Heart rate changes in chronically red cell transfusion-dependent patients-A dose-dependent effect of red cell transfusion: A randomized cross-over trial, interim analysis.

BACKGROUND: Restrictive red blood cell transfusion strategies are widely recommended for acute anemia but may not adequately address the needs of chronically anemic patients with transfusion-dependent myelodysplastic syndromes or myeloproliferative neoplasms. For these patients with chronic anemia, alleviating symptoms and improving quality of life are key objectives. This study evaluates the impact of additional red blood cell (RBC) transfusions administered alongside standard-of-care transfusions on heart rate, physical activity, quality of life, and cognitive function. STUDY DESIGN AND METHODS: This interim analysis of a randomized, multicenter, within-subject, cross-over trial evaluated 12 transfusion-dependent patients receiving three transfusion regimens: standard-of-care, standard-of-care + 1 additional unit, and standard-of-care + 2 additional units. The primary outcome was heart rate, and secondary outcomes were physical activity, quality of life, and cognitive performance. Heart rate and activity were continuously monitored, while questionnaires and cognitive tasks assessed outcomes at predefined visits. RESULTS: Greater hemoglobin augmentation was associated with significant reductions in heart rate, with the largest decrease in patients receiving the standard-of-care + 2 regimen. Quality of life and fatigue measures showed transient improvements with more red blood cells transfused, though these changes were not statistically significant. Cognitive performance trends suggested possible benefits, but findings were inconsistent. Physical activity, as measured by daily step count, was unaffected by transfusions. CONCLUSIONS: This interim analysis suggests that higher post-transfusion hemoglobin is associated with lower heart rate, reflecting enhanced oxygen delivery. Wearable monitoring was sensitive to these changes. Nonsignificant, hypothesis-generating trends toward improved QoL, fatigue, and cognition were observed.