Association between red blood cell transfusion and subsequent cardiovascular events in patients admitted to the cardiovascular intensive care unit: a single-center retrospective study.

Anemia can worsen the prognosis of patients with acute cardiovascular (CV) disease; however, the effect of red blood cell (RBC) transfusion on mid-term outcomes in such patients requiring intensive care remains unclear. Therefore, this study investigated the association between RBC transfusions during hospitalization and subsequent CV events (all-cause mortality, non-fatal myocardial infarction or stroke, admission for acute heart failure [AHF], unstable angina, and other CV events) after hospital discharge in patients admitted to the cardiovascular intensive care unit (CICU). We retrospectively enrolled 517 patients with emergent admission to the CICU for suspected acute CV disease between January and December 2018. After excluding 41 patients who died or developed CV events during hospitalization, the remaining 476 patients (44.3% with acute coronary syndrome, 22.1% with heart failure, 6.7% with acute aortic dissection, 16.0% with other cardiac diseases, and 10.9% with non-cardiac diseases) were included in the analysis and divided into transfusion (n = 111) and non-transfusion (n = 365) groups based on RBC transfusion requirements during hospitalization. All patients were followed up for subsequent CV events over a period of 180 days after hospital discharge. Compared with the non-transfusion group, the transfusion group showed a higher incidence of chronic kidney disease (73.9% vs. 48.2%, p < 0.001), Acute Physiology and Chronic Health Evaluation II score (18.0 ± 7.2 vs. 13.9 ± 5.6, p < 0.001), frequency of use of invasive mechanical support devices (52.3% vs. 13.7%, p < 0.001), and surgery rate (35.1% vs. 3.3%, p < 0.001), as well as a lower nadir hemoglobin level (8.9 ± 2.3 g/dL vs. 11.7 ± 1.9 g/dL, p < 0.001). The cumulative incidence of CV events was higher in the transfusion group than in the non-transfusion group (32.9% vs. 9.1%, log-rank p < 0.001), with a similar trend observed even after propensity score matching (29.2% vs. 12.3%, log-rank p = 0.049). RBC transfusion remained independently associated with subsequent CV events after adjusting for age, sex, nadir hemoglobin level, bleeding complications, and CV risk factors (adjusted hazard ratio, 2.46; 95% confidence interval, 1.11-5.46; p = 0.027). These findings suggest that RBC transfusion during hospitalization is independently associated with subsequent CV events in patients admitted to the CICU, indicating the need for cautious evaluation of transfusion practices based on potential long-term adverse effects.