During cardiac rehab, patients with moderate anemia had lower initial VO2 (12.5 ml/min/kg) but showed greater median VO2 improvement (7.5 ml/min/kg) than non-anemic patients.
Does the severity of anemia affect functional capacity improvements during inpatient exercise-based cardiac rehabilitation?
Anemia is highly prevalent in patients undergoing cardiac rehabilitation, and while those with moderate anemia start with lower functional capacity, they achieve significant progress during rehabilitation.
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Abstract Background/Introduction Anemia is common after cardiac interventions and is associated with impaired functional capacity, reduced exercise tolerance, and poorer clinical outcomes. As inpatient exercise-based cardiac rehabilitation (EBCR) is widely used to restore functional performance, understanding factors influencing its effectiveness is essential. The relationship between anemia and changes in aerobic endurance during EBCR remains uncertain. Purpose This study aimed to investigate the association of change in hemoglobin levels and change in functional capacity during EBCR, as well as differences in VO₂ levels amongst different levels of anemia. Methods Patients referred for inpatient EBCR between 2022 and 2024 were analyzed in this retrospective single-center cohort study. An Hb between 10g/dl and 13g/dl (12g/dl for women) was considered as mild anemia, an Hb between 8g/dl and 10g/dl as moderate anemia. Aerobic endurance was assessed using the 6-minute walk test (6MWT) at admission and discharge. The corresponding estimated VO₂ (ml/min/kg) was calculated based on maximal power output and METs from the exercise stress test and adjusted using spiroergometry results in a subset of patients. Non-parametric ANOVA was used to assess the differences in VO₂ levels among non-anemic, mild anemic, and moderate anemic patients. Results A total of 776 patients were included in the analysis, of whom 78% were male, and who had a median age of 65 years (quartiles 57–72). The median length of stay in EBCR was 20 days (quartiles 20–27). At admission, 71.7% of patients had anemia, with 52.6% being classified as mild anemia and 19.1% as moderate anemia. The estimated VO₂ at admission was 16.7 ml/min/kg (quartiles 13.7–20.7) in the no anemia group, 15.3 ml/min/kg (quartiles 11.5–18.6) in the mild anemia group, and 12.5 ml/min/kg (quartiles 8.2–15.5) in the moderate anemia group. The levels of VO2 differed between the three different anemia groups both at admission and at discharge (Figure 1). The median VO₂ difference was 4.7 ml/min/kg (quartiles 2.6–7.2) in the no anemia group, 6.3 ml/min/kg (quartiles 3.9–8.7) in the mild anemia group, and 7.5 ml/min/kg (quartiles 5.2–10.2) in the moderate anemia group. A weak correlation was observed between hemoglobin changes from admission to discharge and VO₂ changes (ρ = 0.22, p 0.001, Figure 2). Conclusion Anemia is a common condition in EBCR and affects over two-thirds of the patients. VO2 levels differed significantly between different anemia groups. While patients with moderate anemia started with lower VO₂ levels, they achieved relevant progress during EBCR.Pairwise group comparisons Spearman's correlation
Riess et al. (Sat,) reported a other. During cardiac rehab, patients with moderate anemia had lower initial VO2 (12.5 ml/min/kg) but showed greater median VO2 improvement (7.5 ml/min/kg) than non-anemic patients.