Prevalence and prognostic significance of transient, persistent, and new-onset anemia after acute myocardial infarction.

Anemia is an independent indicator of mortality in patients with acute myocardial infarctions (AMIs). Although anemia may be a transient phenomenon, secondary to acute blood loss, the prevalence and clinical significance of anemia after recovery from AMI are not known. In this study, 1,065 patients with AMIs for whom postdischarge hemoglobin levels were available were assessed. Patients were categorized into 4 groups according to their anemia status at hospital discharge and at follow-up (no anemia, resolved anemia, persistent anemia, and new-onset anemia). The association between anemia and the primary end point of mortality and hospitalization for heart failure was evaluated using Cox models, using patients without anemia at the 2 time points as the reference group. At hospital discharge, anemia was present in 370 patients (34.7%). At follow-up, anemia had resolved in 162 patients (15.2%), 208 (19.5%) had persistent anemia, and 55 (5.2%) had new-onset anemia. During the follow-up period (median 27 months) 110 patients (10.3%) died, and 89 (8.4%) developed heart failure. The outcomes of patients with resolving anemia were similar to those of patients without anemia (hazard ratio 0.8, 95% confidence interval 0.5 to 1.3). In contrast, there was a marked increase in mortality and heart failure in patients with persistent (hazard ratio 1.8, 95% confidence interval 1.2 to 2.5) and new-onset (hazard ratio 1.9, 95% confidence interval 1.1 to 3.3) anemia. In conclusion, persistent or new-onset anemia occurs in a significant proportion of patients after AMI. Whereas the resolution of anemia after AMI is associated with better outcomes, persistent or new-onset anemia portends increased risk for heart failure and death.