTOCOL

CRD42024542206 (PROSPERO).