Hospital-Acquired Anemia in Patients with Acute Coronary Syndrome: Epidemiology and Potential Impact on Long-Term Outcome

Background: Anemia (either pre-existing or hospital-acquired) is considered an independent predictor of mortality in acute coronary syndromes. However, it is still not clear whether anemia should be considered as a marker of worse health status or a therapeutic target. We sought to investigate the relationship between hospital-acquired anemia and clinical and laboratory findings and to assess the association with mortality and major cardiovascular events at long-term follow-up. Methods: Patients consecutively admitted at Niguarda Hospital between February 2014 and November 2020 for an acute coronary syndrome were included in this cohort analysis and classified as anemic at admission (group A), with normal hemoglobin at admission but developing anemia during hospitalization (hospital-acquired anemia) (group B); and with normal hemoglobin levels throughout admission (group C). Results: Among 1294 patients included, group A included 353 (27%) patients, group B 468 (36%), and group C 473 patients (37%). In terms of cardiovascular burden and incidence of death, major cardiovascular events and bleeding at 4.9-year median follow-up, group B had an intermediate risk profile as compared with A and C. Baseline anemia was an independent predictor of death (hazard ratio 1.51; 95% confidence interval, 1.02-2.25; P = .04) along with frailty, Charlson comorbidity Index, estimated glomerular filtration rate, previous myocardial infarction, and left ventricular ejection fraction. Conversely, hospital-acquired anemia was not associated with increased mortality (hazard ratio 1.18; 95% confidence interval, 0.8-1.75; P = .4). Conclusions: Hospital-acquired anemia affects one-third of patients hospitalized for acute coronary syndrome and is associated with age, frailty, and comorbidity burden, but was not found to be an independent predictor of long-term mortality.